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Taken broadly as
the progressive improvement of man's understanding of nature, the intellectual
enterprise of science originally formed an integral part of philosophy, and the
two areas of inquiry have never finally separated. Little more than a hundred
years ago, theoretical physics--concerned with the fundamental debate about
physical nature--was still described as "natural philosophy," as
distinguished from the two other chief divisions of abstract discussion, viz.,
moral philosophy and metaphysical philosophy--the latter including ontology, the
study of the deepest nature of reality or being. In fact, only during the 20th
century, following the professionalization and specialization of the natural
sciences, did the philosophy of science
become recognized as a separate discipline. (see also nature,
philosophy of) |
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Methodological and
epistemological issues--i.e., issues regarding the investigator's manner
of approach to nature--are treated in this section. Issues regarding the
substantive character of nature as so revealed--i.e., as it is in and of
itself--are treated below in Philosophy
of nature . |
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The philosophy of
science attempts first to elucidate the elements involved in scientific
inquiry--observational procedures, patterns of argument, methods of
representation and calculation, metaphysical presuppositions--and then to
evaluate the grounds of their validity from the points of view of formal logic,
practical methodology, and metaphysics. The philosophy of science is thus a
topic for explicit analysis just as are other subdivisions of philosophy. The
boundaries between these subdivisions are, at certain points, somewhat
arbitrary; it is not easy to separate completely, for example, the philosophical
validation of scientific hypotheses from the formal study of inductive logic
(which reasons from facts to general principles), or the debate about
observation in philosophy of science from that in epistemology (the theory of
knowledge). (see also induction)
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Historically, the
preoccupations of those who, if living today, would be called philosophers of
science have been of two main kinds--ontological and epistemological, or
epistemic. This division reflects a long-standing distinction between object and
subject--i.e., between nature, regarded as that about which man sets out
to acquire scientific knowledge, and man himself, regarded as the creator and
either discoverer or possessor of that knowledge. Since 1920, new directions
within physics, particularly in quantum mechanics, have discredited any
hard-and-fast distinction between the knower and the known or between the
observer and his observation. Nevertheless, the distinction remains relevant on
an everyday level and can be cautiously retained for the purposes of initial
exposition. |
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The ontological
preoccupations of philosophers of science frequently overlap into the
substantive areas of the sciences themselves, for they explore the general
problem, (see also ontology)
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What
kinds of entities and elements or theoretical terms can properly figure in man's
scientific theories? And what sort of existence, or other objective status, do
such things possess?
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In particular
cases, this general problem has inevitably raised questions of substance as well
as of intellectual method. An early 20th-century debate between two Austrian
physicists, Ernst Mach and Ludwig
Boltzmann, and a German physical chemist, Wilhelm
Ostwald, about the existence and reality of atoms, for instance,
involved both substantive issues of physics and chemistry and philosophical
issues of a more strictly analytical kind. |
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Until recently the
epistemic concerns of the subject have been more purely philosophical, though
this autonomy is now being challenged by studies in psychology that explore
cognitive processes and others in sociology that examine the conditioning of
cognition through interpersonal and group relationships. Epistemologically,
philosophers of science have analyzed and evaluated the concepts and methods
employed in studying natural phenomena and human behaviour, whether individual
or collective; this analysis has covered the general concepts and methods
characteristic of all scientific inquiries and also the more particular ones
that distinguish the subject matters and problems of different special sciences.
In treating the epistemic issues that arise about science and scientific
procedures, the emphasis in this article is placed upon their consideration in
general terms; the concepts and methods peculiar to a discipline, say,
sociology, are discussed elsewhere. |
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With its vast range
of concerns, the philosophy of science has attracted the attention of men with
very different professional backgrounds and interests. At one extreme, as in the
writings of Ernest Haeckel,
the German Darwinian evolutionist, it has merged into a sweeping kind of popular
science; at an opposite extreme, as in 20th-century Logical
Positivism or Logical Empiricism (see below The
20th-century debate: Positivists versus historians
), which holds that knowledge is only what is scientifically
verifiable, it has been treated as an extension of formal logic and conceptual
analysis. Between these extremes, as in the work of the British astrophysicist Arthur
Eddington and the German quantum physicist Werner
Heisenberg, the philosophy of science has moved to the frontiers of
the sciences and has directly confronted problems about the existence, status,
and validity of theoretical entities and concepts. (see also positivism)
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Correspondingly,
the philosophy of science has been approached in very diverse spirits, ranging
from the highly abstract and mathematical to the concrete and historical and
from the severely positivistic to the frankly theological. From Ren?Descartes in
the 17th century to the Logical Positivist Otto Neurath in the 20th, the success
of pure mathematics and logic has inspired the mathematically minded to cast the
whole of natural science into a single formal system after the pattern of
geometry. Their opponents--from John Locke, an 18th-century British Empiricist,
to N.R. Hanson, a recent U.S. philosopher of science--have sought the proper
basis of man's intellectual confidence in the nature of scientific
investigation, regarded as a human activity. Equally, Positivists such as Hans
Reichenbach, a 20th-century German-American philosopher, have looked
to philosophy for proof that scientific inquiries alone can provide knowledge
worthy of the name; while theists such as Pierre
Duhem, a French theoretical physicist, have argued that the claims of
science are inherently limited and so leave room for other, more embracing
varieties of metaphysical and religious truth. |
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This diversity of
concerns and approaches within the philosophy of science has affected its
relation with other neighbouring disciplines. On a practical plane, for
instance, different philosophical interpretations have implied different
procedures for testing and assessing the strength of rival concepts and
hypotheses. Thus, no clear dividing line can be drawn between the philosophical
analysis of scientific theories and the statistical analysis of scientific
procedures and experiments or, notably, between the philosophy of science and
the history of scientific ideas. Recent debates indicate that the particular
questions that a historian of science brings to his analysis of scientific
change inescapably depend on his philosophical attitudes and commitments. (see
also Index: science, history of)
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On a more general
and abstract level, the philosophy of science has never been definitively
separated from metaphysics and epistemology. Indeed, some 20th-century
philosophers--for instance, the U.S. philosophical logician Willard V. Quine--effectively restrict the legitimate areas of
metaphysics and epistemology to what have here been called the ontal and
epistemic aspects of the philosophy of science. In Quine's view, the traditional
ontological problem of what there is in the world as man knows it must be
attacked by a logical analysis of the claims about what kinds of things exist
that are implicit in alternative theoretical systems. Meanwhile, the work of
such cognitive psychologists as Switzerland's Jean
Piaget, who explored the processes involved in the genesis of
knowledge, is eroding the barriers between the logical analysis of conceptual
systems, the psychological investigation of thought
processes, and the epistemological validation of intellectual procedures.
Piaget, for instance, based his investigations into the acquisition of concepts
on a philosophy akin to that of Kant, who held that all knowledge bears the
imprint of the mind's own structure; and, though a psychologist himself, Piaget
referred to certain aspects of his work as "genetic epistemology," a
philosophical designation. |
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The present survey
of the philosophy of science, therefore, contains no effort to prejudge the
central question, whether the methods of logical analysis alone are legitimate
or whether at certain points the subject legitimately overlaps into such
neighbouring subjects as cognitive psychology, the history of science, and
epistemology. Philosophers of science themselves have been sharply divided, some
rejecting any alliance except with logic, others cultivating its wider
historical and behavioral connections; and both points of view must thus be
taken into account. |
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2.1.2.1
Classical and medieval periods: the beginnings of a philosophy of nature.
At the outset the
problems of science were as much those of method as of substance and were
inseparable from those of what has long been called natural
philosophy. The first attempts to move beyond traditional mythologies
to a rational account of nature, beginning with the Ionian and south Italian
philosophers around 600 BC, involved the sorts of elements that any such account
should comprise. Detailed empirical, or observational, considerations favouring
one or another of the rival accounts were premature. Were, for example, the
diverse phenomena of nature manifestations of one single enduring form of matter
or of several elementary substances mixed together, and was the fundamental
substance continuous and fluid-like, or discrete and atomic? Others asked
whether the observed forms of phenomena were evidence, rather, of some
universal, underlying mind or of a variety of coexisting kinds of spirit
responsible for phenomena having different orders of complexity. (see also Ionian
school) |
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The Pre-Socratics
based their answers at least as much on epistemic grounds--i.e., on what
type of account would be genuinely intelligible--as on ontal or empirical ones--i.e.,
on what sorts of enduring entities could possibly have, or be found in
experience to have, the required kind of existence. Their answers ranged from
the ontal Realism of Parmenides,
foremost philosopher of Eleaticism--a
school of southern Italy according to which all changes are transitory
appearances concealing the mutual relations of deeper, unchanging realities--to
the critical skepticism of Heracleitus--the
Ephesian philosopher according to whom nothing in nature as man knows it can
ever have this Parmenidean reality, and everything empirical is in flux. |
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Though Plato
and Aristotle displayed more
precise concern for actual cases, their philosophies of science still rested on
the same mixture of ontological, epistemological, and empirical considerations.
Questions about nature discussed in Plato's Timaeus and Aristotle's Physics,
for instance, were neither purely metaphysical nor purely empirical in
character though they had a methodological aspect akin to that of modern
philosophy of science. Moreover, Plato's construction of the fundamental
theories of science around concepts and patterns borrowed from geometry have had
a profound influence in the modern period--upon Ren?Descartes,
for example, in the 17th century and upon the founder of modern logic, the
German mathematician Gottlob Frege,
in the 1880s and after. |
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Mathematical
entities alone, Plato argued, have the sort of enduring intelligibility that
Parmenides had rightly demanded of the ultimate constituents in a rational
science of nature. Thus, only a physical theory built on a numerical and
geometrical framework will reveal the truly permanent structures and
relationships behind the evident flux of phenomena. Within such a theory, all
inferences will be self-evidently valid at all times and so exempt from the
mutability of empirical events; correspondingly, the numbers and figures of
formal mathematics will have an immutability denied to familiar physical
objects. Planetary astronomy
and the theory of matter were, in Plato's view, scientific fields within which
this mathematical methodology showed immediate promise; the movements of the
planets must be explained by constructions drawn from three-dimensional
geometry, and the physics of matter seemingly involved atoms with shapes
reflecting the geometry of the five regular solids (the tetrahedron,
dodecahedron, etc.). In either case the mathematical theories themselves would
alone be fully exact and intelligible, whereas empirical objects and processes
could be no more than transitory and approximate illustrations of the enduring
entities and theoretical relations underlying them. |
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Given that
Aristotle's scientific preoccupations were centred on marine biology rather than
planetary movements, he naturally developed a very different scientific
methodology. In his view, mathematical entities and relations were too
completely general and too remote from actual experience to explain the
qualitative details of empirical entities. So the ultimate elements of nature
must be not Plato's abstract mathematical forms that supposedly existed apart
from actual phenomena but rather certain more specific entities, recognizable
within the familiar sequences of empirical experience. Instances of such basic
essences could be discovered in the typical life cycles of different creatures;
for example, the morphogenesis
of a seed exemplifies the "coming into being" of the corresponding
type of animal or plant, of which the mature specific form--as defined by its
essence--is the natural destination of its development. Having recognized the
natural destinations toward which natural processes of different kinds were
directed, it was then possible to construct a comprehensive classification of
essences in terms of which the whole natural world would, in principle, be
intelligible. Explanations within such an all-embracing natural history might
not be self-evidently general and immutable, as were those of Plato's geometry,
but the theoretical inferences involved would be no less deductive or necessary.
It would also account directly for the specific qualitative characters of
different observed objects and processes. (see also taxonomy)
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The themes stated
by Plato and Aristotle are still represented today by two rival approaches to
the philosophy of science--one (Platonic) based in logic, the other
(Aristotelian) based in the history of science. Between them they dominated the
subject during the later period of Greek antiquity, otherwise notable only for
the debate between the Atomist successors of Democritus and Epicurus
and the Stoic philosophers, led by Zeno of Citium. This debate provided the
first profound analysis of the strengths and weaknesses of atomistic
explanation. Epicureans argued for a purely corpuscular view in which the
individual units of matter moved quite independently, except when they were in
actual contact. For the Stoics the empirical world was intelligible only in
terms of interactions and stable patterns maintained by harmonies operative at a
distance. (see also atomism,
Stoicism, corpuscle)
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These two
debates--between Platonists and Aristotelians and between Stoics and
Epicureans--presented clearly and for the first time the chief alternative modes
of explanation available to science and analyzed their possibilities and
limitations in general terms. More than 2,000 years before the rise of modern
thermodynamics and field theory, for instance, Aristotle had already recognized
the difficulties of explaining changes in physical state (e.g., melting
and evaporation) within a purely atomistic theory of matter. Even earlier, Plato
had demonstrated the possibility of a unified mathematical explanation of the
differences between different kinds of material substance. In the 20th century
the theoretical physicist Werner Heisenberg cited pre-Socratic arguments
regarding the ultimate constitution of nature as relevant to contemporary
problems. |
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By contrast with
the period before Euclid the geometer (i.e., to 300 BC), the ensuing
Hellenistic, Islamic, and medieval periods added little to the
understanding of scientific methodology and explanation. From the Alexandrian
astronomer Ptolemy, who
detailed the geocentric theory, most natural philosophers deliberately
restricted their intellectual claims in an instrumentalist manner--i.e., by
endeavouring merely to "save the phenomena" by devising successful
mathematical procedures for predicting, for example, lunar eclipses and
planetary motions. In this way they disregarded the mechanisms responsible for
those phenomena, thus preserving the computational techniques of the sciences
from the risk of conflict with theology for the following 1,250 years, until the
time of Copernicus. |
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In the High Middle
Ages, accordingly, the possibility that man could make himself the intellectual
master of nature was largely neglected. Human understanding was dependent on
God's illumination. The reliability of scientific knowledge lay not in the
merits of its methodology but in the divine grace. Hence, man had no direct line
of access to nature; the only road to knowledge was through the divine mind.
Thus, all the central questions in the philosophy of science were restated as
theological questions about the relationship between God's omniscience and the
more limited knowledge of man. In this context the metaphor of
"illumination" was taken so seriously in the 13th century that the
subject of optics was cultivated by a distinguished Oxford scholar as much for
its theological implications as for its physical content. (see also theology)
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Although the
intellectual Renaissance of the 16th and 17th centuries was accompanied by a
secularization of learning, which shifted the centre of philosophical and
scientific debate from monasteries to universities--and even to salons--the link
between philosophy and theology was not abruptly snapped. Descartes, Newton, and
Leibniz, the leading scholars of the time, were concerned to demonstrate that
their positions were compatible with sound theology. Medieval controversies
about human knowledge and divine grace found an echo in such arguments as
Descartes's assertion that the rational methods of inquiry can be relied on only
provided that God does not deliberately deceive us. Two new factors, however,
combined to give the 17th-century debate about scientific methodology a new
autonomy. First, philosophy now posed the central questions in the philosophy of
science--both about the origins and functions of scientific concepts and about
the structure and validity of scientific arguments--and faced them directly,
instead of only as refracted through a theological prism. Second, these
questions were acquiring an immediate relevance and significance, simply because
men were then launching new, empirically based theories of nature with a
seriousness unknown for some 1,200 years. |
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Between 1600 and
1800 the debate in the philosophy of science was barely separable from that
within science itself. From Bacon and Galileo by way of Descartes and Leibniz to
Laplace and Kant, the major participants in the philosophical debate played
significant roles on the scientific stage as well. Thus, Bacon,
author of the method of exhaustive induction (see the paragraphs below), and
Descartes both attempted to formulate explicitly a new method for the
improvement of the intellect--i.e., codifying the rational procedures of
science in a way that would free them from arbitrary and unfounded or
superstitious assumptions (Bacon's idols) and ground them in a logically
impregnable manner on the properties of "clear and distinct," or
self-evidently valid, concepts (as distinguished by Descartes). (see also rationalism)
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To be sure, the two
men offered different recipes for a rational science and described the outcome
of a properly conducted scientific inquiry in quite different terms. On the one
hand, Bacon was preoccupied with empirically observed facts as the starting
point for all science and relied on theories only insofar as they were derived
from those facts. Ideally, he held that the scientist should provide an
exhaustive enumeration of all examples of the empirical phenomenon under
investigation as a preliminary to identifying the natural "form" of
which they were the manifestation. Though Bacon remained unclear about the exact
character of the abstraction involved, he is commonly assumed to have claimed
that theoretical propositions in science are justified only if they have been
deduced formally from such an enumeration. (see also scientific
method, Empiricism)
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In contrast to such
so-called "Baconian induction," Descartes focussed upon the problem of
constructing self-consistent and coherent deductive systems of theory, within
which argument would proceed with the formal security familiar in Euclidean
geometry. Whereas Bacon had reacted against the Scholastic reliance on
Aristotle's authority by calling for a return to firsthand experience, Descartes
reacted against the Skepticism
of 16th-century humanists by pointing to mathematics as the pattern to which all
genuinely certain knowledge about nature could aspire. Inasmuch as Euclid's
axioms, definitions, and postulates had captured the intrinsic characteristics
of spatial relations and provided a theoretical starting point from which the
whole of geometry could be deductively inferred, the task for 17th-century
physics was to extend Euclid's intellectual structure by adding further, equally
self-evident axioms, definitions, and postulates. Only in this way could the
theories of motion, magnetism, and heat--eventually those of physiology and
cosmology, too--achieve the same necessary deductive authority. Descartes set
out to show, in the four volumes of his Principia
Philosophiae ("Principles of Philosophy"), how
all of the familiar phenomena of physics could be accounted for by a single,
fully comprehensive system of mathematical theory, based on Euclidean
foundations and conforming to his own deductivist principles. The very
possibility of so interpreting nature was so impressive to Descartes that it
lent a "moral certainty" to his conclusions. (see also scientific
theory, scholasticism)
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The arguments of
Bacon and Descartes were really manifestos; both offered intellectual programs
for a natural science yet to be built, and, while it is true that during the
next 150 years, Galileo, Newton, and many others actually constructed the new
physical science for which the philosophers had been calling, it is also true
that the form of the resulting theories was, nonetheless, not exactly what
either man had foreseen. On the one hand, there was little Baconian induction in
Newton's intellectual procedures. Those 17th-century scientists, such as Robert
Boyle--one of the founders of modern chemistry--who seriously
attempted to apply Bacon's maxims found his pedestrian advice to be more of a
hindrance than a help in the formulation of illuminating theoretical concepts.
(It was said, somewhat unkindly, that Bacon "philosophized like a Lord
Chancellor.") On the other hand, though Newton
was powerfully influenced by Descartes's mathematical example, he followed his
methodological maxims only up to a point. Granted that the theory of motion and
gravitation of Newton's Principia did indeed conform to Descartes's
recipe--adding further dynamical axioms, definitions, and postulates to those of
Euclid's geometry--Newton nonetheless made no pretense of proving, in advance of
empirical evidence, that these additional assumptions were uniquely self-evident
and valid. Instead, he treated them as working assumptions to be accepted
hypothetically for just so long as their consequences threw light, in exact
detail, on hitherto-unexplained phenomena. Inevitably, the epistemic claims to
be made on behalf of such explanations fell short of Descartes's full
"deductivist" ambitions. Newton knew of no phenomena, for instance,
that evinced the mechanisms of gravitational attraction and saw no point in
"feigning hypotheses" about them. |
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In this way, Newton
devised in practice--almost inadvertently--what philosophers of science have
since labelled the hypothetico-deductive
method, in which, as theorized by Descartes, the proper form of a
theory is seen as a mathematical system in which particular empirical phenomena
are explained by relating them back deductively to a small number of general
principles and definitions. The method, however, abandons the Cartesian claim
that those principles and definitions can themselves be established, finally and
conclusively, before inquiring what light their consequences throw on actual
scientific problems and phenomena. |
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From 1700 on, the
terrain of debate in the philosophy of science shifted. At first, attacks on
Newton's methods and assumptions by Leibniz, Berkeley, and the remaining
Cartesians continued, from different points of view. But by 1740 the time for
both manifestos and objections was past; the basic scientific soundness of
Newton's concepts was no longer in doubt, and the philosophical question thus
became retrospective, viz., How had Newton done it? Over this new question,
18th-century philosophers were divided into three camps: Empiricism,
Rationalism, and Kantianism.
There were those who believed, like the Scottish Skeptic David Hume, that
Newton's philosophy conformed to the Empiricist maxims of Francis Bacon and John
Locke. Again, there were those--like the Swiss mathematician Leonhard Euler, one
of the founders of modern analysis, and Immanuel
Kant in his younger days--who assumed that Newton's physical
principles would eventually be put on a fully demonstrative or self-evident
basis as required by Cartesian Rationalism. Neither of these positions proved
entirely successful, as Kant himself came to recognize: the Empiricists failed
to do justice to the deductive rigour of Newton's theoretical arguments; and the
Rationalists could not rigorously demonstrate the mathematical uniqueness of
Newton's system. As was already known, even Euclidean geometry, which involves
the axiom of parallels (according to which one, and only one, line can be drawn
through a given point parallel to another line) could no longer claim a formal
uniqueness. It had been shown, in 1733 and again in 1766, that alternative
geometrical systems can consistently be developed in which the axiom of
parallels is replaced by other mathematically acceptable alternatives. Clearly,
the authority claimed for Newton's concepts and methodology could no longer be
sustained in the old Rationalist way; thus a third alternative, that of
Kantianism, arose. |
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One of the prime
goals of Kant's so-called critical philosophy, with its famous so-called transcendental
method, in which knowledge reflects the categorial structure of the
mind, was to provide an alternative philosophical justification of Newton's
results. The system of concepts used in Euclidean geometry and Newtonian physics
is uniquely relevant to man's actual experience, Kant argued, not because the
empirical applicability of their principles is self-evident--no such
self-evidence can tell the inquirer anything about external nature. Still less
is it because their inductive support is so strong--no Baconian argument can
yield the required kind of certainty. Rather, it is because the scientist can
arrive at a coherent, rational system of empirically applicable explanations
only by constructing his theories around just those (Euclidean and Newtonian)
concepts. He could, in fact, go even further. Euclidean axioms are required,
Kant claimed, not merely for science alone; they specify explicitly cognitive
structures (of the mind) that are implicitly involved also--as so-called forms
of intuition (specifically of space and time)--in the prescientific rational
organization of sensory experience into a coherent, intelligible world of
substantial objects seen as interacting by causal processes. A grasp of Kant's
transcendental method would then enable a thinker to recognize (or so Kant
hoped) how and in what respects the use of his established system of rational
forms and categories is indispensable alike for any coherent understanding or
even for any experience. (see also Euclidean
geometry) |
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Kant's ambitious
philosophical enterprise took a long time to digest. A century later, in the
1880s, philosophers of science as different in other ways as the Austrian
phenomenalist Ernst Mach and Heinrich
Hertz, pioneer in electromagnetic wave theory, were both pursuing
questions opened up by Kant; and some of their implications were still being
explored in the 1970s, as, for example, in cognitive psychology. In general
terms, Kant's central thesis--i.e., that man confers a structure on his
knowledge through the concepts and categories that he brings to the formation
and interpretation of experience--has proved extremely fertile: it has helped in
the analysis of theory construction, and it has suggested in sensory psychology
that man's very capacity for perception
can yield effective knowledge only to the extent that his sensory inputs
themselves have a cognitive or conceptual structure. |
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In one respect, to
be sure, Kant seems in retrospect to have attempted too much. Including in man's
framework of sensory and intellectual organization all of Euclidean geometry and
of fundamental Newtonian physics and the prescientific notions of substance and
cause, Kant set out to demonstrate a priori that man's actual current framework
is the one and only effective framework--a proof which, as is known today, was
misguided, for its thesis is simply not the case. This is so, not merely because
alternative systems of geometry and dynamics can be developed consistently in
mathematical terms (for Kant himself was aware of that fact); rather, it is so
because 20th-century astrophysics and quantum mechanics have succeeded in giving
non-Euclidean and
post-Newtonian concepts an entirely coherent empirical application in the
scientific explanation of natural phenomena--and this was something that Kant
was not prepared to contemplate. Pure mathematics aside, indeed, Kant and most
of his immediate successors were convinced that Euclid and Newton between them
had somehow hit on a uniquely adequate system of geometry and physics--if
not on the final mathematical truth about nature. |
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For about 100
years, then, the epistemic foundations and ontal commitments of this so-called
classical science were largely taken for granted. The 19th-century debate in
philosophy of science, accordingly, concentrated on peripheral topics and
skirted all issues that might have called into question the ascendency of Euclid
and Newton. The validity of the classical system having been assumed, the
questions remaining for debate involved only its interpretation and
implications; and the resulting positions can be classified, with slight
oversimplification, under the headings of mechanistic (or Materialist) and
Idealist doctrines, respectively. |
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The Idealists took
to heart Kant's thesis that the cognitive structure of experience is imposed
upon nature rather than discovered in it and sought to explore its broader
consequences. The psychology of sensory perception, for example, previously
barred from direct scientific study by Descartes's absolute separation of mind
from matter, was now opened up for exploration; thus, by the mid-19th century, Hermann
von Helmholtz, pioneer in a broad range of scientific studies,
embarked on the remarkable investigations into the production of man's sensory
experiences or ideas set out in his monumental Handbuch der physiologischen
Optik (1856-67; Eng. trans., Physiological Optics, 1921-25). (see
also idealism) |
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For most of Kant's
successors, however, the Idealist road led away from philosophy of science into
other areas--particularly, into political ideology, philosophy of history, and
sociology. Thus, it was not until well into the 20th century that the
distinguished joint relativity-quantum theorist Sir
Arthur Eddington, in his Fundamental Theory (1946), once again
took up seriously the basic task of Kantian Idealism, viz., that of
demonstrating, on a priori epistemological principles, that man's physical
interpretation of nature embodies certain necessary structures imposed on
physics by the character of his theoretical procedures themselves. |
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Meanwhile, the
19th-century mechanistic Materialists
were disregarding Kant's central insights and concentrating instead on the
apparent implications of the Newtonian system for other branches of science. A
vigorous philosophical debate resulted, particularly in those fields that were
just developing effective explanatory methods and theoretical concepts of their
own. One good example of such a field was physiology, in which the work of a pioneering experimental
physiologist, Claude Bernard,
with its striking theoretical analysis of the vasomotor system and other
regulatory mechanisms in the body, which anticipated 20th-century ideas about
feedback systems, finally broke a long-standing deadlock between two opposed
groups of scientists--the extreme mechanists, who recognized no difference at
all between organic or physiological processes and the physicochemical phenomena
of the inorganic world, and the outright vitalists, who insisted that the two
kinds of phenomena were absolutely different. The debate also encouraged an
epiphenomenal view of experience--as a kind of subjective mental froth without
causal influence on the underlying physical mechanisms--and so sharpened the
apparent threat to all claims about human "free will." Today it seems,
indeed, that the sweeping conclusions of such scientific popularizers as the
German evolutionist Ernst Haeckel,
who wedded the ideas of classical physics with the new Darwinian history of
nature to form a comprehensive Materialistic cosmology, or
"anti-theology," carried more weight at the time than they seem in
retrospect to have deserved. (see also vitalism)
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There was one
promising exchange about the central epistemic issues in the philosophy of
science in mid-century, that which took place between William
Whewell, a British philosopher and historian of science noted for his
work on the theory of induction, and the political essayist, John Stuart Mill;
but this was abortive. The debate ended in cross-purposes, largely on account of
differences in temperament and preoccupations. Whewell's knowledge--not merely
of contemporary physical science but of its whole historical background--was
both broad and detailed. The mathematical necessity of arguments such as those
in Newtonian dynamics impressed him quite as much as it had impressed Kant; but
he gave a less grandiose account of the reasons for this necessity. Whewell's
philosophy, a Kantian variation on Newton's hypothetico-deductive method, was
historicized: it was only by a progressive approach that physicists arrived at
the most coherent and comprehensive systems of what Whewell called
"consilient" hypotheses--or separately derived, yet concordant, sets
of laws--that were compatible with the empirical knowledge then at their
disposal. Mill, on the other
hand, principally concerned with the methodology of the social sciences,
concentrated on the observational basis of science to the neglect of its
theoretical organization and so emphasized the contingent, or unnecessitated,
nature of all genuine empirical knowledge. In due course, certain of his
doctrines, such as his account of arithmetical formulas as being a variety of
empirical generalization, exposed him to some ridicule; but, for the time being,
while the sheer bulk and learning of Whewell's writings muffled the force of his
arguments, Mill's more fluent and less technical style of exposition captured
the popular attention. |
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In consequence, it
was not until the 1890s and early 1900s that serious doubts grew up about the
finality of the Newtonian synthesis; and the writings of Ernst Mach, Heinrich
Hertz, the eminent German physicist Max Planck, Pierre Duhem, and others
inaugurated the new phase of far-reaching critical reanalysis characteristic of
20th-century philosophy of science. In one way or another, all of these men
stood back and looked at the Euclidean and Newtonian systems with fresh and less
committed eyes. They had learned Kant's lesson about the constructive character
of formal theories, without sharing his belief in the unique rationality of the
classical synthesis; and, as a result, the central topics of their discussions
turned on the best ways of restating the Kantian problem. Granting that the
intellectual activity of theory construction has the effect of building a
physical necessity into man's theoretical arguments, they asked, what then
follows, ontologically, about the reality or conventionality of the resulting
atoms, forces, electrons, etc., and what can be said, epistemologically, about
the cognitive status and logical validity of its theoretical principles? |
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At one extreme, an
Austrian physicist and philosopher Ernst Mach, and Richard
Avenarius, the author of a philosophy known as empiriocriticism,
expounded a sensationalist form of Empiricism reminiscent of David Hume, who had
insisted that all ideas be traceable to "impressions" (sensations). On
their view, theoretical concepts are intellectual fictions, introduced to
achieve economy in the intellectual organization of sensory impressions, or
observations, for which alone ontal primacy can be claimed. Correspondingly, all
claims to scientific knowledge had epistemic validity for them only insofar as
they could be grounded in such sense impressions. As against this
instrumentalist or reductionist position, Max
Planck, author of the quantum theory, defended a qualified Realism,
which, at the least, expressed the ideal toward which all conceptual development
in physics proceeds; for, without a belief in the enduring reality of external
nature, he argued, all motive for theoretical improvement in science would
vanish. Between these two extremes, Henri
Poincar?, equally distinguished in mathematics and the philosophy of
science, and Pierre Duhem, a French theoretical physicist, occupied a range of
intermediate so-called conventionalist
positions, which attempted to do justice to the arbitrary elements in theory
construction while avoiding the sort of radical doubt about the ontal status of
theoretical entities that led Mach into lifelong Skepticism about the reality of
atoms. |
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In the mid-20th
century, debate in the philosophy of science became notably detailed, elaborate,
and critical; those 50 years, in fact, have seen the subject finally achieving
the status of a well-established professional discipline. Not least among the
causes of this development have been the profound changes that have taken place
since 1900 within theoretical physics and other fundamental branches of natural
science. So long as the classical synthesis of Euclid and Newton retained its
unquestioned authority, there had been little occasion to probe its ontological
and epistemological bases at all deeply; but relativity
theory--which qualified earlier geometries and laws in terms of new insights
into the tie-ins between space and time--and quantum
mechanics--which qualified them in terms of a statistical and
indeterministic formulation--posed a frontal challenge to that synthesis and
inevitably provoked critical and philosophical questions about the validity of
the methods and assumptions on which it had relied. Consequently, between 1920
and 1940 there arose a renewed interaction between theoretical physicists and
philosophers of science--especially between the Viennese Positivists and the
authors of the new quantum mechanics. |
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The main themes of
the subsequent debate were largely those introduced into discussion in the
period around 1900. Mach's critical reductionism,
based on his Beitr?e zur Analyse der Empfindungen (1886; Eng. trans., Contributions
to the Analysis of the Sensations, 1897), in which he
tried to reduce all knowledge to statements about sensations, was a prime source
both of the Positivism and Logical Empiricism of the Vienna
Circle--a group of eminent philosophers and scientists that met
regularly in Vienna during the 1920s and 1930s--and also of the epistemological
theories about sense-data and logical constructions developed in Britain about
the same time by Bertrand Russell,
perhaps the foremost logician and philosopher then in England; by G.E.
Moore, a meticulous pioneer in Linguistic Analysis; and by others.
Meanwhile, the qualified Realism of Planck and Hertz was carried further by such
men as Norman Campbell, an English physicist known for his
sharpening of the distinction between laws and theories, and Karl
Popper, an Austro-English philosopher recognized for his theory of
falsifiability, both of whose views reflect the explicit methodology of many
working scientists today. A notable exception would be the Positivistic
followers of Niels Bohr in
the Copenhagen school of theoretical physics. Finally, there has continued to be
substantial support for intermediate, conventionalist compromises, with Kantian
overtones, along the general lines developed by Poincar?and Duhem.
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From the rich
complexity of recent philosophy of science, two main strands may be selected for
special mention here. The first is the strand of neo-Humean Positivism,
which first developed in the Vienna Circle and has flourished more recently in
the United States and has been fundamentally preoccupied with epistemological
issues. While largely abandoning Mach's belief that sensations are the sole
ultimate ground of knowledge, its proponents have continued, with Mach, to
regard theoretical entities as fictions or logical constructs, the validity of
which depends entirely on the capacity to give them a basis in empirical
observations. This neo-Humean position has derived much encouragement, if not
formal confirmation, both from Einstein's
emphasis on the essential role of the observer in relativity physics and from
the attack from the side of quantum theory made by the German physicist Werner
Heisenberg on any sharp distinction, at the subatomic level, between
the observer, his observation, and the system observed (see below Philosophy
of nature ). |
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The Logical
Positivists and Empiricists harnessed to these epistemic arguments a formal
apparatus taken over from the philosophy of mathematics--specifically, from
Russell and Whitehead's Principia
Mathematica (1910-13). In their view, the activity of
theory construction is logically equivalent to the creation of propositional
systems, in which groups of propositions are ideally set out in axiomatic form.
So interpreted, the hypothetico-deductive
method becomes a recipe for devising a succession of progressively
more comprehensive axiom systems, based on alternative sets of general
postulates (or primitive propositions) posited without proof, from which
particular, empirical propositions can be inferred. As in the case of the
special theory of relativity, these particular propositions--for instance, that
the axis of Mercury's orbital ellipse will precess (or turn) at a certain
rate--can then be used to validate the general postulates by comparing them with
actual experience thus--directly or indirectly--substantiating the more general
primitive propositions as well. The subsequent debate within the Viennese school
has been concerned, very largely, with the exact character and force of this
substantiation--whether it be verification, confirmation, or corroboration
and/or falsification. At its most ambitious extreme, the Viennese school aimed
at constructing a single system of unified science, by which the entire corpus
of positive knowledge would be embraced in a single, all-embracing axiom system
to be constructed around Russell's abstract symbolic logic. According to this
program, all truly scientific knowledge must, first of all, be validated by
appeal to neutral empirical observations, on pain of being dismissed as
meaningless; and it must then be incorporated into the larger scheme of unified
science. (see also axiomatic method )
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The strongest
opposition to this Empiricist or Positivist strand has come, correspondingly,
from a Neo-Kantian school that has questioned the very possibility of
identifying the pool of theoretically neutral observations necessary for
substantiating or discrediting alternative theories in a strictly logical
manner. This Neo-Kantian strand in 20th-century philosophy of science was
inaugurated by the pioneering thinkers Heinrich Hertz (in electromagnetic wave
theory) and Ludwig Wittgenstein
(in philosophy of language). Rejecting Mach's central epistemological questions
about sensations and ideas, these men have started instead from Kantian
questions about the use of representations or models in the explanation of
phenomena. Hertz's treatise on The Principles of
Mechanics (1894), for instance, expounded Newtonian dynamics as a formal
representation that logically entailed empirical conclusions only insofar as the
phenomena concerned were already describable in terms drawn from the theory
itself; and Wittgenstein's Tractatus
Logico-Philosophicus (1922) extended Hertz's analysis to
provide a general philosophical theory of language as an instrument for the representation of facts. The
implications of this approach for the philosophical analysis and methodology of
science have been explored further by some of Wittgenstein's pupils and
successors, who have shifted the focus of discussion away from the verification
of scientific propositions to the establishment of scientific concepts and
theories; by highlighting the problem of conceptual change, they have revived
interest in the philosophical significance of the history of scientific ideas.
For, from this point of view, logical questions about the structure of
propositional systems must be joined by other, equally fundamental rational
questions about the manner in which different theoretical systems come to
succeed one another (see below Conceptual
change and the development of science ).
(see also Neo-Kantianism)
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During this same
period, the remarkable changes taking place within such sciences as theoretical
physics, biochemistry, and psychology have been provoking philosophical
discussions among scientists themselves. For instance, the displacement of
classical Newtonian physics by Heisenberg's quantum mechanics has stimulated a
new round of arguments about causality and determinism, with some people hailing
Heisenberg's Principle of Indeterminacy--which holds that the location of a
particle is intrinsically imprecise in the measure that its momentum is precise
(and vice versa)--as giving human free will the toehold that rigorous
19th-century determinism did not seem to allow. Progress in cellular and
subcellular physiology, moreover, has given rise to further rounds of debate in
the philosophy of biology. Claude Bernard, the foremost experimentalist of
19th-century medicine, had never managed to extend his analysis of regulatory
mechanisms, such as those of the nerves that control the size of blood vessels,
to cover the processes of embryology and morphogenesis (development of organic
forms); and, on this finer level, there had been a renewed deadlock, around the
years 1900-20, between the vitalism
of Hans Driesch, which
posited an almost "soul-like" reality that guides development, and the
mechanism of Jacques Loeb,
both experimental biologists with philosophical concerns. Once again, supporters
of neither extreme position could make out their case entirely; instead,
biologists have tended toward the mediating systemic conceptions first
introduced by Paul A. Weiss,
a distinguished developmental biologist, in the mid-1920s, and subsequently
developed in detail as applications of the new theories of cybernetics and
feedback, which conduct comparative studies of automatic control systems in the
nervous system and in electromechanical engineering. More recently still, the
development of molecular biology
has compelled scientists to reformulate the problem of morphogenesis
yet again--this time as the problem of seeing how the structural patterns of
nucleic acid macromolecules in the hereditary genetical material find a
structural expression in the developing body as a result of interacting with the
environment. At present, this question is still very largely unanswered. (see
also uncertainty principle) |
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Methodologically,
since 1940 one new centre of philosophical debate has developed, this time in
the behavioral sciences.
Ever since Descartes and Hobbes, there has been sharp disagreement about the
legitimacy of extending the methods and categories of physical science to the
sphere of the higher, distinctively human mental processes; and, even in the
1970s, theoretical psychologists were still far from agreed in their
explanations of human behaviour. Some psychologists insist that human actions
are subject to laws and mechanisms of the same kind as physical processes;
others deny that any direct analogy exists between rules of conduct and laws of
nature. Currently, this dispute is most lively in the psychology of language.
Behaviorists follow B.F. Skinner, an American psychologist, in rejecting any
distinctive class of mental laws and processes, whereas cognitive psychologists
and generative grammarians, led by Noam
Chomsky, argue that linguistic activities are creative and rule
conforming in respects that no behaviorist can explain. In sociology and
anthropology, equally, the 20th century has been a period of methodological
controversy. Here the unresolved conflict has to do with the significance of
history in the explanation of collective human behaviour. On one side, there is,
in sociology, a school of so-called structuralists or functionalists that
follows another American scholar, Talcott
Parsons; or, in anthropology, there are the British ethnologists A.R.
Radcliffe-Brown and Bronislaw
Malinowski, students of primitive mentality and behaviour, who regard
all of the cultural practices and social institutions that function within a
given community at any time as related together systematically within an overall
structure: to explain any one of those practices or institutions, they hold, it
is enough to show how it connects up with all of the other contemporaneous
aspects of the culture. On the other side, a more historically minded school,
notably the German "critical Marxists" (such as J?gen Habermas),
emphasizes the dynamic, developing character of social structures and
relationships. Here again, the methodological debate is still in progress, and
its eventual outcome cannot yet be clearly foreseen. (see also behaviourism)
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It is appropriate
at this point to define the recurrent problems that have played a central part
in the philosophical debate about science and the crucial elements that any
adequate philosophy of science must include in its account. From the beginning,
scientists themselves have been interested not merely in cataloging and
describing the world of nature as they find it but in making the workings of
nature intelligible with the help of compact and organized theories.
Correspondingly, philosophers of science are obliged to consider not merely
nature in isolation--as a mere assemblage of empirical facts, mutely waiting to
be discovered by man--but also the manner in which man himself perceives and
interprets those facts when bringing them within the grasp of an intelligible
theory and the respects in which the validity of the resulting theoretical ideas
(or concepts) is affected by that processing of the empirical data. (see also nature,
philosophy of) |
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Historically
speaking, the problems posed by this interaction of man and nature have been
complex and confused. Though philosophers of science face, even today, many of
the same questions that were already being debated in classical Athens, the
range and relevance of those questions has been greatly clarified in the
meanwhile. For instance, when philosophers in the 17th century analyzed the
nature and possible scope of a mathematical and experimental account of nature,
they helped to clear the ground for Newton to develop the intellectual program
and methodology of modern theoretical physics; while the subsequent
philosophical debate about natural and artificial classification similarly
cleared the ground for the scientific taxonomy of the Swedish systematist
Carolus Linnaeus and the theory of natural selection of Charles Darwin. Methodological
clarification in the philosophy of science has, in this way, repeatedly led to
creative advance in science itself and so given rise, in turn, to new experience
on which philosophers can draw in taking their methodological analyses further. |
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It is easy enough
to list the chief elements that must find a place in any philosophy of science,
but problems arise in mapping the relations between them. |
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First are the
empirical elements. The task of science is to explain actual events, processes,
or phenomena in nature; and no system of theoretical ideas, technical terms, and
mathematical procedures--or mathematical procedures alone--qualifies as
scientific unless it comes to grips with those empirical facts
at some point and in some way and helps to make them more intelligible. On the
one hand, the facts in question may be discovered by using observational
methods--i.e., by recording them as and when they occur naturally,
without employing any special contrivances affecting their occurrence. This
situation is, of course, the normal case in astronomy, in which the objects of
study cannot be influenced or controlled. Alternatively, they may be discovered
by using experimental
methods--i.e., by devising special equipment or apparatus with the help
of which those processes or phenomena are caused to occur on demand and under
specially controlled conditions. In that case, the scientist can attack
scientific problems--to use Kant's vivid metaphor--by "putting Nature to
the question," as in much of physics and fundamental biology. Either way, a
philosophical difficulty at once arises about the results of the scientist's
empirical studies: for he must ask how such raw empirical facts can be sifted,
stated, and described in a way that throws light on the scientist's own
theoretical problems. Do all empirical facts whatever serve as raw material for
science? Or is this true only of those that have been preselected for their
theoretical relevance--or even, to some extent, reshaped to ensure it? Is a
scientist concerned with every particular empirical event, as such, or only with
general phenomena or regularities recognizable in those events? Different
schools of philosophers treat this raw material in very different ways. |
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In the second
place, there are conceptual
elements. Every science employs its own characteristic abstractions,
terminology, and techniques of interpretation and explanation, which can be of
very different kinds. They may be ideal types, as in gas theory and parts of
sociology; conservation principles, as in dynamics and energetics; taxa, as in
biological systematics; particles or constituents, as in genetics and subatomic
physics; models or flow diagrams, as in econometric analysis. Such conceptual
elements are the intellectual keys by which phenomena are made intelligible, and
a most active philosophical debate has turned around the part they play in the
interpretation of phenomena. If, for instance, the idea of particles
or ultimate constituents of matter is regarded as a concept created by
scientists for the purpose of their own theoretical analysis, can an independent
existence then be claimed for such theoretical entities in the world of nature
itself? Or must all such ideas be regarded as fictions or constructs for which
the claim to reality goes no further than the paper on which the scientific
explanations are written? Similarly, if the theoretical descriptions of nature
arrived at in science are unavoidably idealized and abstract, does this imply
that the necessity attaching to arguments in, say, theoretical physics is itself
only an artifact, or by-product, of scientists' own procedures for interpreting
phenomena? Or can one, after all, speak of natural events themselves as
happening "of necessity"? |
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Finally, every
natural science includes also formal and mathematical elements or mathematical
elements alone. These may be mathematical algorithms, or procedures of
calculation, like those used in computational astronomy since Babylonian days,
or like the computer programs that are their 20th-century counterparts; or
geometrical constructions, as in certain branches of optics; or methods of
graphical analysis, such as those used in handling statistical data; or the
axiomatic systems by which, from classical times on, geometry and physics have
been organized into formal schemata of propositions bound together by logical
relations. Philosophers in the Platonic tradition give such formal elements
special consideration, viewing as authentically intelligible only those theories
the content of which can be presented explicitly in formal, and preferably in
mathematical, systems of propositions. Theories of this kind alone are
capable--as the seminal German logician Gottlob
Frege expressed it--of employing "concepts in their pure
form." Thus, 20th-century philosophers of science have devoted much time
and effort to the question: How far, and on what conditions, can other branches
of natural science (e.g., quantum mechanics or genetics) be cast in the
same definitive, axiomatic form as classical mechanics and electrical theory? Or
is this formal construction itself merely a human convenience, adopted to
simplify the handling of the empirical data, which reveals nothing more about
the underlying structure of nature itself? |
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Each of these three
groups of elements poses problems about which philosophers of science are still
in deep disagreement; and these differences of view can usefully be illustrated
by indicating the various approaches adopted by members of rival schools when
discussing each of the groups. At one extreme can be cited philosophers of a
radically Empiricist frame of mind, who regard it as important, above all, to
emphasize the empirical foundations of scientific knowledge; for them, the raw
facts of experience are primary and entitled to absolute respect. On this view,
general theoretical principles have authentic scientific content only when
interpreted as empirical generalizations about directly grasped empirical data;
and, correspondingly, abstract theoretical entities must be understood as
logical constructions from more fundamental elements that can be directly
identified in empirical experience. (This belief, of course, was the basis of
Mach's conclusion that submicroscopic atoms were merely intellectual fictions
and derived their scientific meaning entirely from the macroscopic sense
experiences that they were used to explain.) |
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At the other
extreme, philosophers of a fully Rationalist, or Cartesian, bent can be cited
who reject the idea that raw empirical facts, in and of themselves, display any
intelligible or law-governed relationships whatsoever--and still less any
necessary ones. For them, as for Plato, the scientist's bare experience of
nature is a disorganized aggregate, or flux, unless and until he is able to
discover some rational structure or principles relating these disconnected facts
to a larger, more intelligible whole. Rather than allow equal significance and
authority to every passing occurrence, the scientist, on this view, must be
highly selective in the observations to which he pays attention; indeed, the
very function of a well-designed experiment is now to create phenomena that can
illustrate the intelligible relationships that are the true concern of science
and so deserve the status of scientifically authenticated facts. |
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Both of these
approaches, the Empiricist and the Rationalist, emphasize valid and important
points; but, in their extreme forms, they give rise to difficulties that are
probably insuperable. As to the Empiricist approach, the credentials of any
scientific concept or theory certainly depend to a substantial extent on its
basis in empirical experience. Indeed, much has been learned about statistics,
the calculus of probabilities, and the design of scientific experiments from
careful analysis of the procedures by which empirical data are actually handled,
even before questions of theoretical interpretation were directly raised. Yet it
is questionable whether sense impressions alone could ever serve as evidence for
any scientific position, as Mach and the sense-data philosophers assumed. All
genuine scientific observations, as Kant
expressed it, have the form of judgments--i.e., are expressed in
statements answering questions formulated beforehand. It is probably an
exaggeration to insist that all legitimate theoretical statements in science
must be related in a strictly deductive manner to the everyday empirical
observations that they are used to explain; and it is a caricature to treat the
explanatory power of theoretical laws and principles, as for example in physics,
as no different in kind from that of such an elementary generalization as
"All robins' eggs are greenish blue." (see also deduction)
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As to the
Rationalist approach, one of the chief tasks for philosophers of science is
certainly to account for the rational interconnections that give scientific
explanations their characteristic intelligibility. In this respect, such men as Descartes,
Kant, and Hertz have deepened the philosopher's understanding of the scientific
enterprise by obliging him to recognize the ways in which the intellectual
organization of scientific theories rests on the scientist's own constructive
activities, rather than on the specific facts. Yet, it would again be misleading
to use this fact as an excuse for regarding physical theories--to echo a phrase
of Einstein's--as entirely "free creations of the human mind." While
the step from observations to theories does not rest on formal entailments
alone, it would be an equally serious counter-exaggeration to suggest that
theory construction is totally arbitrary or unconstrained by the imperative
demands of the specific problems to be solved. |
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The outstanding
task for most philosophers of science is, accordingly, to find an acceptable
middle way between the Rationalist and Empiricist extremes and thus to do
justice both to the empirical foundations of theories and to their internal
organization. The different emphases of philosophers commonly reflect, at most,
differences in their substantive preoccupations. Those who are interested (as
was Mill) in possible methods for developing the human or social sciences
naturally place most stress on the empirical basis of scientific knowledge.
Those who are familiar (as was Whewell) with the actual outcome of theory
construction in established sciences, such as physics, naturally underscore the
systematic coherence and structure of scientific understanding. Those who are
concerned with the nature and validity of historical understanding (as
Giambattista Vico was) likewise end by giving a very different account of
certainty and necessity from those (like Descartes) whose ideal of scientific
knowledge is a formal, mathematical one. |
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If the philosopher
comes to grips with the full complexity of the scientific enterprise, this
approach can lead him to a more exact understanding of the varied intellectual
problems of the natural and human sciences. Once it is recognized how different
are the kinds of questions arising within such diverse fields as quantum
electrodynamics and developmental biology, clinical neurology and historical
sociology, the goal of formulating a single scientific
method--with a universally appliable set of procedures and criteria
for judging new theories or ideas in all fields of science--may come to appear a
mirage. Yet the philosopher's legitimate insistence on generality has already
helped to promote important extensions and integrations of man's scientific
understanding. So again, he must now avoid taking too dogmatic a stand, either
for or against complete generality, bearing in mind Kant's warning that the
reason can hope to map its own proper boundaries only at the price of
occasionally overstepping them. |
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Along with the
three groups of elements already discussed, each phase in the scientific
enterprise--empirical, formal, and conceptual, or interpretative--involves its
own characteristic procedures. On the level of empirical observation and
description, three topics may be briefly touched upon, all of which are
discussed at greater length in other articles (see MEASUREMENT
SYSTEMS and articles on the basic
sciences). |
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First, there are
the procedures of measurement through which scientists arrive at quantitative
estimates of the variables and magnitudes considered in their theories. By now,
there is a well-developed body of knowledge upon which scholars are agreed about
many of the techniques and precautions to be employed in practice in the
measurement of empirical quantities, in the calculation of probable errors or
significant deviations, and so on. About the deeper significance of measuring
procedures and their outcomes, however, there are still unresolved philosophical
disputes. These disagreements reflect the same differences of approach already
noted. Thus, some philosophers regard any scientific theory concerned with
measurable (or quantifiable) magnitudes as intrinsically superior to a
qualitative (or, as they would say, an impressionistic) one, however rich and
well organized the latter may be. Others, by contrast, would argue that any
insistence on employing numerical measures at all costs, even in such a science
as, for example, systematic biology, can only lead the investigator to
misconceive the true nature of the problems involved. Again, philosophers of an
extremely Empiricist or Positivist persuasion have sometimes interpreted the
experimental procedures for measuring theoretical magnitudes in, for example,
physics as providing implicit definitions of the associated technical terms--the
so-called operational definitions--and have thus felt able to claim that the
logical entailments that the scientist is seeking between observations and
theories are established by linguistic fiat (see below Status
of scientific propositions and concepts or entities
). (see also measurement theory)
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Secondly, there are
statistical analytical
procedures for the design of scientific experiments. The mathematical techniques
employed for this purpose are, in fact, closely related to those involved in the
theories of measurement, probable error, statistical significance, and others.
In this area, the connection between philosophical discussions of inductive
logic and the practical procedures of working scientists is at its closest.
Whereas a religious scientist (Blaise Pascal), a Nonconformist minister (Thomas
Bayes), and an astronomer (Pierre, marquis de Laplace), all mathematicians as
well, analyzed the philosophical foundations of the modern calculus of
probabilities in the 17th and 18th centuries, 20th-century mathematicians and
inductive logicians have similarly explored the intellectual basis for the
design and interpretation of significant experiments; and, by now, the relevant
procedures form a full-fledged branch of mathematical
statistics with many valuable applications, particularly in fields such as
sociology and economics, in which large numbers of variables are involved. |
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Problems of
experimental design, however, can be stated clearly and unambiguously only in
situations in which questions of fundamental theoretical interpretations are not
actively at issue; e.g., in experiments to determine which of two
antibiotics is the more effective against a given infection or to learn whether
significant correlation exists between two known physical variables. As soon as
more fundamental questions of theory arise, however, the problems of
experimental design go beyond the scope of any purely statistical analysis.
Moreover, the same is true of computer-programming
procedures: the numerical data obtained from a straightforward scientific
experiment can in many cases be fed into a computer programmed to select the
graph or formula in best statistical accord with the data from among those
hypotheses conforming to a predetermined set of conceptual or interpretative
requirements; thus, in this sense, a computer can be used to perform inductive
inferences. Devising brand-new styles of conceptual or theoretical
interpretation, by contrast, involves extending or modifying present explanatory
procedures to satisfy novel intellectual requirements; and these
tasks call for something more than formal statistical or programming techniques.
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Finally, the
initial handling of the scientist's empirical data requires him to employ
procedures of systematic classification. The nature and validity of scientific
classification procedures and of the species, genera, families, and so on into
which scientists divide their empirical subject matter have been the subject of
a long and contentious debate. A long-standing philosophical deadlock between
supporters of natural and artificial classification systems was largely
broken--in zoological taxonomy,
at any rate--through the success of Darwin's theory of natural
selection. As Darwin showed, the species to which organic evolution
gives rise are neither eternally unchanging natural entities nor mere fictions
of the zoologist's arbitrary creation; considered as coherent, self-isolating
populations, they have a genuine though temporary reality that is preserved by
the contrary processes of variation and selection perpetuation. In some other
areas of thought, however, the preliminary identification and classification of
the empirical material still raises contentious philosophical questions. When
the sociologist theorizes about social groups or systems in the human sciences,
for instance, he has to decide what collections of men and institutions do, or
do not, fall under those general headings. Can objective tests be found for
identifying natural units of sociological
analysis? Or, is this choice of units merely set up for the sociologist's own
convenience? This uncertainty about the very subject matter of sociology is
itself an obstacle to the creation of an agreed-upon body of social theory; and
comparable difficulties can arise in anthropology, linguistics, and psychology
as well. It is, therefore, not surprising that some critics have even questioned
whether these disciplines can truly be called sciences. |
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The character of
these continuing difficulties underscores one point of general significance
about the relation of empirical evidence to scientific theories: though
philosophers may find it necessary to distinguish the empirical phases,
elements, and procedures of science from the theoretical ones analytically, it
does not follow that they can be kept wholly separate in actual practice.
Satisfactory measuring procedures, experimental designs, and systematic
classification principles are, no doubt, necessary preconditions for effective
theorizing; but they themselves are subject, in turn, to revision and refinement
in the light of subsequent theoretical considerations. In arriving at his
dynamical theories, for example, Newton had to begin by relying on older
commonsensical notions of effort, weight, and amount of movement; but he soon
replaced these by the more exact, theoretically defined concepts of force, mass,
and momentum, and this change reacted back onto the empirical procedures of
physics also. Likewise in other fields of science, the decision as to whether or
not the outcome of any empirical procedure is scientifically relevant or
significant soon ceases to be a purely empirical question, as theoretical
changes react back onto those empirical procedures and compel the scientist to
modify his manner of collecting and describing the supposedly raw data of
science. In this way, the empirical evidence by which his scientific conclusions
are justified rapidly loses its pure and theoretically neutral character. |
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In this section and
the next, those aspects of the scientific enterprise will be considered that
have dominated recent debate in the philosophy of science, viz., the formal
structures of scientific theory and the processes of conceptual change. It will
soon be clear that the philosophical problems to which these two aspects,
respectively, give rise are correlative and complementary--the one being static,
the other being dynamic. |
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Since 1920, most
analytical philosophers of science have explicitly based their program on a
presupposition inherited from Descartes and Plato, viz., that the intellectual
content of any natural science can be expressed in a formal propositional
system, having a definite, essential logical structure--what a leading American
philosopher of science, Ernest Nagel,
concisely called "the structure of science" in his book of that title
(1961). One immediate inspiration of this program was the work of David
Hilbert, a late 19th-century mathematician. To make the methods of
mathematical proof more explicit and more perspicuous and thus more rigorous,
Hilbert employed the techniques of formalization,
a reduction to relations while disregarding the nature of the relata, and
axiomatization, a tracing of entailments back to accepted axioms. |
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The same techniques
were taken over into the philosophy of mathematics by a pioneer German logician,
Gottlob Frege, and into symbolic logic by Bertrand Russell and his collaborator
Alfred North Whitehead; and, from 1920 on, the Viennese Positivists and their
successors attempted to employ them in the philosophy of science also, hoping to
demonstrate the validity of formal patterns of scientific inference by the
straightforward extension of methods already familiar in deductive logic. |
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According to the
resulting program, the primary task for the philosophy of science was to repeat
in quite general terms the kind of analysis by which, in the science of
mechanics, Heinrich Hertz,
the formulator of electromagnetic wave theory, had already sorted out the formal
aspects of science from its empirical aspects. The program was founded on the
expectation that it would be possible, first, to demonstrate the existence of
formal structures that were essential to any science, properly so-called, and
second, to identify the nature of scientific laws, principles, hypotheses, and
observations by their characteristic logical functions. Once this had been done,
rigorous formal definitions could then be given of validity, probability, degree
of confirmation, and all of the other evidential relations involved in the
judgment of scientific arguments. |
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The actual working
out of this program has involved complex and highly technical investigations, in
the course of which great ingenuity has been displayed--as, for instance, by an
outstanding philosophical semanticist and analyst, Rudolf
Carnap, in his system of inductive logic, for the criticism of
arguments in support of empirical generalizations, and by Hans Reichenbach, an
eminent German-American Positivist, in his analysis of probabilistic arguments.
So far, however, the program has yielded substantial results only as applied to
arguments expressed in an idealized formal symbolism modelled on the lower
functional calculus of mathematical logic. By contrast, little has been done to
show how one might extend the resulting formal procedures to arguments expressed
in the practical terminologies of working science. That extension, in fact,
raises difficulties and ambiguities that are so far unresolved and may prove
unresolvable. The goal of a purely formal analysis of scientific inference has
generated difficulties, for instance, by tempting logicians to play down
important differences between mere descriptive generalizations about natural
phenomena and the explanatory theories (laws, principles, etc.) that a scientist
develops to make those phenomena intelligible; and succumbing to this temptation
creates problems both within inductive logic and in its applications. |
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One distinguished
supporter of this program, Carl Hempel,
originally a member of the Berlin group (allied with the Vienna Circle), has
discussed what he calls the theoretician's dilemma: if the task of explaining
natural phenomena requires a proof that the character of those phenomena is
formally entailed by the conditions of their occurrence, taken together with
certain straightforward generalizations based on previous empirical experience,
and if those empirical generalizations include references to hypothetical
entities, then the theorist is faced with an invidious choice: for, in that
case, either his generalizations (his laws) do in fact provide a logical link
between the conditions of the phenomena and their actual occurrence and the
assumption of hypothetical entities is formally superfluous; or else they do not
succeed in doing so, and that assumption will not have strictly explained the
phenomena. Clearly, this dilemma can be evaded only by challenging the
identification of laws with generalizations and insisting that any appeal to
laws of nature always involves the scientist in reinterpreting natural
phenomena, not in merely generalizing about them. |
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Looking beyond the
internal structure of inductive logic, the dubious equation of scientific laws
with empirical generalizations has also been criticized on the ground that it
treats the content of those laws as matters of happenstance, far more accidental
or contingent than those expressed in any genuine law of nature. In the opposing
view, the explanatory force of, say, the physicist's law of inertia is totally
different from that of such a generalizing statement as "All swans are
white"; and one can learn nothing about the validity of actual physical
arguments unless his philosophical analysis respects that crucial difference. It
has not proved easy, however, to analyze the formal structure of the sciences in
any less abstract manner than that of the Viennese Positivists or to give a true
representation of the working language and arguments of science. In his Essay
on Metaphysics (1940), R.G. Collingwood, a British philosopher and historian, made one
striking attempt, in which the formal structure of intellectual systems was
explained in terms not of direct entailments between more or less universal
propositions but rather of mutual presuppositions between more or less general
concepts. In this account, the principle of inertia was not the most universally
true assertion in dynamics but was, rather, the most generally applicable
presupposition, or principle of interpretation. Such an account has the merit of
explaining why, within a particular science, certain formal patterns of argument
carry the apparent necessity that they do; but at the same time it lays itself
open to the charge of yielding too much to relativism and so
of destroying the objectivity of scientific knowledge by giving the impression
that the conceptual structures of science are imposed on phenomena by the
arbitrary choice of the scientific theorist himself. (see also induction)
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The late 1960s,
accordingly, saw a renewal of questioning about the original assumption, viz.,
that the entire intellectual content of a science can be captured in a
propositional or presuppositional system. Certain of the doubts about this
thesis revive criticisms put forward at the turn of the century by a U.S.
Pragmatist, Charles Sanders Peirce,
who argued that the logical status of the theoretical terms and statements in a
science is--in the nature of the case--subject to historical change as the
conceptual organization of the science develops. (This same insight has been
explored more recently by a U.S. logician, Willard
Quine, who rejects any attempt to classify statements within
scientific theories using the traditional hard-and-fast
dichotomies--contingent-necessary and synthetic-analytic--as fallacious and
dogmatic.) Other criticisms of the thesis go deeper. By focussing his
philosophical attention exclusively on the static formal structure of
propositional systems and, so, on the intellectual content of the sciences at
particular temporal cross sections in their development--they point out--the
philosopher is distracted from the complementary questions about the manner in
which the conceptual organization of a science changes and, so, from the
traditional claims of natural science to be a rational as well as a logical
enterprise. At this point in the debate, therefore, the spotlight shifts away
from the static problem of analyzing a science in static logical terms to the
historical problem of analyzing the dynamic processes of intellectual and
conceptual change. |
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The problem of
conceptual change has recently come back to the fore. The crucial question it
poses is: "What is a concept?" In the heyday of Logical Empiricism,
that question had largely been disregarded. Following the example of Frege, the
Viennese Positivists had condemned any tendency to regard the philosophy of
science as concerned with scientific thinking--which was in their view a matter
for psychologists--and had restricted themselves to the formal analysis of
scientific arguments. This preoccupation with logic was also reflected in their
view of concepts. To interpret a concept such as force as referring either to a
feeling of effort or to a mental image could lead, they argued, only to
confusion. Instead, the philosopher must equate concepts with the terms and
variables appearing in the propositional systems of science and define them, in
part by reference to their roles in the formal structures of those propositional
systems--thus fixing their systematic import--and in part by reference to the
specific events and phenomena they are used to explain--thus fixing their
empirical import. In the 1920s and 1930s, accordingly, all substantive
philosophical questions about the concepts of science were dealt with summarily:
they were simply translated into logical or linguistic questions about the
formal roles and empirical references of technical terms and mathematical
variables. |
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Once the philosophy
of science is approached more historically, however, those substantive questions
must be faced afresh in their own right. Rival scientific theories will now be
distinguished not merely as so many alternative formal systems, based on
different primitive terms and axioms, but also as alternative ways of organizing
the knowledge of nature, based on different explanatory techniques and modes of
representation. The distinctive features of different scientific concepts will
lie, as a result, not in their respective formal roles and empirical references
but in the styles of explanatory procedure involved in their application. Those
procedures may be of many different kinds: e.g., physical conservation
calculations, optical-ray diagrams, functional analyses, taxonomic
classifications, historico-evolutionary reconstructions, or dynamical axiom
systems. Correspondingly, they provide occasions for employing mathematical
formulas, or intuitively intelligible models, or genealogical trees, or other
styles of representation. In each case, however, the philosopher can describe
the conceptual organization of the resulting explanations in terms neither of
intuitive models nor of mathematical formulas and variables taken alone: what he
must now consider is the entire pattern of theoretical interpretation--models,
mathematics, and all. |
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Viewed from this
alternative standpoint, the philosophy of science will begin by identifying the
different styles of explanation characteristic of different sciences or of
different stages in a given science and will recognize how those differences in
explanatory style reflect the characteristic problems of different scientific
fields and periods. So considered, empirical generalizations and descriptive
classifications will serve to organize the empirical data of science in a
preliminary way; but serious theoretical interpretation can begin only after
that point. The central philosophical task now is to analyze, clearly and
explicitly, (1) the standards by appeal to which scientists have to decide
whether or not some interpretation is legitimate, justified, and conclusively
established and (2) the considerations that justify giving up one currently
accepted interpretation in favour of an alternative, novel one. |
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The first of these
questions is one that the Logical Empiricists set out to answer in their own
manner. They treated the empirical data and the theoretical principles of
science as being connected by purely logical relations and attempted to define
the required standards in terms of a formal theory of confirmation,
corroboration, or falsification. The second question is one that they never
seriously tackled. Instead, they assumed that one could, first, work out a
quantitative index of acceptability for individual theories taken separately
and, afterward, use this as a scale for measuring and comparing the merits of
rival theoretical interpretations. By now, however, it is evident that, when
biophysicists, say, abandon one theoretical approach in favour of another--as
being more fruitful from the standpoint of biophysics--the considerations that
lead them to do so are by no means analyzable in formal terms alone. On the
contrary, the ability of a biochemist, say, to judge whether or not such a
change in approach will effectively help to solve his theoretical problems is
one of the most severe assessments of his substantive grasp of what biochemistry
is about. |
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In this way, the
shift of attention from the propositions of science to its concepts
is making philosophers more aware of the extent to which theoretical
understanding involves the reinterpretation of empirical results, not merely
their formal transformation. Similarly, the problem of conceptual change is
raising questions about the processes by which theoretical interpretations
succeed one another and about the procedures of conceptual judgment that are
applied in the rational development of a science. These questions are currently
under active discussion, and several lines of attack are being considered, none
of which has finally established itself. |
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At one extreme,
there are some who still regard theoretical concepts and principles as organized
into compact, logical systems and who attempt to define the alternative
standpoints of different sciences as the consequences of different basic
premises or presuppositions. Having adopted this systematic approach, the
investigator then discovers that conceptual change at a fundamental level finds
adequate scope only through the replacement of one complete formal system by
another, distinct and separate successor system. As a result, fundamental
theoretical change is, in this view, intelligible only as the outcome of
thoroughgoing intellectual revolutions, in which one entire theoretical
system--axioms, principles, criteria of relevance, standards of judgment, and
all--is swept aside in favour of another. |
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Alternatively,
there are those who distinguish two different kinds of fundamental principles in
a science--marking off the basic theoretical assertions such as "Matter
consists of atoms combining into molecules" from its methodological maxims
and standards of judgment, such as "All physical phenomena are to be
explained in mechanical terms"--and who recognize fundamental conceptual
changes in the science as legitimate, just so long as they respect the
methodological maxims that are definitive of the science in question. In this
second view, conceptual changes of any depth in the intellectual substance of a
science will continue to be intelligible, provided only that the new views are
still governed by the established program and framework concepts of the science
in question. There will then be revolutions in science only when some entire
intellectual approach is discredited--e.g., that of 16th- and
17th-century iatrochemistry, which studied chemistry as a means of treating
disease--or when some entirely new science is created, with its own complete
system of interpretation--e.g., molecular biology. |
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At the other
extreme, there are some who doubt whether any sharp distinction can be drawn
between substantive theoretical assertions and maxims of methodological
procedure and who argue that all aspects of a natural science are alike open to
historical reconsideration and modification. The more specific the theoretical
doctrines and concepts being considered, the more risky they will be, and the
more readily they will be modified or abandoned or both. From this third point
of view, however, it is questionable whether any change, however drastic--even
the hybridization of crystallography, viral genetics, and biochemistry, which
led to the inauguration of molecular biology--is ever as discontinuous or
revolutionary as the two former views imply. Instead, the attempt may be made to
account for the procedures and processes involved in the historical development
of scientific concepts by using the same general form of theory on every
level--explaining innovation as requiring a selective choice between
intellectual variants of different kinds; and, in this way, the theory of
conceptual development can be brought into line with other historically based
theories of natural and cultural change. |
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Whichever
alternative is adopted, one point must be kept in mind: the moment that problems
about the changing theoretical organization of science begin to be treated in an
authentically developmental manner, philosophical inquiries are given a quite
new direction. This step compels one to view all questions about the logical
structure and propositional systems of science against a broader historical
background. In this new context the natural sciences are seen not as static
formal structures but as rational enterprises characterized by certain typical
intellectual procedures or movements. These basic procedures of intellectual
development in science are the topic to which attention is directed in the next
section. |
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2.1.4.1
Discovery and rationality.
In analyzing the
natural sciences for philosophical purposes as historically developing
enterprises, the question "What is it that makes the sciences
rational?" is raised in a new form: do the intellectual procedures that
scientists actually employ to investigate and explain natural phenomena have
definite and objective intellectual merits that make their adoption rationally
prudent, wise, and obligatory? In answering this question, philosophical opinion
has tended to polarize in recent years toward two extreme positions: on the one
hand, a formalist or positivist extreme, on the other, a romantic or
irrationalist one. (see also Romanticism)
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Given their
mathematical inspiration and preoccupations, both the Viennese Empiricists and
their successors in Britain and the United States have interpreted the
rationality of scientific procedures as depending solely on the formal validity,
or logicality, of scientific arguments. In their view, questions of rationality
can be raised about the scientist's work only at the final stage in his
inquiries--i.e., when he sets out, as the final outcome of his work, the
explicit explanatory arguments in support of his novel theories or
interpretations--only then, they declare, will there be anything about science
that is capable of being criticized in logical or philosophical terms. |
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It is therefore a
commonplace of recent Empiricist analysis in the philosophy of science that one
must distinguish at the very outset between discovery and justification. The
term discovery refers to all the stages in a scientific inquiry preceding the
formulation of the new explanatory arguments that are its final outcome. The
term justification refers, by contrast, to the demonstration that the formal
validity or explanatory power of those arguments justifies the scientist in
accepting their conclusions as scientifically validated or established. In this
view, the rational concerns of the philosopher of science are restricted solely
to this final phase of justification. All questions about the earlier stages--i.e.,
about discovery--are matters of mere psychology, not of serious philosophy.
As one widely accepted epigram expresses it, "There is no logic of
discovery"; and this distinction--given the equation of rationality within
logicality--seemingly invalidates all questions about the rationality of the
preliminary steps by which a scientist arrives at a discovery. |
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At the opposite
extreme, there are those, such as Michael
Polanyi, a Hungarian-born scientist and philosopher, and Arthur
Koestler, a novelist and journalist, who emphasize the parts played
by intuition, guesswork, and chance in scientific investigation, citing these as
evidence that theoretical achievement calls into play an intellectual creativity
superior to mere rationality. According to this anti-Positivist argument, the
modern scientist is a sleepwalker whose creative insight guides him to
intellectual destinations that he could never clearly see or state beforehand:
any excessive preoccupation with the rationality of scientific procedures, by
contrast, springs from a pedestrian desire to clip the wings of imagination and
to confine the scientist to stereotyped procedures, thus destroying the creative
fertility of science. Rather than subjecting scientific intuition to the barren
intellectual accountancy of the Positivists, the conclusion runs, one should
embrace a romantic anti-rationalism. |
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In each of these
extreme cases, however, the initial equation of rationality with logicality
demands closer examination. Certainly, the activity of investigation and
discovery can be examined with advantage from a psychological point of view as
it has been, in fact, by a French mathematician, Jacques
Hadamard, as well as from a philosophical point of view. Yet the
possibility of such psychological inquiries does not obviously prove, entirely
by itself, that procedures of intellectual investigation in science and
mathematics are essentially nonrational. Chance, for instance, may help to bring
relevant material to a scientist's attention. But chance--as has often been
remarked--favours the prepared mind, and it is fair to ask how far the scientist
acted rationally, after all, in picking out the items he did as being relevant
to his particular problems. Similarly, in the case of creative intuition and the
rest: once again, the man with the best trained mind can afford to give the
freest rein to his intellectual imagination because he will be best qualified to
appraise the rational context of his current problems and to recognize
significant clues, promising new lines of analysis, or possible answers to his
questions, as they come to mind. |
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Neither denigrating
the early phases of scientific inquiry as of merely psychological interest nor
overpraising them as exercises of creative imagination disposes therefore of the
philosophical problem that is here involved, viz., that of showing what makes
certain procedures of investigation more rational than others. To find a middle
way between formalism and irrationalism, it is necessary to look more closely at
the nature of the problems of scientific inquiry. If the improvement of
scientific concepts and theories depends on the development of more powerful
explanatory procedures, the philosophical analysis of discovery then requires
that one show what is essentially involved in devising such procedures, testing
them out, and determining the range of their application. This problem must be
dealt with, furthermore, not by a formal analysis of the resulting arguments
alone but first and foremost by establishing what tasks any novel explanatory
procedure in science can be required to perform, what demands its performance
can properly be asked to satisfy, and so what intellectual goals a scientist is
expected to be aiming at in all the phases of his investigations. Posed in these
alternative terms, the problem of scientific rationality becomes a problem of
showing how conceptual changes in science result in the introduction of novel
ideas, which are--in a phrase coined by Mach as early as 1910--"better
adapted, both to the facts and to one another." It is rational for older
scientific theories to be displaced by newer ones that are functionally
superior; and the task for philosophers of science is to demonstrate explicitly
in what such functional adaptedness consists. |
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At the present
time, many younger philosophers of science are actively analyzing the nature of
the problems of science in these terms. Significantly, most of these men have
had their own primary training within the natural sciences proper rather than in
formal logic or pure mathematics, for the task requires a much more detailed
analysis of the processes of intellectual innovation than has been customary
hitherto. In place of the simple dichotomy between discovery and justification,
for instance, it calls for a subdivision of the innovation process into a more
complex sequence of distinct stages; and at each stage both rational and causal
considerations are relevant. Thus, at the initial stage in any inquiry, a
scientist must decide which among all of the philosophically conceivable
variants from the current repertory of explanatory methods are to be taken
seriously at all; which, that is, are genuine possibilities. This preliminary
sorting of initially plausible from implausible innovations must be dealt
with--and dealt with in the most rational manner possible--long before any
question of justification arises. |
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This initial
sorting procedure is one about which scientists themselves also speak cogently
and eloquently. Far from deciding what novel suggestions are genuinely possible
or plausible on a purely psychological basis or by the exercise of some
mysterious, nonrational intuition, scientists will commonly explain their
reasons for accepting one set of conceptual variants rather than another as
deserving serious consideration. At the same time, such microanalyses of
scientific innovation must certainly leave room for causal as well as rational
questions. During certain periods in the historical development of science, for
instance, scientists have notoriously disregarded novel possibilities that later
turned out to hold a key to the solution of crucial theoretical difficulties.
Looking back at such periods, it is possible to reconstruct with care the
rational considerations that might have been advanced at the time to explain
this neglect; but even so, one is occasionally forced to conclude that the men
involved were prejudiced against those possibilities by factors external to
their sciences; e.g., by influences originating in the wider social,
cultural, or political framework of their time. Thus, Newton was particularly
afraid that his theory of material particles might be accused of supporting
Epicureanism, whereas Darwin concealed his private speculations about the
cerebral basis of mental activities because of public objections to Materialism.
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In analyzing the
microstructure of scientific problem solving, it is necessary, accordingly, to
resist any temptation to generalize prematurely. Scientific investigators
working in different fields, or at different times, apparently face theoretical
difficulties of quite different kinds. One must therefore begin by studying the
specific needs and tasks of each particular science, at one or another stage in
its evolution, separately--seeking to recognize, in each individual case, the
particular intellectual demands to be met by any new concept or theory if it is
to be successful. Eventually, the accumulated results of specific microanalyses
may bring the investigator to a point at which he can again afford to generalize
about all of the assorted theoretical problems confronting, say, physics and
about the broader intellectual demands to be met by successful theoretical
changes in a variety of scientific situations. At the present stage, however,
though philosophers of science still cannot afford to beg these questions, they
are compelled to conduct their analyses in a more piecemeal way--building up
their picture of scientific innovation and discovery by considering a wide range
of sample cases and working their way only gradually toward a more comprehensive
account of the problematics of the scientific enterprise. |
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If this situation
is true of the earlier stages in discovery, it is no less true in the case of
justification itself. Here again, from 1920 on, the debate in the philosophy of
science focussed predominantly on two sharply opposed positions, both of which
appear in retrospect to be excessively narrow. On the one hand, Empiricist
philosophers argued for a view that made prediction the crucial test of
scientific validity; on the other hand, philosophers of a more Rationalist
temperament saw coherence and scope as the crucial requirements. |
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For Empiricists,
the fundamental presupposition is that the facts justifying changes in
scientific ideas are both intellectually prior to the theories that are, in due
course, developed to explain them and also capable of being recognized
independently and in advance of all theory construction. Given this
presupposition, they regard prediction
and validation as the crucial and distinctive steps in
scientific procedure, arguing that, to establish the validity of any general
scientific proposition, it is necessary to show that the theoretical
generalization of which the validity is in question entails particular factual
statements that are borne out by independent empirical observations. This
validation process then involves two essential steps: (1) the formal step of
inferring novel predictions from the theory and (2) the empirical step of
comparing those predictions with the facts and so confirming the theory or
proving it false.
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On closer
inspection, both steps in the received Empiricist procedure face serious
difficulties, and these have lent strength--by reaction--to the alternative, constructivist
position. As to step (1), there appears to be no objection to the idea of
deducing particular factual predictions directly from theoretical hypotheses, so
long as one accepts the Empiricist interpretation of laws of nature as universal
empirical assertions on the same logical level as "All polar bears are
white." Once that interpretation is questioned, however, it is less clear
that direct deductive inferences from theory to fact are always practicable. On
the contrary, if theoretical laws and purely empirical reports are, in the
nature of the case, framed in terms of distinct and diverse sets of concepts, no
general procedure can be available for passing deductively from one to the
other. For the theory will then be a reinterpretation of the facts, not a mere
generalization from them. Similarly, with step (2), an empirical confrontation
of theories and facts gives rise to a more complex range of choices than those
implied by the Empiricist account. When faced with discrepancies between
prediction and observation, scientists certainly have to modify their
theoretical explanations; but this modification can normally be made in any of
several alternative ways. For instance, the theoretical relevance of a
particular observation may be questioned; or some alternative theoretical
interpretation may be put forward; or further refinements may be made within the
structure of the theory concerned--and all of this can be done before any
question arises of a direct and necessary conflict between the discordant
observation and the general theoretical doctrine under investigation. |
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The rival,
constructivist position derives its attractions from such objections as these.
This position follows lines of thought already sketched by the French
theoretical physicist Pierre Duhem at the turn of the century. On this account,
the essential test of a science is that it should provide coherent, consistent,
and wide-ranging theoretical organizations. Empirical facts will then be
recognized as scientifically relevant only to the extent that they exemplify
these interpretations and make them more discriminating. Thus, no single factual
observation can ever serve as a logically crucial experiment
and confirm or refute any one specific doctrine conclusively, taken apart from a
whole complex of theory and interpretation. What is at risk in any experiment or
observation, therefore, is
the whole body of the theory, together with the current conventions governing
its empirical application; and the more comprehensive a theory is, the more are
scientists free to vary the details of their specific applications of it, rather
than to accept any single counter-example as a challenge to its general
validity. (see also experimentation)
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If these two
philosophical approaches are reconsidered today against a broader and more
historical background, however, they no longer appear to be either as exhaustive
or as contradictory as they did in the 1920s and 1930s. By choosing suitable
illustrations, of course, one can make each position highly attractive and
plausible since, in one situation or another, the rational considerations that
carry genuine weight in the actual justification of novel scientific theories
include both predictive success and conceptual coherence. But the "Book of
Nature," as Galileo called it, is like Holy Scripture: it offers texts to
suit all occasions and purposes. And, on second thought, it can be argued that
both Empiricist and constructivist philosophers oversimplify the justification
process in science and the criteria by which scientists judge the validity of
novel concepts and theories. Far from there being any single or simple test of
validity, the question whether predictive success or coherence, simplicity,
historical authenticity, or mechanical intelligibility is the key
consideration--and in what sense of each ambiguous phrase--must be considered
afresh from case to case, with an eye to the specific demands of each new
scientific problem situation. |
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Within the
historically developing enterprise of science, intellectual problems arise of
many different types, depending both upon the kinds of subject matter under
investigation and upon the stage of development of the science concerned. In one
science and at one stage, particular weight may attach to a single unexpectedly
successful prediction: as when the wave theory of light led to the totally
unexpected discovery that a perfectly circular obstacle placed in front of a
point source of light produces a circular shadow having a bright spot at its
centre. In another science or at another time, however, it may be neither
practicable nor relevant to infer such specific predictions, and new theories
and concepts may be validated by considerations of quite other kinds. Even
within a single science such as physics, indeed, scientists are not faced at
every stage by problems and judgments of a single, uniform type. Instead, the
historical evolution of physics--down the centuries from Nicole Oresme, Galileo,
and Newton to Maxwell, Rutherford, and Heisenberg--has generated an entire
genealogy of varied problems; and the considerations bearing on the theoretical
difficulties facing physicists at different stages have themselves changed,
quite legitimately, along with the substantive concepts and theories of the
science. So, within the more complex framework of a developing rational
enterprise, the philosopher's task is no longer to impose any single or simple
criterion of intellectual choice upon scientific judgments of all kinds. Rather,
his task is to recognize how the rational considerations and criteria of
validity relevant to particular judgments vary with the theoretical problem
situations that provide their historical contexts. (see also science,
history of) |
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As one notable
illustration of the tug-of-war between logical and pragmatic issues in the
philosophy of science, the "unity
of science" movement may be cited. Under the vigorous leadership
of Otto Neurath, a polymath
sociologist and philosopher, this movement represented the high point in the
ambitions of Viennese Positivism between World Wars I and II; for the general
philosophical aims that motivated the search for a unified science are in
striking contrast with the specific problem-solving considerations that lead
working physicists to unify or integrate their theoretical concepts and explanatory
procedures in actual scientific practice. |
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Aside from the
primary test of predictive success, the Positivists of the Vienna
Circle also did allow--on their own terms--for the further
theoretical virtues of coherence and comprehensiveness. Their
logico-mathematical approach to the propositional structure of scientific
theories, however, led them to interpret this demand for coherent and
comprehensive theories in a formal sense. On their interpretation, a totally
unified body of scientific ideas would be a comprehensive, quasi-Euclidean
system of scientific theorems, based on a single set of general axioms,
postulates, and primitive propositions and applicable to natural phenomena of
all kinds. Given sufficiently all-embracing empirical generalizations as the
starting points of such a unified science, it would then be possible, in their
view, to deduce particular statements about all the phenomena covered by the
varied special sciences unified within its axiomatic scope. Taking the symbolic
logic of Russell and Whitehead as their formal core, philosophical advocates of
the unity of science then set out to construct, on a single axiomatic pattern, a
fully comprehensive account of nature capable of explaining (i.e., entailing)
all natural phenomena whatsoever. |
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At first glance,
this ambition seemed laudable and legitimate, but once again the Empiricist
program subsequently encountered unforeseen entanglements. The reasons for this
situation were not merely the discovery that the theoretical ideas employed
within different branches of a science (e.g., of mathematical physics)
are more resistant to conceptual integration than had originally been hoped (the
task of constructing a self-consistent relativistic theory of quantum
electrodynamics, for instance, is one that still defeats the physicists); but,
what is worse, it has now become apparent that several well-founded and properly
respected branches of scientific theory do not lend themselves to exposition in
a formal mathematical manner at all. Any satisfactory theory of organic
evolution, for instance, has an irreducibly historical dimension; and there is
no possibility of putting historical zoology on the sort of predictive basis
that Empiricists have demanded, still less of incorporating it into Neurath's
larger unified axiom system. Faced with this particular example, indeed, one
distinguished Empiricist philosopher, Carl
Hempel, has drawn a somewhat extreme conclusion, viz., that the
theory of natural selection is not really an explanation of organic evolution
at all--not even a bad one--but is merely an elaborate redescription of the
historical episodes concerned. Yet this is simply a roundabout way of conceding
that neither the historical problems nor the theoretical ambitions of
evolutionary zoologists conform to the quasi-mathematical pattern that the Logical
Empiricists have set out to impose on all of the natural sciences
alike in the interests of a longer term axiomatic unification. |
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If, on the other
hand, the demand for integration or unification is considered as a practical
problem of methodology, it will then be found that the scientists are facing
problems of a different and more pragmatic kind. The science of physiology poses
an interesting example because, within this field, the problem of reductionism--i.e.,
of whether all phenomena whatsoever can be reduced to physico-chemical terms
alone--has repeatedly drawn active debate. Since the time of Antoine Lavoisier,
who first explained correctly the process of combustion--i.e., since the
late 18th century and even before--there has been a methodological division of
opinion, involving, on the one hand, those chemists and physiologists who
dreamed of equating physiological functions with chemical reactions and planned
their program for biochemistry around that ambition and, on the other hand,
those clinical scientists and functionally minded physiologists who questioned
the legitimacy of this so-called physicalist program and insisted that
physiological phenomena displayed certain features or aspects inexplicable in
physio-chemical terms alone. The scientific issues in debate in this case have
never been concerned with formal matters of axiomatization and logical
integration alone: once again, they have involved substantive questions of
interpretation. Correspondingly, the provisional resolution of this dispute,
accomplished by Claude Bernard
in the mid-19th century, was not arrived at by constructing a single, unified
axiom system of biochemistry-cum-physiology. Rather, Bernard distinguished the
proper questions and concerns of the two sciences and demonstrated the
substantive character--and limits--of their mutual relevance. (see also biochemistry,
physiology) |
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Regarded as
specific, localizable processes within the main organs of the body, he argued,
all physiological phenomena do, indeed, come within the scope of the same
general physico-chemical laws and concepts as govern similar processes in
inorganic systems. Within the special micro-environments of the body, however,
those same general types of phenomena serve certain unique physiological
functions, having no inorganic counterparts; and, to this extent, special
problems and questions arise within physiology that cannot be exhaustively
translated into the language of inorganic physics and chemistry. Though
biochemistry and physiology in no sense conflict, there accordingly remains an
essential plurality in the explanatory aims of the two sciences; and this
plurality gives rise, in turn, to a corresponding plurality of methods and
concepts. |
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Yet even this
example does not yield conclusions from which one can safely generalize. Though
in certain respects the explanatory aims of physiology and biochemistry will,
most probably, always be distinct and separate, in other cases matters have gone
the other way. When, in 1873, the Scottish physicist James Clerk Maxwell, for
instance, integrated the previously independent sciences of electricity,
magnetism, and optics into the unified physics of electromagnetism, there was no
comparable division of opinion and no such methodological peace treaty was
needed. In this case it remained possible, after Maxwell's work as before, to
distinguish between straightforwardly electrical, magnetic, and optical
phenomena on the empirical level; but on a more general, theoretical level such
distinctions lost their earlier significance, and it ceased to be necessary to
keep the problems, methods, and explanatory categories of the three earlier
sciences separated. |
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To sum up: in the
methodological drive toward the unification of the sciences, as in the earlier
phases of discovery and validation, the intellectual temptation to generalize
prematurely exposes the philosopher to certain real dangers. In practice, the
case for unifying the theories and concepts of two or more sciences has to be
considered afresh in every instance, and it can rarely be decided in advance
whether or not such a unification will achieve anything useful for the sciences.
Instead, one has to analyze the practical demands of the current problems in the
different fields and see how far those requirements can be met by developing a
unified explanatory treatment for all of the special sciences in question. The
integration of theoretical concepts achieved in the process will not consist
solely in the formal running together of different propositional systems: more
typically, it will require the development of a whole new pattern of theoretical
interpretation. And, though it may be possible, in certain cases, to expound the
resulting theory in axiomatic form, it must be established, in each case
separately, whether or not this can be done. In this sense, conceptual and
methodological unification represents a genuine movement in the development of
scientific thought; but the logical form of the unified science towards which
the philosopher is working is not something that he can lay down definitively
before the event. |
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2.1.5.1
Status of scientific propositions and concepts or entities.
The section of this
article entitled Elements of
scientific enterprise examined,
first, the raw material (or elements) with which scientists have to work in
developing their theories about the operations of the natural world and, second,
the intellectual steps (or movements) by which they arrive at a scientific
understanding of nature. By way of summary, it is appropriate to consider
finally the main points of view about the intellectual status of the scientific
concepts and doctrines embodying the understanding of nature that have emerged
from the philosophical debate about science. Beginning with the epistemic status
of theoretical propositions in science, it is well to consider the different
claims that are made about the objectivity of their applications or their truth
or both. Then, turning to the ontological status of the scientific concepts or
entities, it is likewise necessary to consider the claims that are made about
the objectivity of their reference or of their meaning or both. In either case,
the purpose of a philosophical critique of science is to establish just how far
the content and reference of scientific knowledge can be regarded as a true
report about the actual structure and operations of nature and just how far they
represent, on the contrary, intellectual constructs or artifacts in terms of
which men have chanced, chosen, or found it desirable to organize their thoughts
about the structure and operations of nature. |
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Starting with the
epistemic status of scientific theories, three main views can be distinguished:
At one extreme is a strict Realist position, which underscores the factual basis
of all scientific knowledge and emphasizes the logical contingency that this
basis implies for all substantive propositions in science. In this view, all but
the most purely formal statements in science make assertions about how the world
of nature is constituted and operates in fact--as contrasted with all of those
alternative states of affairs that are clearly intelligible and so possible but
which turn out not to be true of the actual world. Seen from this Realist
standpoint, every proposition in science, from the most particular observational
report to the most general theoretical principle, simply reports a more or less
comprehensive empirical set of facts about nature and aspires to be an accurate,
objective mirror of the more or less universal facts about which it speaks. (see
also epistemology, realism)
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At the opposite
extreme, there is a strict conventionalist
position, which underscores the constructive role of the scientist's own theory
articulation and emphasizes the logical necessity that is thereby built into the
resulting conceptual structure. In this view, all but the most purely
observational statements in science reflect the patterns by which the scientist
shapes his conceptual picture of the world of nature--the patterns in terms of
which all states of affairs clearly conceivable on the basis of current ideas
have necessarily to be formulated. Seen from this conventionalist standpoint,
theoretical thermodynamics, say, determines the character of all possible worlds
consistent with the principles of energy conservation and entropy (or
randomness) increase: a world to which thermodynamics is not applicable will
then be not so much factually false as inconceivable in present terms. |
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Finally, a wide
range of intermediate views seeks to evade the central opposition between
Realists and conventionalists. One representative view of this kind, first made
popular by Mach toward the end of the 19th century, invoked Kant's attack on
things-in-themselves, viewing the attack as providing grounds for dismissing all
debates about reality and objectivity as inescapably barren and empty. In its
most developed form, this so-called operationalist position
encourages the philosopher to regard theoretical propositions in science as
meaningful only insofar as scientific practice includes specific
operations--either manual measuring operations, or computational
pencil-and-paper operations--in terms of which those propositions are given
operational meaning. Nothing is then to be read into scientific knowledge beyond
its operational meaning; in particular, scientists are not to be understood as
claiming or disclaiming anything about the reality or conventionality of the
states of affairs that they report. The idea of nature as a thing-in-itself is
thus eliminated, as being an intellectual superstition and an obstacle to better
scientific understanding, which survives from an earlier metaphysical era.
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Three main views
should here be distinguished. The central question is, now, whether the nouns
and noun phrases used as technical terms in the theoretical propositions of
science rely for meaning on any claim that they refer to objective, external
entities; and current approaches to this question parallel existing views about
the epistemological issues, viz., whether the propositions themselves rely for
their truth on a claim to be mirroring or reporting objective, external facts.
Here, too, the Realist interprets all of the chief technical terms of scientific
theory as the names of objective entities existing in nature independently of
all human theories and interpretations. In this view, entropy, say--a measure of
the increase in randomness that every total system undergoes--is a genuine,
objective magnitude that has, at all times, played a crucial part in the
operations of nature even though physicists have only recently had the wit to
discover it; and it just happens, correspondingly, to be the case--in those
parts of the cosmos that can be observed--that the total entropy of an isolated
system nowhere decreases. (see also Index: ontology)
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The instrumentalist,
for his part, regards all theoretical notions such as entropy as intellectual
fictions or artifacts created by the scientist's own theory construction and
quite distinct from the natural world of objects, systems, and phenomena that
scientific theories have to explain. No doubt, scientific theory and the
external reality of nature do come into contact on the everyday or empirical
level of tables and chairs, rocks and flowers. Given the intellectual tasks of
scientific theorizing, however, the resulting concepts are essentially abstract;
and any grasping after real entities, as the objective external reference of the
theoretical terms, reflects a plain misunderstanding of this theoretical
enterprise. |
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Meanwhile, the phenomenalist
repeats, in the case of the technical terms of science, the same agnostic
criticism as that offered by the operationalist in the case of its theoretical
propositions. In this view, it is simply a meaningless waste of time for
scientists to debate the existence of enduring theoretical entities, regarded as
external, objective things-in-themselves; just as it is similarly wasteful for
them to interpret scientific theories as making, or denying, similar claims
about the existence of objective, external states of affairs. Instead, the terms
and concepts of science are all to be understood as the product of so many
logical, or semantic, operations or constructions, and questions about their
real existence are to be swept aside as damaging metaphysical superstitions. |
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The arguments about
these rival ontological and epistemological views cannot be safely left or
judged without first looking more closely at the complex relationship between
the general analytical interests of philosophers and the more specific
intellectual concerns of working scientists themselves. For the degree to which
each view about the reality of scientific entities and facts can carry
conviction depends substantially on what branches of science are at issue. As
the focus of philosophical attention has shifted historically from one
scientific terrain to another, so, too, have the relative degrees of
plausibility of these rival positions varied. |
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Since the 1920s,
for instance, there has been a marked revival of philosophical discussion among
scientists working in several specialized fields--particularly, among physicists
concerned with the structure and development of quantum
mechanics. In epistemic terms, the statistical character of
quantum-mechanical explanations has prompted some fundamental questions about
the status and limitations of human knowledge.
Clearly, the extent and accuracy of human knowledge about nature are limited by
the modes of operation of scientific instruments. Is it not also possible,
however, that the significance of this statistical character lies at a deeper
level? Perhaps the relevant objective relationships and states of affairs in
nature itself are governed intrinsically by a merely probabilistic
causality and so are essentially indeterminate. Or is there a point to be
reached on the microphysical level at which any such distinction between
subjective human knowledge and the objective state of affairs has finally broken
down? The ontal implications of quantum mechanics have been as puzzling as the
epistemic. Is an electron,
say, a discrete particle that just happens to elude man's exact observation; is
it an essentially blurred wave bundle having no precise dynamical
characteristics; is it a concentration of probability, a mere theoretical
symbol, or what? Or must one set all these ontological questions aside as
lacking any significance for physics and as standing in the way of the
physicist's proper task, that of extending the direct explanatory power of
quantum-mechanical explanation itself? |
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Elsewhere, the
philosophical debate about science has taken on other specific forms. Just as in
Aristotle's natural philosophy the metaphysical controversy about Ideas and
essences was reflected in Aristotle's own methodological approach to biology and
to the study of the natural relations and classification of organisms, so once
again 20th-century reappraisals of traditional taxonomy--in the light of
evolution theory, genetics, and population dynamics--have been an occasion for
renewed philosophical debate. As a result, earlier disagreements about natural
and artificial classifications have been reformulated and have generated a new
dispute, about the possibility of basing taxonomy on a mathematical science of
phenetics--in which the defining properties of different species, genera, etc.
are all given quantitative numbers or measures--and so harnessing the technical
resources of modern computers to its purposes. |
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Similarly, in the
psychology of perception and
related fields, the extension of understanding in recent years at last has
permitted the framing of authentically empirical questions about perception and
cognition, which lend themselves to direct investigation instead of being
restricted to general a priori speculations. The result has been a theoretical
debate, the final outcome of which will have profound effects on both
philosophical epistemology and natural science. In areas of this debate where
even Mach was content to pose entirely general questions, in the philosophical
tradition of David Hume, about the role of sense impressions as the raw material
of all cognition and perception whatsoever, it is now clear that many
preliminary differences and complexities must be unravelled before one can hope
to recognize the truly operative questions in this field. Far from all modes of
knowledge and perception conforming to a single common pattern, man's sensory
and practical dealings with the world call into play a variety of perceptual
systems of which the operations justify no simple epistemological formula about
impressions and ideas, sense-data and logical constructions, or intuitions and
schemata. Thus, at the present time, the investigations of some physiologists,
psychologists, and cyberneticists are bringing man's sensory and cognitive
activities within the scope of natural science while at the same time preserving
a feeling for the more general philosophical problems and insights of such
philosophers as Locke and Leibniz, Hume and Kant, Helmholtz and Mach. |
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At this point, the
alliance between science and philosophy is simply carrying over into fields of
science that are areas of methodological perplexity today the same interactions
that were fruitful in earlier centuries within sciences having methods by now
well understood. These interactions are unlikely to vindicate finally any one of
the rival positions in the philosophy of science, whether ontological (Realist,
instrumentalist, or phenomenalist) or epistemological (Realist, conventionalist,
or operationalist). Probably such a vindication was, in any event, too much to
expect. For in all the different special sciences--both natural and
social--historical development eventually brings the investigator to a point at
which he is ready to operate with a variety of technical terms or entities
having very different logical characters and functions and at which his most
general theoretical propositions or principles display corresponding differences
in their logical status and implications. |
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So long as
philosophical discussion is confined within the limits of an artificial, ideal
language or propositional system, it is possible, perhaps, to continue posing
purely abstract, general dilemmas about, say, theoretical entities or
confirmation theory. But the bearing of such formal dilemmas on the actual
content of contemporary scientific thought is becoming increasingly unclear. In
debating the ontal status of theoretical entities, for instance, the question
must at some stage be faced whether that phrase is intended to cover such
notions as gene or pi-meson, species or cold front, momentum or superego, social
class or economic market. (Certainly, not all of these terms have identical
characters and functions.) In debating the epistemic status of scientific
theories, likewise, it must be made clear whether one has in mind,
say, the mathematical schema of quantum-mechanical field theory, the
populational analysis of natural selection, the microstructures and mechanisms
of molecular biology, the developmental sequences of cognitive psychology, the
labour theory of economic value, the general regularities of terrestrial
meteorology, or what. (Once again, not all of these theories have identical
kinds of status or implications.) |
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Philosophical
doctrines and approaches that carry great conviction when applied to the
theories and ideas of one science may--not surprisingly--lose all of their
plausibility when extended to other fields. Thus, an Empiricist analysis may
apply quite straightforwardly to meteorology, yet entirely misrepresent the
structure and implications of electromagnetic theory; while, in return, a
Neo-Kantian account of theoretical physics may lack any direct relevance, say,
to ideas about animal behaviour. Today as in classical Athens, analytical
clarification in the philosophy of science goes, in this respect, hand in hand
with methodological refinements in the sciences themselves. In retrospect, the
methodological insights of Aristotle the marine biologist and of Plato the
theoretical astrophysicist can be seen to have been complementary, rather than
incompatible. Similarly, today, the philosopher must look at rival positions in
the philosophy of science not merely as contradictory answers to technical
questions within philosophy itself but equally as complementary contributions to
the methodological improvement of theoretical understanding over the whole
varied range of different scientific fields. |
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This survey has
been concerned, almost exclusively, with philosophical problems and arguments
about the sciences regarded as sources of theoretical knowledge. In pitting
Realism against instrumentalism, mechanistic ideas against organicist ones,
divine knowledge against human fallibility, or Platonic
Ideas against Aristotelian
essences, the philosopher is in each case concerned with the intellectual
status, implications, and validity of certain general scientific concepts,
methods, or entities. To confine oneself entirely to these intellectual aspects,
however, would mean accepting a total abstraction of theory from practice and of
scientific ideas from their behavioral expression. Thus, along with the
present-day shift of emphasis from the physical to the human and social
sciences, one finds that all such abstract approaches are coming once again
under criticism, as over-intellectualizing the nature and implications of
science. |
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Some of these
attacks come from the neo-Marxist direction and reflect a traditional Marxian
insistence on the unity of theory and action. (It was not for nothing that Lenin
picked on Ernst Mach as a
special target for scorn.) Analogous criticisms, however, are also coming from
men with very different intellectual loyalties--e.g., from the urban
sociologist Lewis Mumford and from many contemporary Existentialists. In
conclusion, therefore, a concise discussion is here given of some of the views
about the relations between science and the rest of culture; i.e., about
the relevance of scientific knowledge to other spheres of experience and concern
and, conversely, about the significance of broader, practical considerations for
man's understanding of scientific theory itself. (see also Index: Marxism)
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The variety of
these views has always been very great. Their exponents have ranged all the way
from those who, like the energeticist Wilhelm Ostwald and the evolutionist
Julian Huxley--both of whom rooted ethics in nature--present scientific ideas
and procedures as rational panaceas for intellectual and practical problems of
all kinds to those who, like Pierre
Duhem and Carl von Weizs?ker, physicist and philosopher of nature,
both of whom are theists, deliberately limit the claims of science so as to
preserve a freedom of manoeuvre for ethics, for example, or theology. At each
stage, most advocates of extreme claims for science have been ontological
Realists; and, in strengthening their ontal and epistemic claims, they have also
staked a claim to overriding intellectual priority on behalf of scientific
knowledge, in contrast to other forms of experience. Similarly, those who would
restrict the broader cultural claims of science have tended to be
phenomenalists; and, in weakening their philosophical claims, they have also
attempted to limit the authority of science to its own intellectual concerns as
narrowly defined. |
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Whatever one's
general philosophical position with respect to the reality of scientific
knowledge and entities may be, however, there are other more practical questions
to be faced, questions about the specific implications of different scientific
ideas and beliefs for parallel fields of human action and experience. On this
point, one particular theme unites a wide range of radical critics of science,
including both Lewis Mumford, U.S. social critic, and the Existentialists. Just
as the Christian Dane S?en Kierkegaard, an early and seminal figure of
Existentialism, condemned Kant's universalized system of ethics for ignoring the
individuality of actual ethical problems and decisions, so today there is a
widespread reaction against any tendency to treat social or practical decisions
as technical matters, which can be left to the judgment of scientific or
technological experts. The general methods of technology may, indeed, represent
practical applications of the theoretical understanding arrived at by science;
but all individual decisions about putting those general techniques to use--e.g.,
in constructing an airport or power station--must be made not by appealing
to any general formula or rule of thumb but by balancing a whole range of
diverse considerations--economic and aesthetic, environmental and human, as well
as merely technical. |
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According to
another contemporary critique, the theoretical points of view adopted in natural
science are general and abstract, but the practical demands of sociopolitical
action and, a fortiori, of individual action, are concrete and
particular; and, by itself, this contrast places an immediate restriction on the
existential relevance of scientific ideas and engineering techniques. Such
scholars as Thomas Huxley, a versatile scientist and defender of evolution, or
Wilhelm Ostwald, a pioneer in electrochemistry, who viewed reality as
essentially energy, might argue in general, abstract terms for interpreting
ethical principles in evolutionary or thermodynamical terms if they pleased (so
the critics continue); but such abstract speculative arguments have no bearing
on the actual tasks of ethical decision and action. Here again, every ethical
choice involves a unique constellation of considerations and demands; and this
problem cannot be dealt with by appealing to any universal rule but must be
appraised on an individual basis, as and when it arises. |
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Others take a more
positive approach toward the contribution of science to an understanding of
human values. Without necessarily claiming to transform ethics itself into a
"science," they at any rate argue that the personal attitudes needed
for effective work in science--adventurous skepticism and critical
open-mindedness--have a wider relevance also to human conduct and social
affairs. Supposing only that social and political discussion were conducted in
this same tentative and critical spirit (they claim), its typical and deplorable
passion and confusion could be replaced by the more rational consideration of
the means required in order to achieve explicitly stated ends. While specific
scientific ideas and doctrines may not be enough to direct social and political
action by themselves, the scientific attitude may, nonetheless, have a profound
significance for social policy and individual ethics alike. |
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This contrast,
between existentially minded critics of the claim that science is all-embracing
and socially minded believers in the scientific attitude, may be epitomized by
referring to contemporary discussions about the social significance of science
itself. On the one hand, there has recently been a revival of explicitly
anti-scientific views, which had been more or less dormant since the time of
Blake, Johann Wolfgang von Goethe, and their successors in the Romantic
movement. Supporters of this anti-science position point to the
central role of military technology in the financial support of 20th-century
scientific research and dismiss the average scientist's plea that he is not
responsible for the uses to which his ethically neutral discoveries are put, as
pallid and insincere. On the contrary (they argue), there is a long-standing and
unholy alliance linking the collective institutions of the scientific and
technological professions to the economic, industrial, and political powers that
be. Faced with the fruits of this historical union (they conclude), it is time
that scientists acknowledged their social responsibilities; and, failing better
institutional controls, the outcome of this moral self-scrutiny may well prove
to be a moratorium on further scientific research. Perhaps man already knows too
much for his own good and needs to digest the significance of his existing stock
of knowledge much further before adding to it and so widening yet again the gulf
between theoretical knowledge and practical wisdom. (see also morality)
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On the other hand,
there are those who recognize science as playing a crucial role in modern
society, but who go on to draw the opposite conclusion. Rather than putting a
stop to science (these men would argue), its scope should be broadened; that is,
scholars should be studying and understanding better the manner in which science
serves as an element in the larger social order--perhaps by developing more
adequate analyses of the social structure or perhaps by a large-scale extension
of the methods of operations research. Aside from anything else (they point
out), a moratorium on science is as impracticable as a moratorium on sin. It
could be enforced only if political unanimity prevailed to an unimaginable
degree among scientists. In the absence of such enforcement, liberal-minded
countries will merely put themselves at a needless disadvantage--both economic
and military--as compared with totalitarian states. Instead of pursuing this
will-o'-the-wisp, scholars should put more effort into the task of understanding
both the social preconditions of effective scientific development and the
economic and political priorities involved in the practical application of
scientific research. |
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As compared with
the controversies of earlier centuries, the debate between science and religion
is curiously muted today. There seems little room nowadays for the theological
passions that engulfed the discussion of Copernicus' new planetary theory, James
Hutton's history of the Earth, or Darwin's theory of natural selection; and one
would hesitate to speak any longer, as so many of our forefathers did, of
warfare between science and religion as unavoidable. It is true that a few
partisan writers can still find it a perplexing problem to decide such issues as
whether the existence of life on other worlds would require a re-enactment there
of the Christian fall and redemption or can insist--conversely--that the results
of astronautical exploration refute any religious belief that God is an Old Man
up in the sky. For most people, however, such questions have so far lost their
earlier bite that they appear, by now, quite na?e. |
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What is the reason
for this change? In earlier times, the term cosmology embraced not only the
structure of the astronomical cosmos and the origins of the human species but
also the religious significance of man's place in nature. Contemporary
theologians, by contast, see physics and biology as having much less bearing on
man's religious attitudes and preoccupations than their predecessors had
supposed that they had. As a result, men's earlier ambition to construct a
single, comprehensive world view, embracing the essential truths of both science
and religion, no longer plays the active part in intellectual life that it
formerly did. The only branches of science still capable of provoking vigorous
theological debate, even now, are the human, rather than the natural sciences.
The implications of Freudian psychology for the doctrine of grace and the use of
psychedelic drugs for inducing quasi-mystical experiences are topics for live
discussion today, in a way that evolution, astrophysics, and historical geology
no longer are. |
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This change of
focus has been accompanied by a change in ideas about the intrinsic limits of
science. It was formerly assumed that the boundaries between science and other
aspects of human experience could be defined by marking off certain types of
subject matter as essentially closed to scientific investigation. To one
generation, the heart of this forbidden territory was the mind; to another, it
was life; to a third, the creation. In this view, something in the essential
nature of mental or vital activities, or in the origins of the present order of
nature, made it impossible to treat these as phenomena open to study and
explanation by the rational methods and intellectual procedures available to
science. In fact, this view always had defects, from both the scientific and the
theological points of view. To scientists, it seemed to impose an arbitrary
restriction on their sphere of operations and so acted as a standing challenge
and irritation. For theologians, it had the disadvantage of placing the
essential claims of religion, so to speak, on a sandbank, where they risked
being submerged in time by the rising tide of scientific knowledge. So, by tacit
consent, the essential limits of science are now defined in quite different
terms. These limits are now identified by recognizing that the character of
scientific procedures themselves places restrictions on the relevance of their
results. A scholar may choose to study whatever objects, systems, or processes
he may please, but only certain of the questions that he asks about them will be
answerable in the general, theoretical terms characteristic of science. |
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This change of
approach may not have made the substantive problem--that of delimiting the
frontiers of science exactly at all points--very much easier to deal with than
it was before, but it has one genuine merit: it respects the crucial fact, to
which attention has been drawn at several points in this present survey, that
the distinctive features of science lie not in the types of object and event to
which the scientist has access but in the intellectual procedures that his
investigations employ and so in the kinds of problem that lend themselves to a
scientific solution. |
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(S.E.T.) |
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