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3 MODERN SCHOOLS
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As a philosophical ideology and
movement, Positivism first assumed its distinctive features in the work of the
French philosopher Auguste Comte, who also named
and systematized the science of sociology. It then developed through several
stages known by various names, such as Empiriocriticism, Logical
Positivism, and Logical Empiricism, and
finally, in the mid-20th century, flowed into the movement known as Analytic and
Linguistic philosophy. |
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The basic affirmations of Positivism are
(1) that all knowledge regarding matters of fact is based on the
"positive" data of experience, and (2) that beyond the realm of fact
is that of pure logic and pure mathematics,
which were already recognized by the Scottish Empiricist and Skeptic David
Hume as concerned with the "relations of ideas" and, in a later
phase of Positivism, were classified as purely formal sciences. On the negative
and critical side, the Positivists became noted for their repudiation of metaphysics;
i.e., of speculation regarding the
nature of reality that radically goes beyond any
possible evidence that could either support or refute such
"transcendent" knowledge claims. In its basic ideological posture,
Positivism is thus worldly, secular, antitheological, and antimetaphysical.
Strict adherence to the testimony of observation and experience is the
all-important imperative of the Positivists. This imperative is reflected also
in their contributions to ethics and moral philosophy, and most Positivists have
been Utilitarians to the extent that something
like "the greatest happiness for the greatest number of people" was
their ethical maxim. It is notable, in this connection, that Auguste Comte was
the founder of a short-lived religion, in which the object of worship was not
the deity of the monotheistic faiths but humanity. (see also epistemology,
mathematics, philosophy of, Skepticism) |
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There are distinct anticipations of
Positivism in ancient philosophy. Though the relationship of Protagoras--a
5th-century-BC Sophist--for example, to later Positivistic thought was only a
distant one, there was a much more pronounced similarity in the classical
Skeptic Sextus Empiricus, who lived at the turn
of the 3rd century AD, and in Pierre Bayle, his
17th-century reviver. Moreover, the medieval Nominalist William
of Ockham had clear affinities with modern Positivism. An 18th-century
forerunner who had much in common with the Positivistic antimetaphysics of the
following century was the German thinker Georg
Lichtenberg. |
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Positivism clearly has its proximate
roots, however, in the French Enlightenment,
which stressed the clear light of reason, and in the 18th-century British
Empiricism, particularly that of Hume and of Bishop George
Berkeley, which stressed the role of sense experience. Comte was
influenced specifically by the Enlightenment Encyclopaedists
(such as Denis Diderot, Jean d'Alembert, and others) and, especially in his
social thinking, was decisively influenced by the founder of French Socialism, Claude-Henri,
comte de Saint-Simon, whose disciple he had been in his early years and
from whom the very designation Positivism stems. |
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Comte's Positivism was posited on the
assertion of a so-called law of the three phases (or stages) of intellectual
development. There is a parallel, as Comte saw it, between the evolution of
thought patterns in the entire history of man, on the one hand, and in the
history of an individual's development from infancy to adulthood, on the other.
In the first, or so-called theological, stage, natural phenomena are explained
as the results of supernatural or divine powers. It matters not whether the
religion is polytheistic or monotheistic; in either case, miraculous powers or
wills are believed to produce the observed events. This stage was criticized by
Comte as anthropomorphic; i.e., as
resting on all-too-human analogies. Generally, animistic explanations--made in
terms of the volitions of soullike beings operating behind the appearances--are
rejected as primitive projections of unverifiable entities. (see also theology,
religion, philosophy of, nature,
philosophy of) |
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The second phase, called metaphysical,
is in some cases merely a depersonalized theology: the observable processes of
nature are assumed to arise from impersonal powers, occult qualities, vital
forces, or entelechies (internal perfecting principles). In other instances, the
realm of observable facts is considered as an imperfect copy or imitation of
eternal ideas, as in Plato's metaphysics of pure Forms. Again, Comte charged
that no genuine explanations result; questions concerning ultimate reality,
first causes, or absolute beginnings are thus declared to be absolutely
unanswerable. The metaphysical quest can lead only to the conclusion expressed
by the German biologist and physiologist, Emil du
Bois-Reymond: "Ignoramus et
ignorabimus" ("We are and shall be ignorant"); it is a
deception through verbal devices and the fruitless rendering of concepts as real
things. |
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The sort of fruitfulness that it lacks
can be achieved only in the third phase, the scientific, or
"positive," phase--hence the title of Comte's magnum opus: Cours de philosophie positive (1830-42;
The Positive Philosophy of Auguste Comte, 1853)--because
it claims to be concerned only with positive facts. The task of the sciences,
and of knowledge in general, is to study the facts and regularities of nature
and society and to formulate the regularities as (descriptive) laws;
explanations of phenomena can consist in no more than the subsuming of special
cases under general laws. Mankind reached full maturity of thought only after
abandoning the pseudoexplanations of the theological and metaphysical phases and
substituting an unrestricted adherence to scientific method. (see also science,
philosophy of, natural law) |
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In his three stages Comte combined what
he considered to be an account of the historical order of development with a
logical analysis of the levelled structure of the sciences. By arranging the six
basic and pure sciences one upon the other in a pyramid, Comte prepared the way
for Logical Positivism to "reduce" each level to the one below it. He
placed at the fundamental level the science that does not presuppose any other
sciences--viz., mathematics--and then ordered the levels above it in such a way
that each science depends upon, and makes use of, the sciences below it on the
scale: thus arithmetic and the theory of numbers are declared to be
presuppositions for geometry and mechanics, astronomy, physics, chemistry, biology
(including physiology), and sociology. Each
higher level science, in turn, adds to the knowledge content of the science or
sciences on the levels below, thus enriching this content by successive
specialization. Psychology is conspicuously
missing in Comte's system of the sciences. Anticipating some ideas of
20th-century Behaviourism and physicalism,
Comte assumed that psychology should become a branch of biology (especially of
brain neurophysiology), on the one hand, and of sociology, on the other. As the
"father" of sociology, Comte maintained that the social sciences
should proceed from observations to general laws, very much as (in his view)
physics and chemistry do. He was skeptical of introspection in psychology, being
convinced that, in attending to one's own mental states, these states would be
irretrievably altered and distorted. In thus insisting on the necessity of
objective observation, he was close to the basic principle of the methodology of
20th-century Behaviourism. |
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Among Comte's disciples or sympathizers
were Cesare Lombroso, an Italian psychiatrist and criminologist, and Paul-Emile
Littré, J.-E. Renan, and Louis Weber. |
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Despite some basic disagreements with
Comte, the 19th-century English philosopher John Stuart
Mill, also a logician and economist, must be regarded as one of the
outstanding Positivists of his century. In his System of Logic (1843), he developed
a thoroughly Empiricist theory of knowledge and of scientific reasoning, going
even so far as to regard logic and mathematics as empirical (though very
general) sciences. The broadly synthetic philosopher Herbert
Spencer, author of a doctrine of the "unknowable" and of a
general evolutionary philosophy, was, next to Mill, an outstanding exponent of a
Positivistic orientation. |
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The influences of Hume and of Comte were
also manifest in important developments in German Positivism, just prior to
World War I. The outstanding representatives of this school were a philosophical
critic of the physics of Newton, an Austrian, Ernst
Mach, who was also an original thinker as a physicist and excelled as a
historian of mechanics, thermodynamics, and optics, and Richard Avenarius,
founder of a philosophy known as Empiriocriticism. |
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Mach, in the introductory chapter of his
book Beiträge
zur Analyse der Empfindungen (1886; Contributions to the Analysis of the Sensations, 1897), reviving the
Humean antimetaphysics, contended that all factual knowledge consists of a
conceptual organization and elaboration of what is given in the elements; i.e.,
in the data of immediate experience. Very much in keeping with the spirit of
Comte, he repudiated the transcendental Idealism
of Kant. For Mach, the most objectionable
feature in Kant's philosophy was the doctrine of the Dinge
an sich--i.e., of the
"things-in-themselves"--the ultimate entities underlying phenomena,
which Kant had declared to be absolutely unknowable though they must
nevertheless be conceived as partial causes of man's perceptions. Hermann
von Helmholtz, a wide-ranging scientist and philosopher and one of the
great minds of the 19th century, by contrast, held that the theoretical entities
of physics are, precisely, the
things-in-themselves--a view which, though generally Empiricist, was thus
clearly opposed to the Positivist doctrine. Theories and theoretical concepts,
according to the Positivist understanding, were merely instruments of
prediction. From one set of observable data, theories formed a bridge over which
the investigator could pass to another set of observable data. Positivists
generally maintained that theories might come and go, whereas the facts of
observation and their empirical regularities constituted a firm ground from
which scientific reasoning could start and to which it must always return in
order to test its validity. In consequence, most Positivists were reluctant to
call theories true or false but preferred to consider them merely as more or
less useful. (see also sense-datum,
thing-in-itself) |
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The task of the sciences, as it earlier
had been expressed by the German physicist Gustav
Kirchhoff, was the pursuit of a compendious and parsimonious description
of observable phenomena. Concern with first causes or final reasons was to be
excluded from the scientific endeavour as fruitless, or hopeless (if not
meaningless). Even the notion of explanation became suspect and was at best
taken (as already in Comte) to be no more than an ordering and connecting of
observable facts and events by empirically ascertainable laws. |
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Mach and, along with him, Wilhelm
Ostwald, the originator of physical chemistry, were the most prominent
opponents of the atomic theory in physics and
chemistry. Ostwald even attempted to derive the basic chemical laws of constant
and multiple proportions without the help of the atomic
hypothesis. To the Positivist the atom, since it could not be seen, was to be
considered at best a "convenient fiction" and at worst an illegitimate
ad hoc hypothesis. Hans Vaihinger, a
subjectivist who called himself an "idealistic Positivist," pursued
the idea of useful fictions to the limit, and was convinced that the concept of
the atom, along with the mathematical concepts of the infinite and the
infinitesimal, and those of causation, free will, the economic man, and the
like, were altogether fictitious, some of them even containing internal
contradictions. |
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The anti-atomistic strand in the thought
of the Positivists was an extreme manifestation of their phobia regarding
anything unobservable. With the undeniably great success of the advancing
microtheories in physics and chemistry, however, the Positivist ideology was
severely criticized, not only by some contemporary philosophers but also by
outstanding scientists. The Austrian Ludwig Boltzmann
and the German Max Planck, for example, both
top-ranking theoretical physicists, were in the forefront of the attack against
Mach and Ostwald. Boltzmann and Planck, outspoken Realists, were deeply
convinced of the reality of unobservable
microparticles, or microevents, and were clearly impressed with the ever-growing
and converging evidence for the existence of atoms, molecules, quanta, and
subatomic particles. Nevertheless, the basic Positivist attitude was tenaciously
held by many scientists, and striking parallels to it appeared in American Pragmatism
and instrumentalism; in parts of the work of the Pragmatists Charles Sanders
Peirce, William James, and John Dewey, there is a philosophy of pure experience
essentially similar to that of Mach. |
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Though Richard
Avenarius has not become widely known, he too anticipated a good deal of
what the American Pragmatists propounded. His Positivism, like that of Mach,
comprised a biologically oriented theory of knowledge. From the needs of
organisms in their adaptation to the exigencies of their environment develop the
conceptual tools needed for prediction of future conditions. In Avenarius' view,
the raw material of the construction of the concepts of common sense and of the
sciences, however, was "the given"; i.e., the data of immediate sensory experience. Just as Mill in the
19th century considered ordinary physical objects as "permanent
possibilities of sensation," so Mach and Avenarius construed the concepts
pertaining to what men commonsensically regard as the objects of the real world
as "complexes of sensations." Thus, it was maintained that a stone,
for example, is no more than a collection of such sensory qualities as hardness,
colour, and mass. The traditional assumption that there must be an underlying
substance that has these properties was repudiated. To the question "What
would be left over if all of the perceptible qualities were stripped (in
thought) away from an observable object?" these Positivists answered:
"Precisely nothing." Thus the concept of substance
was declared not only superfluous but meaningless as well. (see also sense-datum) |
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In similar fashion, the concept of
causation was explicated not as a real operating principle but as regularity of
succession or as functional dependency among observable or measurable variables.
Because these dependencies are not logically necessary, they are contingent and
ascertained by observation, and especially by experimentation and inductive
generalization. |
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The Newtonian
doctrine according to which space and time are absolute or substantive realities
had been incisively criticized by the 17th-century Rationalist Gottfried
Leibniz and was subjected by Mach to even more searching scrutiny. While
Leibniz had already paved the way for the conception of space and time as
exclusively a matter of relations between events, Mach went still further in
attacking the arguments of Newton in favour of a dynamic and absolute space and
time. In particular, the inertial and centrifugal forces that arise in
connection with accelerated or curvilinear motions had been interpreted by
Newton as effects of such motions with respect to a privileged reference medium
imagined as an absolute Cartesian mesh system graphed upon a real space. In a
typically Positivistic manner, however, Mach found the idea quite incredible.
How, he asked, could an absolutely empty space have such powerful effects? Mach
conjectured that any privileged reference system must be generated not by an
imperceptible grid but by material reality--specifically, by the total mass of
the universe (galaxies and fixed stars), an idea that later served as an
important starting point for Einstein's general
theory of relativity and gravitation. (see also classical mechanics, cosmology
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The Positivist theory of knowledge, as
proposed by Mach and Avenarius, impressed many scholars, most notable among whom
was probably the leading British logician and philosopher Bertrand
Russell in one of the earlier phases of his thought. In a work entitled Our
Knowledge of the External World (1914), Russell analyzed the concept of
physical objects as comprising classes of (perceptual) aspects or perspectives,
an idea that later stimulated the work of Rudolf Carnap,
an outstanding philosophical semanticist and Analyst, entitled Der
logische Aufbau der Welt (1928; The
Logical Structure of the World, 1967). Mach remained the most influential
thinker among Positivists for a long time, though some of his disciples, like
Josef Petzoldt, are now largely forgotten. But The
Grammar of Science (1892), written by Karl
Pearson, a scientist, statistician, and philosopher of science, still
receives some attention; and in France it was Abel Rey, also a philosopher of
science, who, along the lines of Mach, severely criticized the traditional
mechanistic view of nature. In the United States, John Bernard Stallo, a
German-born American philosopher of science (also an educator, jurist, and
statesman), developed a Positivistic outlook, especially in the philosophy of
physics, in his book The Concepts and
Theories of Modern Physics (1882), in which he anticipated to a degree some
of the general ideas later formulated in the theory of relativity and quantum
mechanics. |
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A first generation of 20th-century
Viennese Positivists began its activities, strongly influenced by Mach, around
1907. Notable among them were a physicist, Philipp Frank, mathematicians Hans
Hahn and Richard von Mises, and an economist and
sociologist, Otto Neurath. This small group was
also active during the 1920s in the Vienna Circle
of Logical Positivists, a seminal discussion group of gifted scientists and
philosophers that met regularly in Vienna, and in the related Berlin Society for
Empirical Philosophy. |
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These two schools of thought, destined
to develop into an almost worldwide and controversial movement, were built on
the Empiricism of Hume, on the Positivism of Comte,
and on the philosophy of science of Mach. Equally important influences came from
several eminent figures who were at the same time scientists, mathematicians,
and philosophers--G.F. Bernhard Riemann, the author of a non-Euclidean geometry;
Hermann von Helmholtz, a pioneer in a broad range of scientific studies;
Heinrich Hertz, the first to produce electromagnetic waves in his laboratory;
Ludwig Boltzmann, a researcher in statistical mechanics; Henri Poincaré,
equally eminent in mathematics and philosophy of science; and David Hilbert,
distinguished for his formalizing of mathematics. Most significant, however, was
the impact of Albert Einstein, as well as that of the three great mathematical
logicians of the past 100 years--the ground-breaking German Gottlob Frege and
the authors of the monumental Principia Mathematica (1910-13), Bertrand Russell and Alfred North
Whitehead. |
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The confluence of ideas from these
sources and the impressions that they made upon the Vienna and Berlin groups in
the 1920s gave rise to the philosophical outlook of Logical Positivism--a label
supplied in 1931 by A.E. Blumberg and the Minnesota philosopher of science
Herbert Feigl. The leader of the Vienna Circle between 1924 and 1936 was Moritz
Schlick, who in 1922 succeeded to the chair (previously held by Mach and
Boltzmann) for the philosophy of the inductive sciences at the University of
Vienna. By 1924 an evening discussion group had been formed with Schlick, Hans
Hahn, Otto Neurath, Victor Kraft, Kurt Reidemeister, and Felix Kaufmann as the
prominent active participants. The most important addition to the circle was
Rudolf Carnap, who joined the group in 1926. One of the early activities was the
study and critical discussion of the Tractatus
Logico-Philosophicus (1922) of Ludwig
Wittgenstein, a seminal thinker in Analytical and Linguistic
philosophy. It seemed at the time that the views of Carnap and
Wittgenstein, although they had been formulated and elaborated quite
differently, shared a large measure of basic agreement. Parallel, but not
completely independent, developments occurred in the Berlin group, in which Hans
Reichenbach, Richard von Mises, Kurt Grelling, and Walter Dubislav were the
leading spirits. |
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Both the Vienna and Berlin groups
consisted mainly of philosophically interested scientists or scientifically
trained and oriented philosophers. Schlick had already anticipated some of the
basic epistemological tenets of the groups in his Allgemeine
Erkenntnislehre (1918; "General Theory of Knowledge"). But the
philosophical outlook was sharpened and deepened when, in the late 1920s, the
Viennese Positivists published a pamphlet Wissenschaftliche
Weltauffassung: Der Wiener Kreis (1929; "Scientific Conception of the
World: The Vienna Circle"), which was to be their declaration of
independence from traditional philosophy--and, in the minds of its authors
(Carnap, Hahn, and Neurath, aided by Waismann and Feigl), a "philosophy to
end all philosophies." |
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The basic ideas of Logical Positivism
were roughly as follows: the genuine task of philosophy is to clarify the meanings
of basic concepts and assertions (especially those of science)--and not to
attempt to answer unanswerable questions such as those regarding the nature of
ultimate reality or of the Absolute. Inasmuch as an extremely ambitious Hegelian
type of metaphysics, Idealistic and absolutist in orientation, was still
prevalent in the German-speaking countries, there were many who believed that
the antidote was urgently needed. Moreover, the Logical Positivists also had
only contempt and ridicule for the ideas of the German Existentialist
Martin Heidegger, whose interminable torment
regarding such questions as "Why is there anything at all?" and
"Why is what there is, the way it is?" and especially his
pronouncements about Nothingness seemed to them to be not only sterile but so
confused as to be nonsensical. The Logical Positivists viewed metaphysics
as a hopelessly futile way of trying to do what great art, and especially poetry
and music, already do so effectively and successfully. These activities, they
held, are expressions of visions, feelings, and emotions and, as such, are
perfectly legitimate as long as they make no claims to genuine cognition
or representation of reality. What Logical Positivism recommended positively, on
the other hand, was a logic and methodology of the basic assumptions and of the
validation procedures of knowledge and of evaluation. |
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An adequate understanding of the
functions of language and of the various types of meaning is another of the
fundamentally important contributions of the Logical Positivists. Communication
and language serve many diverse purposes: one is the representation of facts, or
of the regularities in nature and society; another is the conveying of imagery,
the expression and arousal of emotions; a third is the triggering, guidance, or
modification of actions. Thus, they distinguished cognitive-factual meaning from
expressive and evocative (or emotive) significance in words and sentences. It
was granted that, in most utterances of everyday life (and even of science),
these two types of meaning are combined or fused. What the Logical Positivists
insisted upon, however, was that the emotive type of expression and appeal
should not be mistaken for one having genuinely cognitive meanings. In such
expressions as moral imperatives, admonitions, and exhortations there is, of
course, a factually significant core; viz., regarding the (likely) consequences
of various actions. But the normative element--expressed by such words as
"ought," "should," "right," and their negations
(as in "Thou shalt not. . . .")--is by itself not cognitively
meaningful but has primarily emotional and motivative significance. (see also emotivism,
ethics) |
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Early statements about moral value
judgments, such as those by Carnap or by A.J. Ayer,
a more radical British Positivist, seemed shocking to many philosophers, to whom
it seemed that, in their careless formulation, moral norms were to be treated
like expressions of taste. Equally shocking was their condemnation as nonsense
(really non-sense; i.e., complete
absence of factual meaning) of all moral, aesthetic, and metaphysical
assertions. More adequate and delicate analyses, such as that of the American
Positivist Charles Stevenson, were soon to
correct and modify those extremes. By proper allocation of the cognitive and the
normative (motivative) components of value statements, many thinkers rendered
the originally harsh and implausible Positivist view of value judgments more
acceptable. Nevertheless, there is--in every Positivistic view--an ineluctable
element of basic, noncognitive commitment in the acceptance of moral, or even of
aesthetic, norms. |
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The most noteworthy, and also most
controversial, contribution of the Logical Positivists was the so-called
verifiability criterion of factual meaningfulness. In its original form, this
criterion had much in common with the earlier Pragmatist analysis of meaning (as
in Charles Sanders Peirce and William James). Schlick's rather careless
formulation: "The meaning of a [declarative sentence] is the method of its
verification," which was really intended only to exclude from the realm of
the cognitively meaningful those sentences for which it is logically
inconceivable that either supporting or refuting evidence can be found, was
close to the Pragmatist and, later, to the operationalist slogan that may be
paraphrased by: "A difference must make a difference in order to be a
difference"--or (more fully explicated): only if there is a difference in
principle, open to test by observation, between the affirmation and the denial
of a given assertion does this assertion have factual meaning. To take the
classical example from Hume's analysis of the concept of causation, there is no
difference between saying "A is
always followed by B" and saying
"A is necessarily always followed
by B." That all effects
have causes is true by virtue of the (customary) definitions of
"cause" and "effect"; it is a purely formal or logical
truth. But to say (instead of speaking of effects) that all events
have causes is to say something factual--and conceivably false. (It should
be noted that these rather crude uses of "causality" and
"necessity" were later replaced by much more subtle analyses.) (see
also verifiability principle) |
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One of the most important examples that
stimulated the formulation of the meaning criterion was Einstein's abandonment,
in 1905, of the ether hypothesis and of the
notion of absolute simultaneity. The hypothesis that there exists a universal
ether, as a medium for the propagation of light (and of electromagnetic waves
generally), had been quite plausible and was widely accepted by physicists
during the second half of the 19th century. To be sure, there were a number of
serious difficulties with the idea: the properties that had to be ascribed to
the ether were difficult to conceive in a logically compatible manner; and the
ether hypothesis in the last stage of its development (by the Dutch physicist
Hendrik Lorentz and the Irish physicist George Fitzgerald) had become
objectionable in that it sought to provide excuses for the absolute
unobservability of that mysterious, allegedly all-pervasive, universal
substance. Similarly, it had become impossible, except at the price of
intolerably ad hoc hypotheses, to maintain the notions of absolute time and of
absolute simultaneity. Thus Einstein, by eliminating these empirically
untestable assumptions, was led to his special theory of relativity. (see also special relativity) |
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Several important changes in the
formulation of the meaning criterion took place in the ensuing decades from 1930
to 1960. The original version formulated in terms of verifiability was replaced
by a more tolerant version expressed in terms of testability or confirmability.
Obviously, universal propositions, such as "All cats have claws,"
being only partially supportable by positive instances (one cannot examine every
cat that exists), are not conclusively verifiable. Nevertheless, scientists do
accept lawlike statements on the basis of only incomplete, as well as indirect,
verification--which is what "confirmation" amounts to. It was in
coming to this juncture in his critique of Positivism that Karl
Popper, an Austro-English philosopher of science, in his Logik
der Forschung (1935; The Logic
of Scientific Discovery, 1959), insisted that the meaning criterion should
be abandoned and replaced by a criterion of demarcation between empirical
(scientific) and transempirical (nonscientific, metaphysical) questions and
answers--a criterion that, according to Popper, is to be testability, or, in his
own version, falsifiability; i.e., refutability.
Popper was impressed by how easy it is to supposedly verify all sorts of
assertions--those of psychoanalytic theories seemed to him to be abhorrent
examples. But the decisive feature, as Popper saw it, should be whether it is in
principle conceivable that evidence could be cited that would refute (or
disconfirm) a given law, hypothesis, or theory. Theories are (often) bold
conjectures. It is true that scientists should be encouraged in their
construction of theories--no matter how far they deviate from the tradition; it
is also true, however, that all such conjectures should be subjected to the most
severe and searching criticism and experimental scrutiny of their truth claims.
The growth of knowledge thus proceeds through the elimination of error; i.e.,
through the refutation of hypotheses that are either logically inconsistent
or entail empirically refuted consequences. |
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Despite valuable suggestions in Popper's
philosophy of science, the Logical Positivists and Empiricists continued to
reformulate their criteria of factual meaningfulness. The Positivist Hans
Reichenbach, who emigrated from Germany to California, proposed, in his Experience
and Prediction (1938), a probabilistic conception. If hypotheses,
generalizations, and theories can be made more or less probable by whatever
evidence is available, he argued, then they are factually meaningful. In another
version of meaningfulness, first adumbrated by Schlick (under the influence of
Wittgenstein's thought), the philosopher's attention is focussed on concepts
rather than on propositions. If the concepts in terms of which theories are
formulated can be related, through chains of definitions, to concepts that are
definable ostensibly--i.e., by
pointing to or exhibiting items or aspects of direct experience--then those
theories are factually meaningful. This is the version also advocated by Richard
von Mises, an Austro-American mathematician and methodologist, in his Positivism
(1951) and, later, more technically elaborated by Carnap, in Minnesota Studies in the Philosophy of Science, vol. 1 (1956). |
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These views of meaningfulness are
essentially refinements of the doctrine of so-called protocol
sentences, developed in the late 1920s and early 1930s and elaborated
especially by Carnap, by Otto Neurath, a polymath sociologist and philosopher,
and also (with some differences) by Schlick.
Protocol sentences, originally conceived along the lines of an interpretation,
developed in the Vienna Circle, of Wittgenstein's elementary propositions, were
identified as those sentences that make statements about the data of direct
experience. But Neurath--and independently also Popper--warned of the danger
that this doctrine might lead to subjective Idealism and recommended that it be
given a rational reconstruction on an intersubjective basis. Thus, Neurath
and Carnap preferred that a physicalistic
thing-language be employed as the starting point and testing ground of all
knowledge claims. Propositions in this language would describe objectively
existing, directly observable states of affairs or events. Because all objective
and intersubjective knowledge was seen, in such a physicalism, to rest on
statements representing things and their properties, relations and ongoing
processes as they are found in unbiassed, and presumedly theory-free,
observation, the physicalists were thus proclaiming a first thesis of the
so-called Unity of Science principle. Though
Mach had proceeded from the basis of (neutral) immediate experience, his
insistence on the unity of all knowledge and all science was retained--at least
in general spirit--by the later Positivists. In this view, all classifications
of the sciences, or divisions of their subject matter, were seen as artificial,
valuable at best only administratively, but without philosophical justification. |
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Sharply to be distinguished from this
first thesis of the Unity of Science is a second that formulates a reductionism
of a very different type: whereas the first thesis concerns the unity of the
observational basis of all the sciences, the second proposes (tentatively) a
unity of the explanatory principles of science. Reductions within physics
itself, such as that of thermodynamics to the kinetic theory of heat
(statistical mechanics) and of optics to electromagnetics; and, beyond that, the
explanation of chemical phenomena, with the help of the quantum theory, in terms
of atomic and molecular processes; and, furthermore, the progress that has been
made in the physical explanation of biological phenomena (especially in the
recent development of molecular biology)--all of these encourage the idea of a
unitary set of physical premises from which the regularities of all of reality
could be derived. But it must be admitted that, in contrast to the first thesis
(which, by comparison is almost trivial), the second, being a bold conjecture
about future reductions in the sciences, might well prove to be limited in the
scope of its validity. The most controversial part of this reductionist
ideology, however, concerns the realms of organic life and especially that of
mind; it concerns, in other words, the reducibility of biology to physics and
chemistry and of psychology to neurophysiology--and (though this is clearly
utopian at present) of both ultimately to basic physics. |
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The most serious alternative to this
reducibility thesis of the Unity of Science movement is the theory of emergent
evolution, according to which life or mind
(or both) are genuinely novel forms of reality that could not possibly have been
derived from, or predicted by, any laws or theories of the lower or earlier
levels of existence. |
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Historically, it may be plausible that
the notorious perplexities of the traditional problem of how mind relates to
body motivated both the phenomenalistic Positivists as well as the Behaviourists
and physicalists. In either view, the mind-body problem conveniently disappears;
it is branded as a metaphysical pseudoproblem. The phenomenalism of Mach and the
early Russell was expressed in a position called neutral monism,
according to which both psychological and physical concepts are viewed as
logical constructions on the basis of a neutral set of data of immediate
experience. There are thus not two realities--the mental and the physical; there
are merely different ways of organizing the experiential data. In the
Behaviourist-physicalist alternative, on the other hand, the philosopher,
considering the concepts that are ordinarily taken to characterize private
mental acts and processes, defines them on the basis of publicly
(intersubjectively) observable features of the behaviour, including the
linguistic behaviour, of man. (see also mind-body dualism, behaviourism) |
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The absolute privacy of mental events
was first criticized, however, by Carnap and later by an Oxford Analytical
philosopher, Gilbert Ryle; and Wittgenstein, in
an argument against the very possibility of a private
language, maintained that, unless men have objective criteria for the
occurrence of mental states, they cannot even begin to communicate meaningfully
with each other about their direct experiences. Wittgenstein thus repudiated the
traditional view according to which a man's knowledge of other persons' minds
must be based on analogical inference from his own case. In a similar vein, an
American psychologist, B.F. Skinner, tried to
account for man's acquisition of subjective terms in his language by a theory of
verbal behaviour. A man learns to describe his mental states, explained Skinner,
from the utterances of others who ascribe these states to him by virtue of their
observation of his behaviour (e.g., in the social context; or when a certain stimulus situation
prevails in his environment). |
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Both Carnap and Ryle have emphasized
that many mental features or properties have a dispositional character.
Dispositional terms, whether used in psychology or more broadly, have to be
understood as shorthand expressions for test conditions--or test-result
conditionals. Thus, even in ordinary life, a man appraises, for example, the
intelligence of a person in the light of what he does, how he does it, how fast
he does it, when confronted with various tasks or problems. Just as such
physical properties as malleability, brittleness, or thermal or electrical
conductivity must be defined in terms of what happens when certain conditions
are imposed, so also mental dispositions are to be construed as similarly
hypothetical; i.e., as (in the
simplest case) stimulus-response relationships. |
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Logical Positivism, essentially the
doctrine of the Vienna Circle (c. 1924-38),
underwent a number of important changes and innovations in the middle third of
the century, which suggested the need for a new name. The designation Positivism
had been strongly connected with the Comte-Mach tradition of instrumentalism and
phenomenalism. The emphasis that this tradition had placed, however, on the
positive facts of observation and their negative attitude toward the atomic
theory and the existence of theoretical entities in general were no longer in
keeping with the spirit of 20th-century science. Nevertheless, the requirement
that hypotheses and theories be empirically testable, though it became more
flexible and tolerant, could not be relinquished. It was natural, then, that the
word "empiricism" should occur in any new name. Accordingly, retaining
the term "logical" in roughly its same earlier meaning, the new name
"Logical Empiricism" was coined. |
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The intention of the word "logical"
was to insist on the distinctive nature of logical and mathematical truth. In
opposition to Mill's view, according to which even logic and pure mathematics
are empirical (i.e., are justifiable
or refutable by observation), the Logical Positivists--essentially following
Frege and Russell--had already declared mathematics to be true only by virtue of
postulates and definitions. Expressed in the traditional terms used by Kant,
logic and mathematics were recognized as a priori disciplines (valid
independently of experience) precisely because their denial would amount to a
self-contradiction, and statements within these disciplines were expressed in
what Kant called analytic propositions; i.e.,
propositions that are true or false only by virtue of the meanings of the
terms they contain. In his own way, the broad-ranging scholar Gottfried
Leibniz had seen this in the 17th century long before Kant. The truth of
such a simple arithmetical proposition as, for
example, "2 + 3 = 5" is necessary, universal, a priori, and analytic
because of the very meaning of "2," "+," "3,"
"5," and "=." Experience could not possibly refute such
truths because their validity is established (as Hume said) merely by the
"relation of ideas." Even if--"miraculously"--putting two
and three objects together should on some occasion yield six objects, this would
be a fascinating feature of those objects (rabbits, perhaps); but it would not
in the least tend to refute the purely definitional truths of arithmetic. (see
also formal
logic, mathematics, philosophy of, a
priori knowledge) |
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The case of geometry
is altogether different. Geometry can be either an empirical science of natural
space or an abstract system with uninterpreted basic concepts and uninterpreted
postulates. The latter is the conception introduced in rigorous fashion by a
late 19th-century mathematician, David Hilbert,
and, still later, by a United States geometer, Oswald
Veblen. In the axiomatizations that they developed, the basic concepts,
called primitives, are implicitly defined by the postulates: thus, such concepts
as point, straight line, intersection, betweenness, and plane are related to
each other in a merely formal manner. The proof of theorems from postulates, and
with explicit definitions of derived concepts (such as of triangle, polygon,
circle, or conic section), is achieved by strict deductive inference. Very
different, however, is geometry as understood in practical life, and in the
natural sciences and technologies, in which it constitutes the science of space.
Ever since the development of the non-Euclidean geometries in the first half of
the 19th century, it has no longer been taken for granted that Euclidean
geometry is the only geometry uniquely applicable to the spatial order of
physical objects or events. In Einstein's general theory of relativity and
gravitation, in fact, a four-dimensional Riemannian geometry with variable
curvature was successfully employed, an event that amounted to a final
refutation of the Kantian contention that the truths of geometry are
"synthetic a priori." With respect to the relation of postulates to
theorems, geometry is thus analytic, like any other rigorously deductive
discipline; but the postulates themselves, when interpreted--i.e.,
when construed as statements about the structure of physical space--are
indeed synthetic, but also a posteriori; i.e.,
their adequacy depends upon the results of observation and measurement. |
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Important contributions, beginning in
the early 1930s, were made by Carnap, by Kurt Gödel, a Moravian-American
mathematical logician, and others to the logical analysis of language. Charles
Morris, a Pragmatist concerned with Linguistic Analysis, had outlined the
three dimensions of semiotics (the general study
of signs and symbolisms): syntax, semantics,
and pragmatics (the relation of signs to their
users and to the conditions of their use). Syntactical studies, concerned with
the formation and transformation rules of language (i.e., its purely structural features), soon required supplementation
by semantical studies, concerned with rules of designation and of truth.
Semantics, in the strictly formalized sense, owed its origin to Alfred
Tarski, a leading member of the Polish school of logicians, and was then
developed by Carnap and applied to problems of meaning and necessity. As
Wittgenstein had already shown, the necessary truth of tautologies
simply amounts to their being true under all conceivable circumstances. Thus the
so-called eternal verity of the principles of identity (p
is equivalent with itself), of noncontradiction (one cannot both assert and
deny the same proposition), and the principle of excluded middle (any given
proposition is either true or false; there is no further possibility) is an
obvious consequence of the rules according to which the philosopher uses (or
decides to use) the words "proposition," "negation,"
"equivalence," "conjunction," "disjunction," and
others. Quite generally, questions regarding the meanings of words or symbols
are answered most illuminatingly by stating the syntactical and the semantical
rules according to which they are used. (see also Analytic philosophy) |
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Two different schools of thought
originated from this basic insight: (1) the philosophy of "ordinary
language" Analysis--initiated by Wittgenstein,
especially in his later work, and (following him) developed in differing
directions in the works of Gilbert Ryle and John
Langshaw Austin, both Oxford philosophers, of the Cambridge Analyst John Wisdom,
and others; and (2) the ideology, essentially that of Carnap, usually designated
as logical reconstruction, which builds up an artificial language. In the
procedures of "ordinary language" Analysis, an attempt is made to
trace the ways in which a person commonly expresses himself. In this manner,
many of the traditional vexatious philosophical puzzles and perplexities are
shown to arise out of deviant uses of language. (Lewis Carroll had already
anticipated some of these oddities in his whimsical manner in Alice
in Wonderland.) The much more rigorous procedures of the second school--of
Tarski, Carnap, and many other logicians--rest upon the obvious distinction
between the language (and all of its various symbols) that is the object of
analysis, called the object language, and that
in which the analysis is formulated, called the metalanguage.
If needed and fruitful, this process can be repeated, in that the erstwhile
metalanguage can become the object of a metametalanguage, and so on--without the
danger of a vicious infinite regress. (see also ideal
language) |
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With the help of semantical concepts, an
old perplexity in the theory of knowledge can then be resolved. Positivists have
often tended to conflate the truth conditions of a statement with its confirming
evidence, a procedure which has led to certain absurdities committed by
phenomenalists and operationalists, such as the pronouncement that the meanings
of statements about past events consist in their (forthcoming future) evidence.
Clearly, the objects--the targets or referents--of such statements are the past
events. Thus the meaning of a historical statement is its truth conditions; i.e.,
the situation that would have to obtain if the historical statement is to be
true. The confirmatory evidence, however, may be discovered either in the
present or in the future. Similarly, the evidence for an existential hypothesis
in the sciences may consist, for example, in cloud-chamber tracks, spectral
lines, or the like, whereas the truth conditions may relate to subatomic
processes or to astrophysical facts. Or, to take an example from depth
psychology, the occurrences of unconscious wishes or conflicts are the truth
conditions for which the observable symptoms (Freudian lapses, manifest dream
contents, and the like) serve merely as indicators or clues; i.e., as items of confirming evidence. |
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The third dimension of language (in
Morris' view of semiotic)--i.e., the
pragmatic aspect--has not been as fully and formally analyzed as the other two
dimensions. There is even some disagreement as to whether some of the cognitive
activities (such as verifying, refuting, or interpreting), in addition to the
noncognitive functions (such as the motivative and persuasive appeals), are to
be included in studies of pragmatics. |
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One of the most surprising and
revolutionary offshoots of the metalinguistic (formal) analyses was Kurt
Gödel's discovery, in 1931, of an exact proof of the undecidability
of certain types of mathematical problems, a discovery that dealt a severe blow
to the expectations of the Formalistic school of mathematics championed by
Hilbert and his collaborator, Paul Bernays. Before Gödel's discovery, it
had seemed plausible that a mathematical system could be complete in the sense
that any well-formed formula of the system could be either proved or disproved
on the basis of the given set of postulates. But Gödel showed rigorously
(what had been only a conjecture on the part of the Dutch Intuitionist L.E.J.
Brouwer and his followers) that, for a large class of important mathematical
systems, such completeness cannot be achieved. (see also Gödel's
first incompleteness theorem) |
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Both Carnap and Reichenbach, in their
very different ways, made extensive contributions to the theory of probability
and induction. Impressed with the need for an interpretation of the concept of
probability that was thoroughly empirical, Reichenbach elaborated a view that
conceived probability as a limit of relative frequency and buttressed it with a
pragmatic justification of inductive inference. Carnap
granted the importance of this concept (especially in modern physical theories)
but attempted, in increasingly refined and often revised forms, to define a
concept of degree-of-confirmation that was purely logical. Statements ascribing
an inductive probability to a hypothesis are, in Carnap's view, analytic,
because they merely formulate the strength of the support bestowed upon a
hypothesis by a given body of evidence. |
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Logical Positivism and Logical
Empiricism have from their very beginnings been subjected to searching
criticisms. At first it was the verifiability criterion of meaningfulness that
produced a storm of oppositions. One group of critics asked whether the
criterion was meaningful in the light of its own standard. Carnap replied that
the criterion itself was not intended as a factual assertion but rather as a
proposal for a better and clearer use of language. Nevertheless, the Logical
Empiricists felt that the (tolerant-liberal) formulation of the meaning
criterion--far from being an arbitrary injunction--came rather close to what
enlightened common sense, and especially the scientific attitude, intended by
the difference between sense and non-sense. |
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Other recent and current criticisms
concern the Logical Empiricist views regarding the nature of scientific
explanation, in regard to which matters are not as simple as they were
originally conceived to be. Closer attention to the history of scientific
theories has revealed important discontinuities, or revolutions, in the
conceptual schemes of the sciences. The significant role of statistical (or
probabilistic) explanations in most modern sciences, for example, is receiving
increasingly sophisticated analyses. |
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Nevertheless, the prevalence of
scientific revolutions and anarchism or subjectivism in scientific method has
been exaggerated in differing ways by several scholars. As has been conceded by
all competent philosophers of science and even by the greatest
scientist-philosophers of the century -- Albert
Einstein, Niels Bohr, Erwin Schrödinger, and others--there is no
straight logical path, no standard recipe, by which to move from the data of
observation and arrive at scientific theories. It may also be admitted that,
though scientific creativity has psychologically much in common with artistic
creation, the criteria of appraisal are certainly quite different. And,
although, from the present critical point of view, all and any scientific
assertions are in principle subject to revision, it is nonetheless felt to be
grotesque to deny the relative stability of the empirical laws that serve as the
testing ground of alternative theories. |
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(H.Fe.) |
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