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The discipline here
entitled "the philosophy of
nature" consists in the investigation of substantive issues
regarding the actual features of nature as a reality and is divided into two
parts: the philosophy of physics
and the philosophy of biology. In this discipline, the most fundamental, broad,
and seminal features of natural reality as such are explored and assessments are
made of their implications for man's metaphysics, or theory of reality;
for his Weltanschauung, or "world view"; for his anthropology,
or doctrine of man; and for his ethics, or theory and manner of moral action.
These implications are explored on the assumption that man's understanding of
the natural setting in which his life is staged strongly conditions his beliefs
and attitudes in many fields. (see also biological
productivity) |
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In its German form,
Naturphilosophie, the term is chiefly identified with Friedrich
Schelling and G.W.F. Hegel,
early 19th-century German Idealists who opposed it to Logik and to the Ph?omenologie
des Geistes ("of the spirit or mind"). Employment of the term
spread, in due time, beyond its narrower historical context in German Idealism
and came to be used, particularly in Roman Catholic parlance, in the sense that
it bears in this article (e.g., the philosophies of physics and biology).
Despite a notable decline in its usage in more recent years, the term is here
employed, in the interest of the clear delineation of topics, as a complement to
the philosophy of science, the discipline to which its subject matter has been
allocated by recent philosophers. Thus in this work, the article on the
philosophy of science is largely restricted to man's approach to nature, and
thus to epistemological (theory of knowledge) and methodological issues, while
that on the philosophy of nature encompasses the more substantive issues about
nature as it is in itself. |
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3.1.1.1
Physics as a field of inquiry.
3.1.1.1.1
Essential
features.
Physics is
concerned with the simplest inorganic objects and processes in nature and with
the measurement and mathematical description of them. Inasmuch as the binding
forces of chemistry can now,
at least in principle, be reduced to the well-known laws of physics, or
calculated from quantum mechanics (the theory that all energy is radiated or
absorbed in small unitary packets), chemistry can henceforth be considered as a
part of physics in theory if not in practice. Moreover, it has become clear,
through the general theory of relativity
(which formulates nature's laws as viewed from various accelerating
perspectives), that there is an aspect of geometry, too, that can be regarded as a part of physics. The
fact that, over a wide range of circumstances, Euclidean, or ordinary uncurved,
geometry presents a good approximation to reality is considered today not as a
fact stipulated by a necessity of thought, nor a derivative from such a
necessity, but as a fact to be established empirically; i.e., by
observation. In their application, the laws of Euclidean
geometry refer to those experiences that arise with measurements of
length and angle and optical sightings as well as with surface and volume
measurements. The possibility--already extensively elucidated in antiquity--of
deriving geometrical propositions by deduction from a few axioms, assumed
without proof to be correct, had given rise in earlier philosophy to the opinion
that the truth of these axioms
must and could be guaranteed by a kind of knowledge that is independent of experience. The recognition of
such a priori knowledge,
however, has been superseded by the modern development of physics. While it is
granted that a pure geometry is free to posit any axioms that it pleases, a
geometry purporting to describe the real world must have true axioms. Today it
is considered that, if Euclidean geometry is true of the world, this truth must
be established empirically; the axioms would be true because the conclusions
drawn from them correspond to experience. Actually, the world appears Euclidean,
however, only when this experience is limited to cases in which the distances
are not too great (not much greater than 109 light-years) and in
which gravitational fields
are not too strong (as they are in the vicinity of a neutron star). |
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The possibility of
deducing all known laws or regularities as logical inferences from a few axioms,
which was discovered in Euclidean geometry, became a model for the construction
also of another chapter in the history of physics. The classical physics of
Newton, the 17th-18th-century father of modern physics, had employed Euclidean
geometry as a foundation and had portrayed the solar system as a system of mass
points subject to his mechanical axioms. The laws for falling bodies framed by
the 16th-17th-century Italian physicist Galileo are the simplest logical
consequences of Newton's axioms, and the laws framed by Johannes Kepler, a
16th-17th-century German astronomer,
which precisely describe the motions of the planets, follow from them. |
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In addition to the
laws of mechanics there are those of the broad sphere of electromagnetic
phenomena as summarized in the equations of James Clerk Maxwell, a 19th-century
Scottish physicist, which describe both the electric and magnetic fields and the
laws of their mutual changes, equations that may thus be considered as the
axioms of electrodynamics.
Because they assume the mathematical form of partial differential
equations--which express the rates at which differentials (small or
infinitesimal distances or quantities) in several dimensions change with respect
to their neighbours--electrodynamics is a local-action
theory rather than an action-at-a-distance
theory as in older formulations modelled after Newton's law of
gravitation. The principle of local action states that the variations of
electromagnetic magnitudes at a point in space can be influenced only by the
electromagnetic conditions in the immediate vicinity of this point. The finite
velocity of propagation for electromagnetic disturbances, which follows from
this principle, leads on the one hand to the existence of electromagnetic wave
events and on the other hand to conformity with the requirements of special
relativity (a theory that formulates nature's laws as viewed from the
perspectives of various velocities), which demand a maximum finite velocity for
signals--the velocity of light in a vacuum. (see also Maxwell's
equations)
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The most important
division of physics today is one that replaces the traditional distinctions
between mechanics, acoustics, and other classical branches of physics with that
between macroscopic and microscopic physics, in which the latter investigates
the conformity of atoms to law and their reactions in discrete quantum jumps,
whereas the former extends from the level of ordinary human experience into
astronomy to a total comprehension of the universe, attained through theoretical
endeavours in the field of cosmology.
Because it is now possible to observe especially bright objects (quasars) that
are located perhaps 1010 light-years from the Earth, the possibility
of empirically testing cosmological models is beginning to arise. In particular,
the application of non-Euclidean, or curved, geometries to the cosmos has
suggested the conception of a finite, yet boundless, world space (positively
curved), in which the maximum possible distance between two points would no
longer be much greater than 1010 light-years. |
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In the historical
development of physics before the 17th century, geometry was the only field in
which extensive advances were made; besides geometry, only the rudiments of
statics (the laws of levers, the principle of hydrostatics of the 3rd-century BC
scientist Archimedes) were clarified. After Galileo had discovered the laws of
falling bodies, Kepler's laws describing the motions of the planets and Newton's
reduction of them to a set of dynamical axioms established the science of classical
mechanics, to which was annexed the investigation of
electromagnetism. These developments culminated in the discovery of induction by
Michael Faraday, an English physical scientist, the knowledge of local action by
Faraday and Maxwell, and the discovery of electromagnetic waves by a German
physicist, Heinrich Hertz. It was not until the 19th century that the law of the
conservation of energy was
first recognized as a general law of nature, through the work of Julius
von Mayer in Germany and James
Joule in England, and that the concept of entropy (see below Problems
at the macrophysical level )
was formulated by Rudolf Clausius,
a mathematical physicist. At the beginning of the 20th century, the German
physicist Max Planck
introduced the so-called quantum of action, h = 6.626 ?10-27
erg-seconds, which, when multiplied by the vibration frequency, symbolized by
the Greek letter nu,
 ,
demarcates a basic packet of energy. Albert Einstein then extended the quantum theory to light. The real existence of atoms was proved
by him and other investigators, and the science of microphysics thus arose. The
researches of Niels Bohr on the quantum-theoretical significance of atomic
spectra paved the way for broader search into the fine details of quantum laws,
the final comprehension of which was introduced by Werner Heisenberg in 1924 and
then systematically developed by Max Born, Heisenberg, and Pascual Jordan, of
Germany, and by P.A.M. Dirac, of England. Moreover, Erwin
Schr?inger, an Austrian physicist, pursuing a line of thought pointed
out by Einstein and Louis de Broglie, arrived at results that were outwardly
quite different from those of Heisenberg et al., but were mathematically
equivalent. The quantum mechanics, or wave mechanics, created by these men,
which formulated quantum phenomena, were later extended to quantum
electrodynamics. (see also Planck's
constant) |
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Einstein's theory
of relativity, first formulated in 1905, which was eventually extended from a
special to a general formulation, brought about a revolutionary transformation
in physics similar to that induced by quantum theory. The Newtonian mechanics of
mass points turned out to have been merely an approximation to the more exact
relativistic mechanics. The most important consequence of the special theory of
relativity, the equivalence of mass (m) and energy (E), |
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in which c is
the velocity of light, was formulated by Einstein himself. |
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After 1916 Einstein
strove to extend the theory of relativity to the so-called general theory, a
formulation that includes gravitation, which was still being expressed in the
form imparted to it by Newton; i.e., that of a theory of action at a
distance. Einstein did succeed in the case of gravitation in reducing it to a
local-action theory, but, in so doing, he increased the mathematical complexity
considerably, as Maxwell, too, had done when he transformed electrodynamics from
a theory of action at a distance to a local-action theory. |
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The great
importance of physics for the technology that depends upon it--which has become
a leading factor in the rapidly increasing development in the conditions of
human existence--is shown historically in the close connection of decisive
technical developments with basic advances in physical knowledge. Einstein's
equivalence of mass and energy--to cite but one example--pointed to the atomic
nucleus as an energy source that could be opened up through the study of nuclear
physics. Moreover, the intellectual influence proceeding from physics and
affecting the development of modern thought has become especially strong through
the deepened grasp of the concept of causality that has followed from quantum
theory (see below Modalities of
the natural order ). (see
also nuclear energy) |
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3.1.1.2.1
Framework
of the natural order.
Earlier
mathematicians and particularly Richard
Dedekind, a pre-World War I number theorist, have precisely defined
the concept of real numbers,
which include both rational numbers, such as 277/931, expressible as ratios of
any two whole numbers (integers), and irrational numbers, such as {radical} 27,
 , or e,
which lie between the rationals. By reference to these numbers, the
Newtonian concept of space and time, which presupposes a Euclidean geometry of
space, may be made precise: the values of the time t, ordered according
to the ideas of earlier and later, can be made to correspond to the single real
numbers, ordered according to those of smaller and larger. Also, the points on a
straight line can be brought into correspondence with the real numbers in such a
manner that the location of a point P between two other points P1
and P2 corresponds to a number assigned to P that lies
between those assigned to P1 and P2. |
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Guided by the wish
to find a method that allows the systematic proof of all philosophical truths, Ren?Descartes,
often called the founder of modern philosophy, established in the 17th century
the analytic geometry of Euclidean planes. In it the points of a plane can be
designated by two numbers x, y, their coordinates. One chooses two
orthogonal coordinate axes, x = 0 and y = 0, like those of a
graph, and, with any point P, associates its two projections, one upon
each coordinate axis, which define the location of P. A curve in the x
- y plane is then expressed by an equation f (x,y) = 0,
shorthand for any equation ("function") containing x's and y's.
In the context of analytic geometry,
every theorem of plane Euclidean geometry may be expressed by equations and thus
be analytically proved. |
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This procedure can
also be extended to three-dimensional Euclidean space by introducing three
mutually perpendicular axes x,y,z. In this case, there are two different
axis systems--either congruent or mirror reflections--analogous to right-handed
and left-handed screws. |
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The simple
space-time relationships of Newtonian physics have been changed in many ways by
modern developments. The concept of simultaneity
has been made relative by the special theory of relativity; every time
measurement t is thus tied to a definite inertial system or moving frame
of reference. It is accordingly appropriate to speak not primarily of points in
time but of events, which are defined in each case by giving both a point in
space and a point in time. |
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More specifically,
an inertial system is a
coordinate system that, relative to the fixed stars, is in uniform,
straight-line motion (or at rest) with no rotation. In all inertial systems,
Newton's principle of inertia, which states that all mass points not acted upon
by some force persist in uniform motion with a constant velocity, is valid. |
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Moreover,
cosmological theories make it probable that space in the real astronomical
universe corresponds only approximately to the relationships of Euclidean
geometry and that the approximation can be improved by replacing Euclidean space
with a space of constant positive curvature. Such a space can be mathematically
defined as a three-dimensional hyperspherical "surface" |
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in a hypothetical
Euclidean space of four dimensions with mutually perpendicular x,y,z, and
u coordinate axes. |
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The assertion that
the foregoing statement has no operationally comprehensible content--i.e., no
content provable by performable measurements--is designated conventionalism,
a view that is based on a remark by a French mathematician, Henri
Poincar, who was also a philosopher of science, that a fixed
non-Euclidean space can be mapped point by point on a Euclidean space so that
both are suitable for the description of the astronomical reality. The range of
this remark is limited, however, in that this mapping, though it can indeed
carry over points into points, can in no way carry over straight lines into
straight lines. Hence, many philosophers of science have held that, as long as
astronomical light rays are held to be straight lines, the question of a
possible curvature of space (i.e., a deviation from Euclidean conditions)
will by no means be solved by some arbitrary convention; that it signifies,
instead, a problem to be solved empirically. If the universe in fact has a
positive constant curvature, then every straight line has a length that is only
finite, and its points no longer correspond, as in the Euclidean case, to the
set of all real numbers. |
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In a very definite
manner, cosmological facts have further indicated that time
is by no means unlimited both forward and backward. Rather, it seems that time
as such had a beginning about 1010 to 2 ?010 years ago;
thus, with an explosive beginning, the cosmic development began as an expansion.
(see also big-bang model) |
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The foregoing
discussion has considered only the replacement of Euclidean spatial concepts by
an elementary non-Euclidean geometry corresponding to a space with a constant
curvature. According to Einstein,
however, the fundamental idea of a still more generalized Riemannian
geometry, so-called after Bernhard Riemann, a geometer and function
theorist, must be brought into play in order to produce a local-action theory of
gravitation. |
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Riemannian geometry
is a further development of the theory of surfaces created by the 18th- and
19th-century German mathematician and astronomer Carl
Friedrich Gauss, often called the founder of modern mathematics, a
theory that aimed to investigate the curved surfaces of three-dimensional
(Euclidean) spaces with exclusive regard to their own inner dimensions and no
consideration of their being imbedded in a three-dimensional space. (see also Gaussian
curvature) |
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Gauss thought that
the points on such a surface could be specified by reference to two arbitrary
coordinates u and v defined with the help of two single-parameter
families of curves, u = constant and v = constant. The square of
the infinitesimal distance between two adjacent points of the surface, ds2,
is then a quadratic form of the differentials du and dv, belonging
to the pair of points, namely, |
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in which the
coefficients gk1 are functions of position. One can
then calculate the curvature corresponding to the location of the pair of points
according to a prescription given by Gauss, a curvature that measures the
deviation from Euclidean plane behaviour that exists at this point. The
curvature is a definite function of the gk1 and their
first derivatives. |
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Riemann extended
Gauss's considerations to the case of a three-dimensional space that can have
different curvature properties from place to place (expressed by several
functions of position that are collectively called the curvature tensor); and
Einstein generalized these ideas still further, applying them to the
four-dimensional space-time continuum, and thereby attained a reduction of the
Newtonian action-at-a-distance theory of gravitation to a local-action theory.
(see also non-Euclidean geometry,
Riemann-Christoffel curvature tensor)
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Among the most
basic constituents of the physical world are symmetries, fields, matter, and
action. |
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Symmetry
is one of the chief concepts of modern mathematics, which combines the different
symmetries belonging to an object or a concept into groups
of relevant symmetries. The a priori investigation of the totality of possible
groups, defined with respect to some operation (such as multiplication),
comprises a division of modern mathematics called group theory. |
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Three-dimensional Euclidean
space displays several important symmetry properties. It is
homogeneous; i.e., arbitrary shifts in the origin or zero point of the
coordinate system produce no change in the analytic expression of the
geometrical laws. It is also isotropic; that is, rotations of the coordinate
system leave all geometrical laws in effect. Further, it is symmetric with
regard to mirror reflections. It is tempting to suppose that these symmetry
properties of space are also valid for the physical processes that occur in
space, and this is indeed true over a wide range of cases, but not in all cases
(for exceptions, see below Problems
at the quantum level ). |
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That Newtonian
mechanics and Maxwellian electrodynamics display in fact all of the symmetries
of Euclidean space is revealed by the fact that they can be formulated in the
language of vector analysis.
Passing over the more familiar Newtonian mechanics, a few points about Maxwell's
theory may be mentioned. This theory can be made to satisfy the requirements of
operational thinking by ascribing to the electric and magnetic field strengths
the significance of measurable physical realities, which makes it unnecessary to
interpret them as states of a mysterious, hypothetical substance or ether, for
which, in any case, the special theory of relativity (with the equivalence of
all inertial systems) has no place. |
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Mathematically
interpreted, a vector a represents a quantity with both magnitude and
direction, which preserves its length or value and its direction when displaced.
The vector field--i.e., the
association of a vector with every point in space (e.g., electric field
strength, or electric current density)--and the line
integral (or summation) of a vector field V along a curve K
leading from a point P to a point P ' are basic concepts in vector
analysis. To obtain the line integral, the curve K is divided into
infinitesimal elements ds, the scalar (numerical or nonvector) product of
ds with the value of V at that point is taken, and the results are
summed with an integration. |
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A small surface
area envisioned with a given sense of rotation around its boundary curve can
also be described by a vector. In this instance, the vector, dF is
perpendicular to the surface and forms, with the sense of rotation about the
boundary, a right-handed system. Its magnitude is the area of the surface. The
flux of the vector field V through the surface dF is called the
scalar product V ?dF. |
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If V has the
property that the line integral along every closed curve K is equal to
zero, then V is said to be irrotational. This property is equivalent to
the requirement that the vector field be a so-called gradient
field; i.e., that there exist a scalar field quantity W with the
property that the difference in the value of W at two points P and
P ' is equal to the line integral of the vector field V from P to
P ' (along any arbitrary curve K ). If V is, for example,
an electrostatic (charged) field, the significance of being irrotational is that
one can gain no mechanical work in leading a small test charge around any closed
curve; the work involved is
equal to zero. For an unclosed curve K, however, the movement of the test
charge yields an amount of mechanical work that is proportional to the potential
difference between the endpoints of the curve. The components of the gradient of
W, expressed in partial derivatives
 ,
are |
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If the vector field
is not irrotational, there can then be constructed from it an adjunct rotational
field, called curl V, by considering a small (infinitesimal) surface area
dF located at a point P and forming the line integral of V along
the boundary curve of dF. Then, when this line integral is divided by the
magnitude of the surface area, the component of the curl V parallel to
the vector dF is obtained. |
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On the other hand,
the flux of a vector field V
out of a closed surface can be formed by integration. If this flux is always
zero (for every choice of a closed surface), V is called source-free.
Otherwise, there is a so-called divergence of V at a point P, which
is defined as follows: one divides the net flux of V out of a small
surface that surrounds P by the volume enclosed by the surface. The limit
of this quotient for infinitesimally small surfaces is called the divergence of V
at P or the source field div V. (see also divergence
of a vector field) |
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The formulation of
the basic laws of electrodynamics given by Maxwell is called the Maxwell
equations. These equations contain, for example, the statement that,
in a vacuum, the source field of the electric field strength is proportional to
the spatial electric charge density, symbolized by the Greek letter rho,
 , and
that the magnetic field
strength is source-free (divergence equal to zero). Thus, magnetic monopoles
having no correlate of opposite sign do not exist. Remembering that every
source-free vector field may be expressed mathematically as a rotation field
(and vice versa), it is possible to derive the magnetic field strength H as
a rotation field from a vector field A, which is usually called the
vector potential of H |
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The fundamental law
of the conservation of charge results from Maxwell's equations in the form of
the continuity equation (see also charge
conservation) |
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in which
is
the time derivative of the charge density, and the vector field i is the
electric current density. |
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In the case of a
vacuum, the Maxwell equation that expresses Faraday's
law of induction takes the form of a proportionality between the
rotation field of the electric field strength and the time derivative of the
magnetic field strength: |
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It is a significant
fact that Maxwell's theory leads to a localization of energy,
which in electromagnetic fields is propagated somewhat in the manner of a
substance, with a density that, for the vacuum case, is |
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There remains also
the unsolved problem of clarifying the relation of gravitation to quantum
theory, which is much aggravated by the fact that gravitational energy allows of
no similar localization. |
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In both mechanics
and electrodynamics, the fundamental equations have such a form that they can be
understood as the conditions for a variational or an extremal principle: that,
through the fulfillment of these conditions, a certain integral receives an
extreme value. This integral, which has the dimensions of action--i.e.,
of energy times time--is one of the most fundamental quantities of nature.
Although the concept of action is less obvious to man's physical intuition than
that of energy, it is of even greater significance, as it appears also in
connection with the quantum laws. For the basic constant of all of quantum
physics, which always occurs in the laws of this domain, is likewise of this
dimension: namely, Planck's quantum of action (see also Planck's
constant) |
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In a purely phenomenalist
theory of matter--i.e., a
theory that does not go into the details of atomic physics but considers matter
only in a first approximation as a spatially extended continuum--numerous
material properties are ascribed to every type of matter, properties such as
density, electrical conductivity, magnetizability, dielectric constant, thermal
conductivity, and specific heat. To be complete, a theory must provide a means
of deriving all of these material properties theoretically from the laws of
atomic physics. |
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The hiatus-free causality
envisioned throughout the science of physics before the rise of quantum theory
cannot be separated conceptually from the far-reaching assumption that all
physical processes are continuous. It had been supposed that continuous changes
in antecedent causal processes would issue in continuous changes in the sequence
of processes that are causally dependent upon them. Quantum
physics, however, has expressly breached the old philosophical axiom that natura
non facit saltus ("nature does not make leaps") and has introduced
a granularity not only in the matter filling space but also in the finest
processes of nature. It is therefore only logical that, with respect to
causality, the quantum theory would arrive at new and modified ideas as well.
Renouncing unbroken causality, it speaks only of a probability
that is statistical and a predetermination for the discrete saltatory events of
which physical processes consist--a view that must now, in spite of Einstein, be
regarded as irrevocable. |
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The special theory
of relativity demands that the fundamental validity of the local-action
principle be acknowledged: all actions have only finite velocities of
propagation, which cannot exceed the velocity of light. Thus, in relativistic
cosmology it is quite possible that two partial regions of the total spatial
manifold may exist between which no causal interaction can occur: causal
influences could then assert themselves only inside the so-called interdependent
regions in the space-time manifold. These remarks also apply to the quantum
theory, in which, however, instead of a causal dependence of physical processes
upon each other, there is only an induction of statistical probabilities for
possible quantum transitions. (see also special
relativity) |
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Moving in quite
different directions, the theory of relativity on the one hand and the quantum
theory on the other have diverged from the earlier ideas of classical physics,
which were considered unalterable. There are some physical problems, however,
that can be thought through only by appealing to both the relativistic and the
quantum-theoretical modifications. A so-called joint relativistic and
quantum-mechanical theory suitable for such problems is quantum
electrodynamics, the development of which, however, is not yet
complete. Its development was greatly hindered at first by certain mathematical
difficulties (so-called divergences), which it later became possible to mitigate
by renormalization--i.e.,
by a technique of correcting the calculated results. The more generally
conceived quantum theory of wave fields finds a broad area of possible
application in the physics of the different kinds of elementary, though
short-lived, particles produced by the huge high-energy accelerators. In its
final form, the theory of elementary
particles should not only formulate, in general, the laws valid for
all known elementary particles
but should also allow a deductive derivation for all possible kinds of
elementary particles--analogous to the derivations of elements in the periodic
table. Heisenberg endeavoured to set up this far-reaching problem, which has
been called the world formula, for a solution. Imposing mathematical
difficulties, however, have arisen in the attempt to clarify its consequences
for a quantitative comparison with experience, and considerable further work may
still be required. |
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3.1.1.3.1
Problems
at the formal level.
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Euclidean
space, in contrast to imaginable spatial structures that deviate from it, is
distinguished by the simplicity of the topological properties (those preserved
through rubberlike stretching and compressing, but without any tearing) that
arise from its unusually simple continuity relationships. One may ask, then,
whether the empirical knowledge of modern physics gives any cause to consider
deviations from the topological relations of Euclidean space. The American
physicist John A. Wheeler,
author of a new theory of physics called geometrodynamics, has speculated about
this question. In particular, he has pointed to the possibility of so-called worm
holes in space, analogous to the way in which the cylindrical surface of a
smooth tree trunk is changed topologically if a worm bores a hole into the trunk
and emerges from it again elsewhere: the surface of the trunk has thus obtained
a "handle." Similarly, one can envision certain handles being added to
three-dimensional Euclidean space. Whether this hypothesis can be fruitful for
the theory of elementary particles is yet to be determined. From the
methodological and epistemological standpoints, it is obvious that a geometrical
structure is here being assumed, the measurement of which is fundamentally
hindered by the lack of rulers with calibrations smaller than the structure
itself. Presumably, the practical possibility of appealing to such topological
modifications of the ordinary notion of space is to be found in astrophysics
rather than in elementary particle physics. Viktor
A. Ambartsumian, an Armenian-born astrophysicist, is convinced that
the processes involved in the origins of galaxies are connected with explosions
in which the matter of new stellar systems arises from prestellar material; it
has been found tempting to suppose that this prestellar material exists in
regions with unusual topological properties.
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The basic idea of
the special theory of relativity can also be understood as a statement about the
symmetry properties of the four-dimensional
space-time manifold. The special principle of relativity states, in
fact, that the same physical laws are valid in all of the various inertial
coordinate systems--in particular the law that the velocity of light in a vacuum
always has the value c. This equivalence of the space-time coordinates x,y,z,t
with other coordinates x', y', z', t' that are
linear, homogeneous functions of the unprimed coordinates can be expressed by
the equation (see also special
relativity) |
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In this
formulation, the isotropy of space--its sameness in all directions--appears as a
special case of a more comprehensive symmetry property of the space-time
manifold. When t = t', the special case of a purely spatial
rotation of coordinates is obtained; and in the general case, in which the
primed coordinates are moving with velocity u with respect to the
unprimed, the famous Lorentz
transformations are obtained, which, to adjust to the finiteness of c,
add a factor, symbolized by the Greek letter gamma,
 to the ordinary
Galilean transformation,
 thus yielding |
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The group of
symmetries of the four-dimensional space-time manifold thus produced is called Poincar?group.
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Problems of
particle theory, complementarity, and symmetry have arisen in studies at the
quantum level. |
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Whereas the atomic
nuclei beyond hydrogen-1 (the proton) are compounded structures, consisting of
neutrons and protons, modern physics also deals with numerous elementary
particles--neutrinos;
(pi),
 (mu), and
K mesons; hyperons; etc.--that are thought of as uncompounded. The elementary
particles of each particular kind show no individual differences. Each
elementary particle has a corresponding antiparticle,
which, for charged particles, always carries a charge of opposite sign. (The
 [photon],
0,
and Z0 particles are understood to be their own
antiparticles.) Whether Heisenberg's
world formula can provide a complete framework for all possible kinds of
elementary particles is undecided. |
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Every type of
elementary particle has a definite value for its spin,
either integral (e.g., photons) or half-integral (e.g., electrons,
protons, neutrinos). Particles with half-integral spin obey Fermi-Dirac
statistics; those with integral spin obey Bose-Einstein
statistics, which differ in form as u/(1 + u) differs
from u/(1 - u)--u being any function. The conformity to law
that underlies the Fermi-Dirac statistics for electrons was first recognized by Wolfgang
Pauli and formulated as the Pauli
exclusion principle, which played a decisive role in settling upon
the shell structure in the periodic system of the elements. |
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The basic duality
of waves and corpuscles is of universal significance for all kinds of elementary
particles, even for composite particles in those experiments that cannot lead to
a breakup of the particles into their component parts. (see also uncertainty
principle, wave-particle
duality) |
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An electron
(and analogously any other elementary particle or even, for example, an alpha
particle) can appear just as well in the form of a wave as in that of a
localized corpuscle. In an idealized thought experiment, one can imagine that
the position of an electron can be ascertained with a gamma-ray microscope. If
the electron is described in terms of wave processes in the sense of Schr?inger's
wave mechanics, a very sharply concentrated wave packet appears at
the stated position. In an investigation of this packet by Fourier
analysis--a technique that analyzes a function into its sinusoidal
components--wave components of quite different wavelengths occur; thus an
electron in this condition has no definite value for its de Broglie wavelength
and consequently none also for its translational momentum.
Then, as stated in the so-called de Broglie relation, (see also de
Broglie wave) |
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there is for an
electron moving free from impinging forces a corresponding wavelength,
symbolized by the Greek letter lambda,
 , that
is inversely proportional to its momentum mv. And conversely, an electron
moving inertially with a definite momentum (which in the limiting case of small
velocities is equal to the product of the mass and the velocity vector) has no
definite position. If an electron that is moving inertially (especially an
electron at rest) is constrained by the use of a gamma-ray microscope to
"make up its mind," as it were, on a location, then the probability of
its appearance at a point in space is the same for all locations. More precisely
stated, the probability of the appearance of the electron in a definite volume
is proportional to the magnitude of this volume. |
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In particular, it
will be helpful to consider an electron moving in the x-direction and to
suppose that it has a wave amplitude that depends only upon x, an
electron in which the most representative wavelengths are confined to a narrow
interval while the amplitudes that are discernibly different from zero are
likewise confined to a certain interval
 x. If,
on the other hand,
p is
the range of discernible momentum values--computed from the discernible
wavelengths that represent them according to the de Broglie relation (12)--then
the product of the uncertainties
x and
p cannot
be smaller than Planck's fundamental quantum of action h. This statement
comprises the famous Heisenberg uncertainty relation, which expresses the
"complementarity" of position and momentum--as Niels Bohr
characterized it. (see also Planck's
constant) |
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If one assumes, as
above, that all physically possible states of an electron can be represented by
Schr?inger's wave mechanics, then the complementarity of the position coordinate
x and its corresponding conjugate momentum px is a
simple mathematical fact. When one thinks primarily of physical-measurement
experiments, it should be emphasized that stringent limitations are imposed on
the simultaneous measurement of the position and momentum of a particle which,
according to the uncertainty principle, make it impossible to measure
simultaneously both of these complementary quantities with unlimited precision.
In an experiment that measures its position, the electron is forced into a
sharper localization; and its particle nature is evident. By contrast, in an
experiment that measures its momentum, an interference experiment is involved;
the electron must be able to display a certain wavelength, which requires an
adequately extended region in space for its reacting. These two complementary
and opposing demands can be brought into harmony only in the sense of a
compromise; and the Heisenberg uncertainty relation formulates the best possible
compromise. (see also complementarity
principle) |
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Thus, it becomes at
the same time clear that the state of the electron given in the wave-mechanical
description before carrying out a new measurement experiment can establish only
a statistical prediction for the result. The probability density for the
appearance of an electron at a point in space is given by the square of the
absolute value of the (complex) Schr?inger wave amplitude; for a definite result
in measuring a wavelength or a momentum, the square of the absolute value of the
(complex) Fourier coefficient belonging to it provides the standard. The general
statistical transformation theory of quantum mechanics (as
developed by Dirac and Jordan) gives a complete review of the measurable
physical quantities for a microscopic mass point (or a system of such points).
According to this theory, two different measurable quantities A and B can
be simultaneously determined with unlimited precision only if the operators or
matrices that describe A and B commute--i.e., if AB
= BA.
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A transformation in
which the nucleus emits an electron and a neutrino is called beta decay, an
example of nuclear radioactivity. The forces that thus come to light are those
of the so-called weak interactions.
It has been experimentally determined that for these forces the symmetry
associated with reflections in a mirror does not hold. At least in certain
circumstances, however, a remnant of this symmetry continues to hold, in which
the so-called CPT (for the initials in charge/parity/time)
theorem applies. This theorem states that basic physical laws remain of
unaltered validity when a reflection of the space coordinates as in a mirror is
combined with an interchange of positive and negative charge (which is largely
synonymous with the interchange of particles and antiparticles) and with a
reversal of the direction of time. Whether or not this symmetry law is valid
without exception is by no means fully clarified at present.
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Proceeding from the
properties of atoms and molecules that are described in terms of quantum theory,
a theory of macrophysical substance aggregates has been built using statistical
mechanics. The theories of heat, of gases, and of solid-state aggregates
(crystal lattices) have been extensively clarified. Only the liquid state still
poses certain unsolved problems for the statistical theory of heat.
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In any case,
Newtonian mechanics may be derived as a macroscopic consequence of the laws of
the mechanics of atoms, and its validity for the motions of astronomical bodies
presents no problem. It is not so simple to prove, however, that the statements
of Newtonian mechanics for rotating bodies (i.e., the mechanical laws of
centrifugal force and the Coriolis force) may be established from Einstein's
general theory of relativity. Ernst
Mach, a physicist and philosopher of science whose train of thought
has substantially fertilized the modern development of physics from the point of
view of the theory of knowledge, raised objections against Newton's idea that
centrifugal force is a consequence of the absolute rotation of a body; he
asserted instead that the rotation of a body relative to the very distant giant
mass of the universe was the true cause of centrifugal
force. This idea, often referred to as Mach's
principle, has been corroborated, though in a different form, within
the conceptual framework of Einstein's general theory. An irrotational
coordinate system--specifically, a system not rotating with respect to the fixed
stars (or, better, to the spiral nebulae)--is distinguished from a rotating
system by the difference in the metric field for the two cases (i.e., in
the properties of their respective space-times as expressed by the equation--(3)
above--for the interval between two events). It is true that the local metric
field (in the vicinity of the solar system) is influenced by the distant masses
of the universe, but of course only in the sense of a local-action principle and
therefore in no way such that the metric in the solar system is directly given
as a function of these distant masses and of their motions. |
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The question of the
precise circumstances in which Mach's principle can still be defended on the
basis of Einstein's theory is somewhat complicated and thus remains obscure. In
any case, it is certain that a deduction of this principle from Einstein's
theory can only be given in conjunction with a complete solution of the
cosmological problem; i.e., of the problem of what are the overall
geometric and dynamic properties of the universe considered in its totality. The
remaining problems involved in justifying the application of classical Newtonian
mechanics in astronomy by means of Einstein's theory contain, however, no
additional fundamental difficulties. |
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There is one more
influence of cosmological relationships upon macroscopic physics, which arises
in connection with thermodynamics. The existence of irreversible processes in
thermodynamics indicates a distinction between the positive and negative
directions in time. As
Clausius recognized in the 19th century, this irreversibility reflects a
quantity, first defined by him, called entropy,
which measures the degree of randomness evolving from all physical processes by
which their energies tend to degrade into heat. Entropy can only increase in the
positive direction of time. In fact, the increase in entropy during a process is
a measure of the irreversibility of that process. In contrast, it is true of the
quantum theory of the atom that the positive and negative directions in time are
equally justifiable (in the sense of the principle of CPT symmetry).
Consequently, it is difficult to understand how statistical mechanics can make
possible a thermodynamics in which the entropy grows with time. |
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It is true that
there are fluctuating thermodynamic phenomena, even in a system in overall
thermodynamic equilibrium--and here theory and experiment agree. Thus, the
states that arise within any small partial volume of the system may be not only
those that are thermodynamically most probable but also transitory deviations
from the most probable state. The mention of these fluctuations, however, does
not help to remove the above paradox. |
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Most physicists now
hold that, until recently, this problem was treated erroneously in the usual
textbook presentations. In the statistical theory of heat, entropy was regarded
as proportional to the logarithm of the thermodynamic probability, and students
came to regard it as a necessity of thought that nature progresses from states
of lower probability to states of higher probability.
In truth, however, the increase of entropy is a real physical property of the
positive direction in time. Nonetheless, it was supposed that shaking a vessel
containing red and white balls (or even grains of sand) in an originally ordered
condition with the two colours neatly separated must result in a condition of
extreme intermixing of balls. This result does not correspond, however, to some
necessity of thought but to an empirical property of the real universe in which
men live and experiment. |
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This
interpretation, which was held for a long time and has only quite recently been
recognized as erroneous, was allegedly supported by a famous mathematical
theorem of Boltzmann, which seemed to show that, in an ideal
gas for which the entropy--measured by its number of particles and its total
energy--was not yet at its maximum value, the entropy must increase. If
collisions of gas molecules are characterized by velocity vectors that are
mechanically allowable (both before and after the collision), and if these
vectors must satisfy both energy and momentum conservation, then what Boltzmann
actually proved is that the entropy increase follows only when a correct count
of the collision rate is made, according to which every kind of collision of gas
molecules has a frequency of occurrence proportional to the product of the
number of collision pairs that were present and the velocities that existed
before the impact.
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As one can
subsequently see, the positive direction in time is already marked out by the
collision rate count in a manner that no longer corresponds to the CPT
principle. Although it is in fact possible to reason out the continuous increase
in entropy on this basis, the paradox is not overcome. The question then remains
of how it is physically justifiable--i.e., how it can correspond to
reality--to regard this principle of collision rates as valid even though it
fundamentally contradicts the CPT principle. |
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An answer to this
paradox can now be given, thanks to the insight of modern theoreticians--among
them Hermann Bondi, a
mathematician and cosmologist--who have shown that the entropy principle must be
understood in the sense that in the universe as a whole, one definite time
direction is singled out, namely, the one for which the universe
expands. The thermodynamic distinction of a positive direction in time--with
increasing entropy on the macroscopic level and with collision rate counts on
the microscopic level--results from an expansion of the universe. Surprisingly,
the Hubble expansion of the
system of all the galaxies--so named after Edwin Hubble, an extragalactic
astronomer--thus displays physical effects right down to the level of everyday
physics; specifically, when two bodies at different temperatures are brought
into thermal contact, the temperature equalization that results is an
irreversible process corresponding to an asymmetry of the positive and negative
directions in time that depends upon the expansion of the universe. (see also cosmology
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A mathematical
discovery by Alexander Friedmann has become of great significance for the
mathematical derivation of cosmological models from Einstein's general theory of
relativity. According to
Friedmann, if the average mass density is constant throughout space, the
gravitational field equations can be satisfied by a metric that embraces a
three-dimensional space of constant curvature together with a time coordinate t
such that the radius of curvature R(t) is a definite function
of time; and these cosmologies turn out differently depending upon whether the
curvature of space is positive, negative, or zero. Among the models of the
universe that are mathematically allowable are models in which the time
coordinate may run through all values from zero to infinity, models in which the
time is limited to a finite interval, and models in which it may run from minus
infinity to plus infinity. (see also Friedmann
model) |
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For a time, many
specialists working in the field of cosmology found the so-called steady-state
theory, first projected by an astronomer, Sir
Fred Hoyle, especially convincing. In a modified version, this theory
was adapted to the Friedmann model by Bondi. By adopting the so-called perfect
cosmological principle, which holds that the broadest features of the universe
are the same at all times as well as at all places, the theory then satisfied
the unusually high symmetry or homogeneity requirements not only of a
three-dimensional space with constant time but also of the entire space-time
manifold. This high-degree homogeneity was so convincing to many authors that,
in deference to it, a fundamental deviation from Einstein's field equations was
tolerated: Bondi and Hoyle supposed that a small but constant creation of hydrogen
occurs in the intergalactic vacuum. This hypothesis was introduced in order to
achieve, in spite of the Hubble expansion of space, a mass density that remained
constant in the universe. |
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This theory, which
in spite of its deviation from Einstein's field equations certainly advocates an
allowable hypothesis worthy of consideration, no longer seems tenable, however,
because of the discovery of background radiation
with a present temperature of 3?Kelvin, which is interpreted as a remnant of an
original "big-bang" beginning of the universe. It thus appears that it
is no longer possible to uphold the steady-state theory or the perfect
cosmological principle upon which it is based. Instead, one must favour either a
Friedmann model, which has a beginning, from which it expands monotonically and
without limit; or a Lema?re model,
in which a quantity lambda,
,
called the cosmical constant, arises that is, mathematically, a constant of
integration, and physically, a force of cosmic repulsion that partially
neutralizes that of gravitational attraction, and which lends a curvature to
space even in its empty regions. For both of these models the time coordinate
increases without limit from some initial value, which would naturally be called
zero. For the beginning of time, one thinks, moreover, of a singularity R(0)
= 0 and thus of a space that at the null point of time is still a mass point.
Cyclical models that alternately expand and contract in an endless sequence have
also been discussed. (see also big-bang
model) |
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The empirical
cosmological data, some of which, indeed, are more estimated than ascertained,
seem to suggest that, in the present-day universe, the positive energy
corresponding to the total rest mass
of all the material existing in the universe may be exactly equal to the
negative gravitational
energy existing in the universe; thus, the total energy would then be equal to
zero. This interesting singularity, however, needs further support. At one time,
Dirac advocated the speculation that the total mass of the universe is not
constant in time but is increasing--at a rate somewhat slower, however, than
that in the steady-state theory. Ambartsumian's
notion concerning prestellar material, which was mentioned above (see Problems
at the formal level ), could
perhaps be considered support for this idea. Many further discussions have
followed another conjecture by Dirac, according to which the gravitational
constant G should be liable to change in the course of cosmic
development. This constant would thus have to be considered a scalar field
quantity, which in a Friedmann universe is approximately independent of the
three space variables but dependent on the time variable. In spite of extensive
theoretical deliberations on this theme, no decision has yet been reached. |
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The way has been
opened for some fundamental conjectures on certain emerging themes by the fact
that the product of the mean mass density in the universe and the gravitational
constant has the same order of magnitude as the square of the reciprocal of the
radius of curvature of the universe. The aforementioned relation between the
mass and gravitational energy in the universe presents a different expression
for this ratio. The total mass of the universe divided by the proton mass
probably has approximately the order of magnitude 1080, according to
present cosmological notions. The order of magnitude of the radius of curvature
of the universe is approximately 1040, when expressed as a multiple
of an elementary length of which the order of magnitude is approximately that of
the nuclear radius. Whether it is justifiable to presume that there is here a
functional dependence--i.e., a proportionality of M to R squared--is
a question for the present still undecidable. The speculative attempt of Dirac
to find an answer, however, is still--at least provisionally--judged with
skepticism by the majority of physicists. (P.W.J.)
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The sharp increase
in man's understanding of biological processes that has occurred in recent years
has stimulated philosophical interest in biology to an extent unprecedented
since the development of evolutionary theory in the 19th century. Biologists and
philosophers alike have devoted much attention to a variety of issues regarding
the subject matter and the methodology of biology, resulting in a sizable output
of written material, formulating philosophical questions that are still arising
and framing answers to acknowledged difficulties. Most of the problems of the
philosophy of biology are old questions now being investigated afresh in the
light of biological advances and new standards of philosophical rigour. In this
account contemporary questions will be stressed. |
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An investigation of
recent writings in biophilosophy reveals a continued preoccupation with
unanswered--some say unanswerable--questions about evolutionary theory and a
growing concern for a critical reappraisal of the question of whether biology is
an autonomous discipline unamenable to reduction to mere physical and chemical
underpinnings. Until the mid-20th century the biological sciences suffered from
a lack of attention by philosophers; the principles that were generated were far
less rigorously examined than were those of the physical sciences. There is now
renewed hope, however, for a fresh approach to the age-old puzzles regarding
life and its raison d'?re. This hope rests on the recrudescence of interest in
all biological matters as a direct result of an increased understanding of
biological processes, of the changing quality of life, of the growing awareness
of man's stewardship of the Earth, and of the exploration of space. Biology has
just begun to make the sort of impact that the physical sciences have already
made. It has generated a life technology
with genetic engineering, organ transplants, and artificial organs. Each
innovation, each technical masterstroke, each conceptual knot united emphasizes
the need for a definitive philosophy of biology, and developments toward this
goal are now under way. Good biological work has been accomplished by
investigators with varied philosophical outlooks ranging from Neo-Thomism to
skeptical naturalism. No inevitable metaphysics evolves from the study of
biology or any other natural science; nevertheless, some of the general
conclusions of biology have a philosophical interest, defining the limits of
reasonable belief about the nature of the living world. |
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Categorical
discontinuities that are recognized for the purpose of scientific methodology
often seem impossible to justify as "natural" distinctions. Many
biologists have noted, for example, that it is easier to study life
than it is to define it. Properties such as metabolism and reproduction
undeniably characterize organisms and might be said to define them, yet such a
definition is arbitrary to the extent that such properties are logically
independent. What is true of all life forms today may not have been true of the
very earliest ones and, what is more, might not be true of extra-terrestrial
ones that might be encountered in the future. There is not as yet a set of
nonarbitrary characteristics that mark the distinction between living and
nonliving systems. Moreover, in the course of analysis, it becomes necessary to
arrange all of the phenomena of nature in a more or less linear, continuous
sequence of classes and then to describe events occurring in the class of more
complex phenomena in terms of events in the classes of less complex phenomena
(principle of hierarchical continuity). Within each class, however, there are
numerous interrelations observed between events of the same order of complexity.
It is thus possible to recognize a number of more or less autonomous
disciplines, each permitting generalization, but ordered so that the more
complex events treated by one discipline can also be analyzed in terms of less
complex events treated by another discipline. It is possible, for example, to
establish a body of generalizations about human society independent of the
behaviour of individual persons; a number of generalizations about individual
behaviour without consideration of the physiology of the sensory, conductor, and
effector mechanisms involved; and a large body of generalizations about muscle
or nerve physiology without considering the molecular mechanisms involved. A
particularly striking feature of the hierarchy is that an increase in complexity
is coupled with the emergence of new characteristics. The origin and development
of life from small systems that synthesized biochemicals to organisms that
perform highly complicated functions suggests that the hierarchical arrangement
of nature and the sciences is correlated with the temporal order of evolution.
The maintenance of a steady state by metabolism, reproduction, responsiveness,
modification of response by experience, tradition, and social phenomena are just
some of the more dramatic examples of emergent phenomena. The emergence of new
qualities as evolution proceeds might generally characterize the universe. |
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Moreover, photosynthesis,
on the one hand, and reproduction followed by natural selection, on the other,
provide a mechanism by which physically less probable systems can emerge locally
from physically more probable ones. Though it frequently has been supposed that
physical evolution is at an end, there is no reason to suppose that this is true
of social development, for which Sir
Julian Huxley, a biologist, philosopher, and educator, provided an evolutionary
context. In his Romanes Lectures, published in 1943, Huxley wrote: |
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It
is only through social evolution that the world-stuff can now realize radically
new possibilities. Mechanical interaction and natural selection still operate,
but have become of secondary importance. For good or evil, the mechanism of
evolution has in the main been transferred [in man] onto the social or conscious
level. . . . The slow methods of variation and heredity are outstripped by the
speedier processes of acquiring and transmitting experience. . . .
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And
in so far as the mechanism of evolution ceases to be blind and automatic and
becomes conscious, ethics can be injected into the evolutionary process. Before
man that process was merely amoral. After his emergence onto life's stage it
became possible to introduce faith, courage, love of truth, goodness--in a word
moral purpose--into evolution. It became possible, but the possibility has been
and is often unrealized. |
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It may well be that
social evolution is only in its early stages. These stages, moreover, have for
the most part taken place in a period during which systematic knowledge was
undeveloped. A Russian mineralogist, Vladimir
Vernadsky, the founder of biogeochemistry, regarded the envelope of
the Earth as passing from a stage determined primarily by biological processes
to one determined by conscious human effort. He called this layer of
consciousness the no?phere.
The concept was later extended, notably by Pierre
Teilhard de Chardin, a French priest and paleontologist, who began
the building of a new philosophic bridge between biology and religion. |
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Questions about the
character of biological systems and of the biological world merge with those
about the concepts and methods required for their understanding. Although the
two cannot be wholly separated, in this account those matters most clearly
related to the substantive philosophical aspects of biology will be stressed.
Methodological issues will be touched on in respect to the concepts being
elucidated. |
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Space exploration
has directly influenced the development of life-detecting devices. This
technological need spurred intensive study regarding the kinds of evidence
living things display reflecting their aliveness. In his Chance and Necessity
(1972) Jacques Monod, a
biologist, deals with the invariance of genetic endowment, morphological
autonomy, reproductive invariance, and teleonomy (the
tendency to have a purpose or project written into their molecules) as the major
properties of living systems; he considers that they involve the chance and
necessity that determine the course and character of the entire biological
world.
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Philosophers have
long deliberated over the definitive features of living systems. The distinction
between living and nonliving, which was widely discussed at the turn of the 20th
century, has lost much of its interest for current biology. A growing
conviction, intuitively felt by many biologists, is that no clear line can be
drawn between the living and the nonliving. The bridge between what is and is
not obviously alive consists of a range of problematic agents, including viruses
and genes, which appear to be living at times and nonliving at other times. |
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Basically and
traditionally, there are three distinct philosophical stands regarding the
biological nature of life: vitalism,
mechanism, and organicism. |
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Essentially,
vitalism holds that there exists in all living things an intrinsic
factor--elusive, inestimable, and unmeasurable--that activates life. In its
classic form, as espoused by many biologists at the turn of the 20th century--in
particular, by Hans Driesch,
a German biologist and philosopher--it has suffered severe criticism. Ernest
Nagel, a philosopher of science, rang its death knell in 1951, when
he wrote in Philosophy and Phenomenological Research (11:327 ff.): |
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Vitalism
of the substantival type . . . is now a dead issue . . . less, perhaps, because
of the methodological and philosophical criticism that has been leveled against
the doctrine than because of the infertility of vitalism as a guide in
biological research and because of the superior heuristic value of alternative
approaches.
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And whereas most
biologists concur in renouncing this so-called na?e vitalism, some continue to
espouse a so-called critical vitalism, perhaps indistinguishable from organicism
(see below). |
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Simply stated, the
view of the mechanists is
that organisms are no different from subtle machines: the whole is the sum of
its parts, which are arranged in such a way that an internal energy source can
move them in accordance with a built-in program of purposeful action. In the
mechanist's view, advances in molecular
biology corroborate this claim and demonstrate that in principle
organisms are no more than complicated physical systems. This is, in essence,
the reductionist position,
which states that biological principles can be reduced to physical and chemical
laws. Antireductionists, of course, contend that molecular biology cannot
explain all aspects of living forms. |
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It has often been
said that, whereas biologists may think as vitalists--and hold the conviction
that organisms are more than just complex machines--they perforce become
practicing mechanists in the laboratory, required by the demands of scientific
inquiry to view their experiments in terms of the measurable parameters of
physics and chemistry. K.F. Schaffner, an American philosopher, suggested in
1967 that, even though reductionism may be correct, a better strategy may be to
strive toward an independent biology. |
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The basic claim of organicism
is that organisms must be interpreted as functioning wholes and cannot be
understood by means of physics and chemistry alone. Few scientists today call
themselves organismic biologists or endorse the doctrines put forward by such
organismic theorists as Ludwig von Bertalanffy and Edward Stuart Russell.
Nevertheless, most antireductionists subscribe at least to part of the
organismic doctrine, in particular to its wholistic claim. Russell, a foremost
proponent of organicism, stated in his work The Interpretation of Development
and Heredity (1930):
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Any
action of the whole organism would appear then to be susceptible of analysis to
an indefinite degree--and this is in general the aim of the physiologist, to
analyze, to decompose into their elementary processes the broad activities and
functions of the organism. But . . . by such a procedure something is lost, for
the action of the whole has a certain unifiedness and completeness which is left
out of account in the process of analysis. . . . In our conception of the
organism we must . . . take account of the unifiedness and wholeness of its
activities . . . since . . . the activities of the organism all have reference
to one or other of three great ends, and that both the past and the future enter
into their determination. . . . Bio-chemistry studies essentially the conditions
of action of cells and organisms, while organismal biology attempts to study
the actual modes of action of whole organisms, regarded as conditioned by, but
irreducible to, the modes of action of lower unities.
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In some special
sense, then, an organism is regarded as being more than a simple sum of its
parts; an additional "something" has accrued to it as a result of the
unique arrangement of its components. As Morton O. Beckner,
a philosopher of biology, asserted in an article in The Encyclopedia of
Philosophy (5:549):
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In
the history of biology it is difficult to disentangle vitalistic and organismic
strands, since both schools are concerned with the same sorts of problems and
speak the same sort of language. The distinction between them was drawn clearly
only in the twentieth century. Organismic biology may be described as an attempt
to achieve the aims of the murky organismic-vitalistic tradition, without appeal
to vital entities.
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Further (p. 551): |
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Organismic
biology is to be interpreted as a series of methodological proposals, based on
certain very general features of the organism--namely, the existence in the
organism of levels of organization with the biological ends of maintenance and
reproduction. These features are sufficient to justify "a free, autonomous
biology, with concepts and laws of its own," whether or not the higher
levels are ultimately reducible to the lower ones.
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The
concept of an organism as a cybernetic,
or automatic-control, system is currently influential in biology. |
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The
holistic concept of an organism--i.e., the theory that the determining
factors in biology are its irreducible wholes--owes its success primarily to the
existence of control and regulation mechanisms operating at the molecular level
that determine development and behaviour. The character of such systems at all
levels of analysis--molecular through total organism--is nothing other than a
sophisticated kind of cybernetics. Holism
and reductionism are similar in this respect. Closely allied to organicism is
the old problem of emergent properties dealt with earlier: at each successive
level of organization, qualities emerge that cannot be anticipated by the
components and that confer an added dimension to each hierarchical level in the
biological world. |
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A
theoretical and methodological program called general systems theory--presented
in its fullest and most persuasive form by Bertalanffy--is
an extension of the tenets of organismic biology. It is an attempt to provide a
common methodological approach for all of the sciences, based upon the idea that
systems of any kind--physical, biological, psychological, and social--operate in
accordance with the same fundamental principles. Ideally, it should be possible
to deduce the principles applying to a particular sort of system from the more
general ones. This approach is one still very much in need of development. |
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Attributions
of purpose (teleology)
appear frequently in biological writing. Not only do biologists say that parts
of organisms have a purpose with respect to the whole, but some hold that life
itself is inherently purposive. But the term purpose is both vague and
ambiguous. That every biological system--from self-replicating molecules (DNA)
to biotic communities--involves specific and identifiable functions is
undeniable. But whether, or in what way, functional ends like the reproduction
of a cell resemble human intentions or purposes is a matter of some controversy.
Even if this matter were settled, a larger question would still remain, viz.,
whether a biological system as a whole can have a goal that is in some way
similar to a human goal--i.e., whether it is programmed with an ultimate
purpose. Although resolution of this matter has long been and will continue to
be a critical point in the philosophy of biology, much has been done to clarify
the issues involved. |
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3.1.2.3.1
Teleology
and determinism.
Vitalists
and those who subscribe to a Lamarckian view of evolution involving the
inheritance of acquired characteristics claim that evolution involves a
deterministic finalism, or directedness toward an end. Most evolutionists--among
them George Gaylord Simpson--reject
that claim and hold that natural selection is the non-random element in
evolution, that which gives evolution direction. Other evolutionists--among them
Theodosius Dobzhansky--argue
that the chance factors in mutation and selection, in addition to the
unpredictability of environmental change, make it impossible to formulate
deterministic laws even in experimental populations, let alone in natural
populations. Similar considerations by others have led to the claim that
evolutionary biology is a paradigm of an after-the-fact exploratory science and
that the course of evolution can never be predicted. |
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Whether
biological species can be said to have a real existence in the world is a
question that has been receiving much consideration. The issue may be posed in
the words of Benjamin Burma, a paleontologist, who, writing
in Evolution (3:369), asked:
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What,
then, is a species? It would seem thus far to be the whole of any one series of
breeding populations. . . . [But the] definition as it stands unfortunately puts
all living and fossil animals in one species, since there is a continuity of
germ-plasm back from John [an individual animal] to the original primordial
cell, and from it forward to every living animal (not to mention plant). Thus,
if we ignore time, we end up with only one species. . . .
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The
temporal difficulty, however, is not the only stumbling block to the question of
species reality; for, if the species is redefined as the whole of any one series
of breeding populations as it exists at any one time, then there is an infinity
of species, since time itself is infinitely divisible. On the basis of these and
other objections, some biologists have concluded that species have only a
subjective existence merely as convenient labels for arbitrary assemblages and
have only a minimum of biological significance. On the other hand, there are
proponents of the idea that species have an objective reality. Ernst
Mayr, a U.S. evolutionist representing the latter group, has
written--also in Evolution (3:372): |
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In
all multidimensional situations an inference has to be made (Simpson, 1943) on
the basis of the objective species of the non-dimensional system. The
subjectivity of this expanded species concept by no means invalidates the
species concept per se. The species of the local naturalist or of the
paleontologist within a given horizon is clearly delimited against other species
and can thus be considered as having objective reality.
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Although
the controversy is confused by semantic difficulties, one of the chief
contributions of the philosophy of biology has, in fact, been to separate mere
linguistic puzzles from matters of substance. Many taxonomists are guilty of
ambiguity of reference; they often fail to distinguish their entities clearly,
with the result that there is widespread befuddlement over just what stand is
held by whom. The problems are now clearer than they have ever been, and with
few exceptions biologists and philosophers tend to agree about the nature of
biological species and the definition of the species category. |
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Although
most of the issues connected with evolution as a theory are methodological ones,
two issues go beyond the limits of logic. Some philosophers have tried to
demonstrate, for example, that evolutionary theory is circular and offers no
real understanding of the process of evolution. Others have argued that the
notions of types of organisms must be used to understand evolution and that
evolutionary change takes place when a new type emerges. |
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Two
clear viewpoints regarding evolutionary theory have come to the fore since 1950.
One is expressed in detail by George Gaylord Simpson, in his work The Major
Features of Evolution (1953), and the other is put forward by a
paleontologist, Otto Schindewolf,
in his Grundfragen der Pal?ntologie (1950). In 1959, Marjorie Grene,
a philosopher of biology, writing in the British Journal of the Philosophy of
Science (9:11 ff.), summarized their positions as follows:
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Professor
Simpson is the principal American spokesman of neo-Darwinism. . . . He sees
evolution as a continuous series of minute changes in innumerable directions, in
which all alterations of any significance, larger as well as smaller, quicker as
well as slower, are determined by the great cooperating "pressures" of
mutation, geographical isolation, and selection, with adaptation as the
universal effect, and criterion, of systematic change. The basic concept,
ultimately is variation in the occurrence of genes; out of such variations all
the systematic relations of living things have been gradually evolved.
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Schindewolf's
principles are simpler. He sees typical shapes, and sees again and again what
appear to be new shapes. Therefore he assumes that living things are able to
originate novel types. Mutation, he agrees, must have been the mechanism by
which they originated; but the adaptive control of mutation occurs only within,
not between types. The basic pattern is of change from type to type, and always,
as we have seen, with the more general appearing before its specialised
subdivisions. |
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The
controversy between these two opposing viewpoints is a complex one filled with
both philosophical and scientific issues. In the opinion of most biologists,
Schindewolf's view is persuasive only with respect to the paleontological
evidence and is not supported by the experimental study of evolution in current
organisms. Most of them thus tend to accept the synthetic theory in more or less
the form expressed by Simpson. It remains possible, however, that the process
that Schindewolf is talking about is fundamentally different from that explored
in population genetics and that typostrophic mutations
are so rare, on the time scale of man, as to be beyond hope of detection in the
laboratory. |
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Very
few attempts have been made in recent years to employ the concept of evolution
as a scheme for viewing all knowledge and experience. Sir Julian Huxley, who
remains one of the best representatives of such an effort, continues to claim
that the entire universe is in a process of evolution, which, however, has
different aspects, viz., physical, biological, and social. Life and nonlife
alike must be understood as part of the process of cosmic evolution, and from
this follows a host of metaphysical and ethical implications. The other chief
representative of this viewpoint is the evolutionist priest Teilhard
de Chardin, who has woven into the fabric of cosmic evolution the
panoply of a Christocentric religion that sees the perfection of all things in
an "Omega" point toward which evolution is moving. |
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Metaphysics
of the more piecemeal kind--exploring the implications that biological knowledge
has on beliefs and attitudes--is fostered by Simpson, a consistent antagonist of
Huxley and Chardin. Simpson suggests, for instance, that knowledge of man's
origins and of the process that has brought him to his current state in no way
threatens belief in his own uniqueness. Man is an animal, but a very special
sort of animal. Other matters of a similar kind--purpose in nature and man's
evolutionary future--are considerations that constitute the implications of
biology in general and of evolutionary biology in particular. |
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3.1.2.5.1
The
question of innate aggressiveness.
One
of the best known issues threatening accepted beliefs about moral responsibility
is probably that raised by the proponents of the theory of innate aggression, in
particular by such spokesmen as Konrad
Lorenz, an Austrian student of animal behaviour, and Robert Ardrey,
a U.S. writer. If there is an instinct for aggressiveness,
then the notion that it is acceptable to blame individuals and society for
outbreaks of violence or war loses its validity. The thrust must then be
elsewhere: not in faultfinding but in shoring up against what is felt to be
pedestrian and inevitable. As Ardrey puts the theory in his African Genesis (1961):
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But
we were born of risen apes, not fallen angels, and the apes were armed killers
besides. And so what shall we wonder at? Our murders and massacres and missiles,
and our irreconcilable regiments? Or our treaties whatever they may be worth;
our symphonies however seldom they may be played; our peaceful acres, however
frequently they may be converted into battlefields; our dreams however rarely
they may be accomplished. The miracle of man
is not how far he has sunk but how magnificently he has risen. We are known
among the stars by our poems, not our corpses.
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Raymond
Dart, a South African anatomist and anthropologist, in an article entitled
"The Predatory Transition from Ape to Man," published in the International
Anthropological and Linguistic Review (1:201-208), expressed the thesis of
innate depravity on which Ardrey's more popular presentation is based. |
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Another
aspect of the innate aggression inherited from man's primate forebears is
militant enthusiasm, which Lorenz described in Das sogenanannte B?e: zur
Naturgeschichte der Aggression (1963; Eng. trans., On Aggression, 1966):
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In
reality, militant enthusiasm is a specialized form of communal aggression,
clearly distinct from and yet functionally related to the more primitive forms
of petty individual aggression. Every man of normally strong emotions knows,
from his own experience, the subjective phenomena that go hand in hand with the
response of militant enthusiasm. A shiver runs down the back and, as more exact
observation shows, along the outside of both arms. One soars elated, above all
the ties of everyday life, one is ready to abandon all for the call of what, in
the moment of this specific emotion, seems to be a sacred duty. All obstacles in
its path become unimportant; the instinctive inhibitions against hurting or
killing one's fellows lose, unfortunately, much of their power. Rational
considerations, criticism, and all reasonable arguments against the behavior
dictated by militant enthusiasm are silenced by an amazing reversal of all
values, making them appear not only untenable but base and dishonorable. Men may
enjoy the feeling of absolute righteousness even while they commit atrocities.
Conceptual thought and moral responsibility are at their lowest ebb. As a
Ukrainian proverb says: "When the banner is unfurled, all reason is in the
trumpet."
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Equally
notable opponents of the theory of innate aggression see it much as M.F.
Ashley Montagu, a British-U.S. anthropologist, does, as
"original sin revisited," and deplore the tendency to neglect
authoritative studies in favour of simplistic popularization. In Man and
Aggression (1968), he writes: |
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While
the findings of these disciplines [anthropology and the behavioral sciences] are
wholly opposed to the deeply entrenched view that man is an innately aggressive
creature, most people tend to dismiss these findings out of hand or ridicule
them as a rather eccentric idealistic heterodoxy, which do not deserve to become
generally known. In preference to examining the scientific findings they choose
to cast their lot with such "authorities" as William Golding who, in
his novel Lord of the Flies, offers a colorful account of the allegedly
innate nastiness of human nature, and Robert Ardrey who, in African Genesis and
more recently in The Territorial Imperative, similarly seeks to
show that man is an innately aggressive creature. . . .
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.
. . when through the distorting glass of his prejudgments he looks at a tool it
becomes not simply a scraper but a weapon, a knife becomes a dagger, and even a
large canine tooth becomes "the natural dagger that is the hallmark of all
hunting animals," while in "the armed hunting primate" it becomes
"a redundant instrument." "With the advent of the lethal weapon
natural selection turned from the armament of the jaw to the armament of the
hand." But the teeth are no more an armament than is the hand, and it is
entirely to beg the question to call them so. Virtually all the members of the
order of primates, other than man, have large canine teeth, and these animals,
with the exception of the baboons, are predominantly vegetarians, . . . that
such teeth may, on occasion, serve a protective purpose is entirely secondary to
their main function, which is to rip and shred the hard outer coverings of plant
foods. |
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Further
responses to Ardrey's and Lorenz' thesis are the interpretations of field
studies of primate groups, such as those on the gorilla, chimpanzee, and
orangutan. These researches suggest that the majority of such groups are
singularly free of belligerence. According to Montagu, |
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The
myth of the ferocity of "wild animals" constitutes one of Western
man's supreme rationalizations, for it not only has served to
"explain" to him the origins of his own aggressiveness, but also to
relieve him of the responsibility for it--for since it is "innate,"
derived from his early apelike ancestors, he can hardly, so he rationalizes, be
blamed for it! And some have gone so far as to add that nothing can be done
about it, and that therefore wars and juvenile delinquents, as Mr. Ardrey among
others tells us, will always be with us! From one not-so-minor error to another
Mr. Ardrey sweeps on to the grand fallacy.
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The
matter remains moot; but there appears to be a growing consensus that, given a
certain genetic constitution--and within the bounds of that endowment--whatever
man is, he learns to be, especially in respect to values, morality, and customs.
Baser appetitive needs, however, may have a genetic component that is greater
than an environmental one. |
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New
understanding of environmental factors and the consequences of man's actions
with respect to them has made it clear that man has acquired responsibilities
that he did not recognize before. It has become increasingly accepted that
standards and values with respect to the environment must be established; this
is perhaps the most dramatic case in which recent biological knowledge has
generated a crisis of a moral kind. The classic work Science and Survival (1966)
by a biologist, Barry Commoner, is particularly noteworthy
in connecting theoretical and philosophical issues about reductionism and holism
to practical matters of environmental
understanding and problem solving.
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The
metaphysical issue of man's place in nature is now being construed as one that
requires that man make value decisions, assign responsibilities, and plan for
the future of his planet. Environmental problems have become intertwined with
problems of social planning, racial tension, transportation and housing crises,
genetic engineering, and a host of other current concerns. |
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The question of
whether nature provides guides to the actions of humankind has held a
fascination for many biologists. Those who call themselves evolutionary
ethicists say that it does. The defenders of evolutionary ethics contend that
external moral standards exist in the facts and process of evolution. |
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Toward the end of
the 19th century, Herbert Spencer,
in England, and others advanced a series of principles that came to be called Social
Darwinism. It espoused such ideas as the inevitability of progress,
survival of the fittest, and the struggle for existence, expressions that have
become bywords although they have since been discredited in their original
sense, as applied to social phenomena. Social Darwinism, as C.H.
Waddington, a biologist, explains in his book The Ethical Animal (1960,
has been superseded by (see also ethics)
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.
. . the more recent phase of evolutionary ethical thought beginning in the early
1940s, [which] comprises a number of rather different methods of approach. At
one extreme we have discussions framed in terms of extremely wide scope, which
treat of evolution not only in the animal world but throughout the cosmos, and
attempt to relate such broad concepts to man's religious and spiritual life. The
pre-eminent example of this tendency in recent years is Teilhard de Chardin, but
a rather similar approach can be found in the works of several biologists, such
as Conklin, Holmes, and Huxley. The opposite tendency, which of course is also
found expressed to various extents in these authors, particularly in Julian
Huxley, is the attempt to demonstrate, in a logically coherent argument, a real
connection between evolutionary processes and man's ethical feelings.
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Some biologists
continue to insist, therefore, that biological facts can provide a yardstick by
which to measure the morality of a given course of action. Julian
Huxley, for one, has long claimed that moral principles can be found
in nature and in the evolutionary process in particular: |
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When
we look at evolution as a whole, we find, among the many directions which it has
taken, one which is characterized by introducing the evolving world-stuff to
progressively higher levels of organization and so to new possibilities of
being, action, and experience. This direction has culminated in the attainment
of a state where the world-stuff (now moulded into human shape) finds that it
experiences some of the new possibilities as having value in or for themselves;
and further that among these it assigns higher and lower degrees of value, the
higher values being those which are more intrinsically or more permanently
satisfying, or involve a greater degree of perfection.
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Huxley further
asserts that, although the Golden Rule, the policy of action based on
sympathy--doing as one would be done to by others--may be an immediate good, it
ultimately leads to the suppression of those qualities most needed for survival
and the continuation of a species. Rather, he argues: |
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The
facts of nature, as demonstrated in evolution, give us assurance that knowledge,
love, beauty, selfless morality, and firm purpose are ethically good. . . . In
the broadest possible terms evolutionary ethics must be based on a combination
of a few main principles: that it is right to realize ever new possibilities in
evolution, notably those which are valued for their own sake; that it is right
both to respect human individuality and to encourage its fullest development;
that it is right to construct a mechanism for further social evolution which
shall satisfy these prior conditions as fully, efficiently, and as rapidly as
possible.
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Simpson,
however, contends, in the article "Biological Sciences," in The
Great Ideas Today (1965): |
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The
facts and the processes of evolution are neither ethical nor unethical. The
questions of good or bad are simply irrelevant to this field, with the important
reservation that evolution has produced a species, Homo sapiens, concerned
with ethics. Denial of man's naturalistic origin and animal nature is flatly
false, and any ethic based on such denial is invalid. Evolution controverts
primitive creation myths, but it is consistent with higher values in the
Judeo-Christian tradition and those in most now-current religions and
philosophical systems. One need only think of the brotherhood of mankind--a
biological fact, not only an ethical idea.
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Beyond
such considerations as those, efforts to combine science and religion may be
noble in intention but usually end up distorting or stultifying both. One of the
most striking examples at present is the cult, as it may fairly be called, of
Pierre Teilhard de Chardin. He preaches--necessarily posthumously, for the Roman
Catholic Church suppressed his views during his life--a mystical Christianity
ostensibly derived from evolutionary principles. But since the mysticism is
primary, the evolutionary principles are distorted and downright falsified for
seeming coherence with the nonscientific, nonnaturalistic premises. In turn, the
mystical views advanced as having that false basis are thereby vitiated. The
result (in my opinion) has been a disservice to true religion and to true
science. |
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At
the same time, no one can deny the purity of Father Teilhard's intentions or the
correctness of his view that evolution and religious feeling should be
considered congruent aspects of the nature of man. It is almost as irrational to
deny evolution as to deny gravity. The management of life and the goals of
aspiration, to be sane, must take account of all such truths of nature. They
need not thereby become brutal or earthbound. |
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(J.R.Mn./ R.C.Y.) |
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