2. Ancient Conceptions. In fact, the earliest known
thesis of indeterminacy restricted this notion to a
definite realm of applicability. According to Plato's
Timaeus (28D-29B) the Demiurge created the material
world after an eternal pattern; while the latter can
be spoken of with certainty, the created copy can be
described only in the language of uncertainties. In
other words, while the intelligible world, the realm
of ideas, is subject to strict laws, rigorous determi-
nations and complete predictability, the physical or
material world is not. However, even disregarding this
dichotomy of being, Plato's atomic theory admitted an
a-indeterminacy in the subatomic realm, whereas in
the world of atoms and their configurations to higher
orders determinacy was reinstated. “However strictly
the principle of mathematical order is carried through
in Plato's physics in the cosmos of the fixed stars as
well as in that of the primary elements,” writes an
eminent Plato scholar, “everything is indeterminate in
the realm below the order of the elementary atoms.
... What resists strict order in nature is due to the
indeterminate and uneven forces in the Receptacle”
(Friedländer, 1958). Indeed, for P. Friedländer Plato's
doctrine of the unintelligible subatomic substratum is
“an ancient anticipation of a most recent develop-
ment,” to wit: W. Heisenberg's uncertainty principle.
Still, whether such a comparison is fully justified may
be called into question.
An undisputable early example of indeterminacy, in
any case, is Epicurus' theory of the atomic “swerve”
(clinamen). Elaborating on Democritus' atomic theory
and his strict determinism of elementary processes,
Epicurus contended that “through the undisturbed void
all bodies must travel at equal speed though impelled
by unequal weights” (Lucretius II, lines 238-39),
anticipating thereby Galileo's conclusion that light and
heavy objects fall in the vacuum with the same speed.
Since consequently the idea that compounds are
formed by heavy atoms impinging upon light ones had
to be given up, “nature would never have created
anything.” To avoid this impasse, Epicurus resorted to
a device, the theory of the swerve, which some critics,
such as Cicero and Plutarch, regarded as “childish”;
others, like Guyau or Masson, as “ingenious.” “When
the atoms are travelling straight down through empty
space by their own weight, at quite unpredictable
times and place (
incerto tempore incertisque locis), they
swerve ever so little from their course, just so much
that you can call it a change of direction” (Lucretius
II, lines 217-20). To account for change in the physical
world Epicurus thus saw it necessary to break up the
infinite chain of causality in violation of Leucippus'
maxim that “nothing occurs by chance, but there is
a reason and a necessity for everything.” This indeter-
minacy which, as the quotation shows, is both an
a-indeterminacy and a u-indeterminacy, made it possi-
ble for Epicurus to imbed a doctrine of free will within
the framework of an atomic theory.
In the extensive medieval discussions (Maier, 1949)
on necessity and contingency which were based, so far
as physical problems were concerned, on Aristotle's
Physics (Book II, Chs. 4-6, 195b 30-198a 13), the
existence of chance is recognized, but not as a breach
in necessary causation; it is regarded as a sequence of
events in which an action or movement, due to some
concomitant factor, produces exceptionally a result
which is of a kind that might have been naturally, but
was not factually, aimed at (Weiss, 1942). The essence
of chance or contingency is not the absence of a neces-
sary connection between antecedents and results, but
the absence of final causation. Absolute indeterminacy
in the sense of independence of antecedent causation
was exclusively ascribed to volitional decisions.
