1 The Birth of Science - MSRI

10.11 Determinism and Chance 275
vived for a long time, and have been regarded as purely philosophical,
mostly “Stoic”, in origin. They are reported, for example, by Macrobius,
though he attributes them to Pythagoras. 164 They may have been remnants
of a gravitation-based dynamical astronomy, no longer understood.
If we look into why these ideas were attributed to the Stoics, we find that
the primary reason is that their origin can be traced back to Posidonius —
just as in the case of the analogy between earth and sling. Note that Posidonius
(who, besides having built planetaria, seems to have been the last
scholar to be seriously interested in tides 165 ) headed a school at Rhodes not
long after Hipparchus had been active there. As for the connection with
Pythagoras, besides the general tendency of neo-Pythagoreans to credit
him as the source of all sorts of knowledge, it may be explained also by
the confusion between Hipparchus and Hippasus (page 210).
10.11 Determinism and Chance
The following passage of Laplace, contained in his Essai philosophique sur
les probabilités (1825), is very often cited as a nutshell statement of nineteenth-century
determinism, and is often considered as a “determinist
manifesto”:
An intelligence who, for a given moment, knew all the forces that
act in nature and the respective situation of its component beings, if page 343
it also were ample enough to analyze these data, would encompass
under the same formula the motions of the largest bodies in the universe
and those of the lightest atom. Nothing would be uncertain to
that intelligence; the future, just like the past, would lie open before
its eyes. The human mind, in the perfection to which it has been able
to take astronomy, offers a pale reflection of such an intelligence.
By Laplace’s time determinism already had a very old history. It goes
back at least to Democritus 166 and underwent interesting developments at
the hands of the Stoics. 167 Cicero, reporting Stoic ideas, writes:
Moreover, since everything is caused by fate (as is shown elsewhere),
if there could be a mortal able to grasp in his mind the chain of
all causes, nothing at all would escape his knowledge: for he who
knows the causes of future events must perforce know also what
164
In particular in his commentary on Cicero’s Somnium Scipionis.
165
See Strabo, Geography, III, v, 9.
166
Democritus, A68 ff. in [Diels: FV], vol. II.
167
One particularly interesting source about Stoic determinism is the De fato by Alexander of
Aphrodisias. Fragments 915–951 and 959–964 in vol. II of [SVF] are devoted to this subject.
Revision: 1.11 Date: 2003/01/06 02:20:46