2. Nominalism and Its Influence. Most historians are
agreed that some break with Aristotle was necessary
before the transition could be made from natural phi-
losophy to science in the classical sense. One step
toward such a break came with the condemnation, in
1277, by Étienne Tempier, Bishop of Paris, of 219
articles many of which were linked to an Aristotelian-
Averroist cosmology. Concerned over God's omni-
potence, the bishop effectively proclaimed that several
worlds could exist, and that the ensemble of celestial
spheres could, without contradiction, be moved (by
God) in a straight line. The general effect of his con-
demnation was to cause many who were uncritically
accepting Aristotle's conclusions as demonstrated and
necessarily true to question these. The way was thus
opened for the proposal and defense of non-Aristotelian
theses concerning the cosmos and local motion, some
with important scientific ramifications.
Another step came with the rise of nominalism or
terminism in the universities. Under the auspices of
William of Ockham and his school, this movement
developed in an Aristotelian thought context but
quickly led to distinctive views in logic and natural
philosophy. Its theory of supposition questioned the
reality of universals or “common natures,” generally
admitted by Aristotelians, and restricted the ascription
of reality to individual “absolute things” (res absolutae),
which could be only particular substances or qualities.
Quantity, in Ockham's system, became merely an ab
stract noun: it cannot exist by itself; it can increase
or decrease without affecting the substance, as is seen
in the phenomena of rarefaction and condensation; and
by God's absolute power it can even be made to disap-
pear entirely, as is known from the mystery of the
Eucharist. Thus, with Ockham, quantity became a
problem more of language than of physical science;
his followers soon were involved in all manner of
linguistic analyses relating to quantity, but not infre-
quently the physical problems involved got lost in a
maze of logical subtleties.
Ockham's treatment of motion went along similar
lines. Convinced that the term “local motion” desig-
nates only the state of a physical body that may be
negatively described as not at rest, he effectively de-
nied the reality of motion. Moreover, since motion is
not a real effect, it does not require a cause, and
hence the Aristotelian rule “whatever moves is moved
by another” (quidquid movetur ab alio movetur) is no
longer applicable to it. Some have seen in this rejection
of motor causality a foreshadowing of the law of inertia
or even the principle of relativity (Sir Edmund Whit-
taker, E. J. Dijksterhuis). Undoubtedly there are some
affinities between Ockham's analysis and those of classi-
cal and modern mechanicians, but the identification
need not be pressed. Ockham's more direct contri-
bution would seem to lie in his preparing the way for
sophisticated, if highly imaginative, calculations of
spatiotemporal relationships between motions with
various velocities. These calculations opened the path
to considerable advances in kinematics, soon to be
made at Merton College in Oxford.
Nominalism quickly spread from Oxford to the
universities on the Continent, where it merged its
thought patterns with both “orthodox” and “hetero-
dox” (from the viewpoint of the Christian faith) schools
of Aristotelianism. From this amalgam came a renewed
interest in the problems of physical science, a consid-
erably revised conceptual structure for their solution,
and a growing tolerance of skepticism and eclecticism.
Most of the fruits were borne in mechanics and astron-
omy, but some were seen in new solutions to the prob-
lems of the continuum and of infinity. Nicholas of
Autrecourt is worthy of mention for his advocacy of
atomism—at a time when Democritus' thought was
otherwise consistently rejected—and for his holding a
particulate theory of light. His skepticism generally has
led him to be styled as a “medieval Hume” and as
a forerunner of positivism.
