3. A Seventeenth-Century Theory of Matter: Isaac
Newton. A. N. Whitehead's characterization of the
seventeenth as the “century of genius” seems eminently
fitting. To the men whose collective intellectual
achievement he regarded as perhaps unparalleled—
Galileo, Descartes, Huygens, and Newton—the student
of matter might well wish to add the indefatigable and
resourceful figure of Robert Boyle. But admitting his
great indebtedness to his predecessors and contem-
poraries, even on specific achievements with which his
name is connected, Isaac Newton must stand pre-
eminent for the magnitude of his achievements and
their impact upon modes of thought. If, through some
barely conceivable quirk of intellectual history, he had
been unable to effect his observationally and mathe-
matically fortified synthesis of dynamics and astron-
omy, the scientific revolution might possibly have fal-
tered and even faded.
Once Newton's success in deriving Kepler's laws of
planetary motion—and explanations of a vast range of
other phenomena as well—from a unified mechanics
of gravitational and inertial forces had been appreci-
ated, the optimism and methodological confidence of
the natural philosophers were irresistible. From the
hither side of this achievement, particularly when
historically we observe the selective accumulation of
what were to become parts of the synthesis, it seems
inevitable, and it may be worthwhile to consider one
conceptual complication relevant to the ideas of
matter. On the one hand Newton's system required
that one should conceive every particle of matter in
the universe as gravitationally attracting every other
according to the law of inverse squares; on the other
hand the counterbalancing centrifugal forces operated
inertially, i.e., as if no external forces whatever affected
the mobile. The final equation for planetary motion,
therefore, involved combining the maintenance of the
universal interaction of all matter with the hypothesis
of how it would behave on the contrary assumption
that there was no other matter with which the mobile
in question could interact.
This was a pitch of abstraction of which a rather
ossified Aristotelianism—and some successor doctrines
as well—showed themselves quite incapable. This point
may also serve to illustrate the ambiguous sense in
which Newton's system triumphed through its “sim-
plicity”: as Butterfield remarks, it was simple in re-
quiring relatively few ad hoc assumptions about the
sort of forces involved; it was the reverse of simple
in the mathematics necessary to compute the concrete
resultant of forces.
In regard to his evolving concepts of matter, Newton
never called himself an atomist though he did hypoth-
esize that “God in the beginning formed matter in
solid, massey, hard, impenetrable, moveable particles”
with varying “sizes... figures, and... other proper-
ties” and in varying “proportions to space” (Opticks
iii.1). He was closer to the ancient theory than Boyle
in one respect: whereas Boyle had thought of atoms
as flexible even to the point of actual division, Newton
insisted on their indivisibility, “that Nature may be
lasting,” arguing that substances, including compounds,
would not be stable if the component atoms could, with
continued friction, be eroded. He also preserved from
traditional atomism the absolute mathematical charac-
ter of space and extended it to time, but he made space
and time something more than geometrically ordered
non-being by conceiving space as the “sensorium of
God.” Increasingly he also came to think that space
could not be merely “void” but was filled with a fluid
“aether”—to convey radiant heat, to account for the
optical phenomena of reflection and refraction, to
transmit light corpuscles, and perhaps to help explain
gravitation. His major departure from ancient atomism
(and from Descartes), however, was his rejection of the
concept of matter as essentially geometrical and inert.
First in gravitational theory, then in his speculations
on the nature of matter in the appendix to his
Opticks,
he concluded that matter must be held together by
various and variously intense attractive and repulsive
forces.
To a considerable number of the more enthusiastic
mechanical philosophers, followers, for example, of
Descartes or Thomas Hobbes, the invocation of attrac-
tions and repulsions acting “at a distance” without
immediate bodily contact, entanglement, or impact
seemed a retreat to unintelligible explanation by “oc-
cult qualities.” Although he did in fact “feign hypothe-
ses” to account for some forces, Newton never did so
without simultaneously assuming others. (Thus he
wondered whether his postulated fluid aether might
not account for gravitation through pressure by being
more rare in the vicinity of solid bodies, but accounted
for that distribution of aether by a mutual affinity of
its parts.) His main reply to objections was that these
assumptions enabled one to account for such phe-
nomena as gravitation, magnetism, electricity, the
varying stabilities and combining properties of chemi-
cal substances, deliquescence, internal cohesion of ma-
terial particles, and capillary action, and that he was
more concerned with fidelity to the undoubted fact
than with the transparent intelligibility of the explana-
tion—a reply which, incidentally, helps us better to
understand the philosophical point involved in the
controversy over “occult qualities.” Molière was quite
right to ridicule as an explanation (e.g., a “dormitive
faculty” in the case of sleep) something that might
possibly function (as it generally seemed to Aristotle)
as a cautious and minimal registry of fact, whether or
not further causal analysis were possible. If Newton
perhaps avoided dogmatism by reason of his willingness
to admit active potentialities the mechanics of which
he did not purport to understand, it needs also to be
added that he avoided obscurantism by his patience
and resource to measure, calculate, and verify. Toulmin
and Goodfield say that in his synthesis he combined
“the atoms of Democritus into coherent order by ten-
sions and forces like those of the Stoics” (The Architec-
ture of Matter).
