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that, in the end, may overthrow the foundations of all philosophy. For causes
generally proceed in a continuous chain from compound to more simple;
when you reach the simplest cause, you will not be able to proceed any
further. Therefore no mechanical explanation can be given for the simplest
cause; for if it could, the cause would not yet be the simplest. Will you ac-
cordingly call the simplest causes occult, and banish them? But at the same
time the causes most immediately depending on them, and the causes that
in turn depend on these causes, will also be banished, until philosophy is
emptied and thoroughly purged of all causes.^34In effect, Newton’s means of dealing with the distinction between
causal physics and descriptive mathematics was to analyze the concept
of cause that supposedly stood between them. His argument, as refracted
here through his spokesman, Cotes, was that a proper understanding of
physical causation shows that any and all causal analyses will ultimately
terminate in primitive items that cannot be further reduced—if not gravi-
tational attraction, then something else prior on the causal chain, but
there will always be something that cannot be further explained in terms
of something simpler. So if his critics held that he was not dealing in real
causes by stopping at gravitational attraction, his reply was that any such
analysis will end that way; they themselves would therefore be open to
analogous criticisms of any of their own explanations. The point was sim-
ply a variation on the well- known account in Aristotle’s Posterior Analytics
of deductive demonstrations: all must begin from starting principles that
cannot themselves be proven, or an infi nite regress would result.^35
Newton could make the shift from logical to causal analysis because
his model of causation was no longer that of the Aristotelians, whose
four causes—formal, fi nal, effi cient, and material—usually possessed a
self- suffi ciency that rendered them immune to regress arguments. For ex-
ample, a formal- cause argument such as “Socrates is mortal because he
is a man” took its validity from the supposed self- evidence of Socrates’
humanity, as well as the implicit defi nitional property of mortality pos-
sessed by men. By contrast, Newton’s type of causation was that of those
he called “the moderns,” by which term he referred to ontological mecha-
nists in the Cartesian tradition, including most notably Huygens himself.
If their kind of mechanical causation was the only physical causation
permissible in natural philosophy, then Newton’s response to their criti-
cisms of him could undercut the claimed irregularity of his own work.^36
Mechanistic physics, in other words, had already taken the crucial steps in
redefi ning causation in a way that now permitted Newton’s experimental
philosophy, with its mixed mathematical procedures, to be represented as