1 The Birth of Science - MSRI

336 11. The Age-Long Recovery
Newton is often considered the founder of physics in the modern sense
of the term. Indeed, although his Philosophiae naturalis Principia mathematica
starts from definitions and axioms, following the practice of ancient
science, it is clearly Newton’s intention to move away from the model of
ancient mathematics. On this point one can do no better than quote Roger
Cotes, the editor of the second edition of the Principia. He writes in the
book’s preface (italics mine):
[Those who possess experimental philosophy] derive the causes of
all things from the most simple principles possible; but then they assume
nothing as a principle, that is not proved by phenomena. They frame
no hypotheses, nor receive them into philosophy otherwise than as questions
whose truth may be disputed. They proceed therefore in a twofold page 412
method, synthetical and analytical. From some select phenomena
they deduce by analysis the forces of Nature and the more simple
laws of forces; and from thence by synthesis show the constitution
of the rest. This is that incomparably best way of philosophizing,
which our renowned author most justly embraced in preference to
the rest[.] 152a
This passage is perfectly emblematic of the birth of modern physics as a
science distinct from ancient mathematics. The ancient scientific method,
which for so many centuries not even those who could not understand
it had dared contradict explicitly, is here haughtily repudiated. Many of
Newton’s own assertions bear witness to the same attitude: the regulae
philosophandi that open Book III of the Principia (particularly the fourth);
the General Scholium that concludes the second edition of the same work
(with the famous sentence “Hypotheses non fingo”: I do not make hypotheses);
and the considerations at the end of the Opticks. 153
Newton’s science, unlike classical natural philosophy, makes systematic
use of instruments that are mathematical in the modern sense of the term.
And yet what he does is physics and no longer mathematics, in the sense
that he rejects hypotheses whose truth cannot be established; he is not
content with a theory able to save the appearances, but instead seeks that
substantial reality, beyond appearances, whose knowledge Simplicius and
Thomas Aquinas, following Aristotle, had placed in the realm of physics.
The word hypothesis, for Newton, had taken on the meaning that is now
most current (and different from the classical one) — something still under
debate, whose truth or falsehood will sooner or later will be definitively
152a Preface to second edition (Cambridge, 1713), at 8%, Motte/Cajori translation.
153 Such as the statement: “For Hypotheses are not to be regarded in experimental Philosophy”,
in Opticks (1704), p. [SL will supply] (or p. 404 in the most common reprints of the 1730 edition).
Revision: 1.11 Date: 2003/01/06 07:48:20