“This most beautiful system of the sun,
planets and comets, could only proceed from the counsel and dominion of an intelligent
and powerful Being.”
(Isaac Newton)
A mathematician and
physicist, Sir Isaac Newton (1642-1727) produced work – philosophical to a
degree – which served mainly as an impetus and basis for many of the
philosophers of his and succeeding generations, including John Locke and
Immanuel Kant, who both owed much to him. Newton’s principal work, the Philosophiae Naturalis Principia Mathematica
contains his theory of gravity and laws of motion. His later work, the Opticks, is primarily concerned with
optical physics but also contains speculations on mechanics, religion and
morals. He was to be involved in a series of disagreements with Gottfried von
Leibniz, initially over which of them was the first to invent the calculus, and
later over the issue of the status of space and time.
The insight behind Newton’s
physics was that the universe runs according to law-governed mechanical
principles. This idea was to have a profound influence on John Locke, whose
philosophy may be seen as the philosophical working out of Newton’s physical
principles. Locke was determined to make sense of human understanding in a way
consistent with Newtonian mechanics. As a result, he argued for a causal theory
of perception and for a distinction between primary and secondary qualities of
objects.
Emmanuel Kant, in similar
fashion, recognized that everything in the phenomenal world had to conform to
Newton’s principles, but that this order was for the most part imposed by the psychological
apparatus of the mind. Kant’s philosophy gave support to Newton in the quarrel
with Leibniz over whether space and time should be conceived of as absolute or
merely as relations between objects. The debate seemed to have been won hands
down by the Newtonians until the advent of Einstein’s relativistic physics.
Claiming that his method
was empirical and inductive, rather than rationalist and deductive, Newton was
also fond of criticizing Rene Descartes. It is thanks to Newton that empiricism
began to enjoy a period of dominance over rationalist philosophy. However,
Newton owed much to Descartes’ thought, and it is likely his own speculations
could not have begun but for the work already undertaken by his rationalist
predecessor.
Undoubtedly, Newton’s
greatest achievement was his theory of gravity, from which he was able to
explain the motions of all the planets, including the moon. Newton proved that
every planet in the solar system at all times accelerates towards the sun. The
acceleration of a body toward the sun is at a rate inversely proportional to
the square of its distance from it. This led to Newton’s law of universal
gravity: “every body attracts every other
with a force directly proportional to the product of their masses and inversely
proportional to the square of the distance between them.” The law of
universal gravity allowed Newton to predict all of the planetary motions, the
tides, the movements of the moon and of the comets.
It was a striking
achievement that would not be superseded until Albert Einstein, although even
with the advent of Einsteinian relativity, Newton’s mechanics still holds good
– and indeed is still used, on account of its simplicity, for predicting the
movement of so-called ‘medium-sized’ objects – anything that is neither bigger
than the solar system nor smaller than the eye can see. Newton’s work is
profound and remarkable achievement in the history of human thought.
[Summarized from Philosophy 100 Essential Thinkers by
Philip Stokes, 2012.]
Lord, Give
Us Today Our Daily Idea(s)
