(^108) › STEP 4. Review the Knowledge You Need to Score High
relocated to the Netherlands, where he published (in 1637) a challenge to both the
authority of scholasticism and to the validity of the Galilean approach. In Discourse on
Method, Descartes began by sweeping away all previous claims to knowledge by skepti-
cally asserting that “received knowledge”—that is, information that you do not learn
for yourself—amounted to nothing more than “opinion.” But rather than proceed from
observation, Descartes extended his skepticism to the senses, which, he asserted, could
easily be fooled; instead, he sought the “clear and distinct idea”—that is, one that could
not reasonably be doubted.
The first idea that Descartes could not doubt was that he was thinking, and that if he
was thinking, then he must really exist. From that famous formulation—“I think, there-
fore I am”—Descartes proceeded to deduce a variety of truths, including the existence of
God and a cosmos made up of only two things: matter and motion. Putting the sun in the
center (as Copernicus had done), Descartes described a solar system in which the planets
were simply large chunks of matter that were caught in swirling vortices of smaller matter.
This Cartesian approach of deducing the details of nature from a set of clearly defined gen-
eral propositions appealed to those who sought an intelligible explanation of the cosmos,
rather than the mathematical calculations of the Platonic–Pythagorean tradition.
The Enlightenment
“The Enlightenment” refers to an eighteenth-century cultural movement whose propo-
nents argued that society and its laws should be based on human reason, rather than on
custom, religion, or tradition. Its roots can be traced to the late seventeenth century, when
thinkers and writers began praising the method of inquiry and the accomplishments of Sir
Isaac Newton. Following Newton, political writers like John Locke began suggesting that
there were natural laws that govern human behavior and that these laws could be discovered
through reason. In the eighteenth century, intellectuals known as philosophes developed
a program for reforming society along the lines of reason, which they initially hoped to
implement by educating the powerful rulers, or “enlightened despots,” of Europe. Later
in the century, when enlightened despotism seemed to have failed, Enlightenment ideals
began to be applied in more revolutionary contexts.The Triumph of Newtonian Science
Isaac Newton was an Englishmen who was educated at Cambridge University at a time
when its faculty was committed to the advancement of Neoplatonism and to the rejec-
tion of Cartesianism. As a fellow of Trinity College, Cambridge, Newton lived a solitary
life and was driven by the notion that God had left clues to His true nature in the laws
that governed the natural world. Newton was intensely focused on solving the mystery
of planetary motion. Using a mathematical system of his own creation, which he called
“fluxions” (and which we now refer to as calculus), and following Kepler’s suggestion that
the paths of planetary orbits were elliptical, Newton was able to calculate the orbits of the
planets precisely by assuming that each particle of matter, no matter how large or small,
was drawn to every other piece of matter by a force that he called universal gravitation.
Newton published his results in 1687 in his great work, the Principia Mathematica
(The Mathematical Principles of Natural Philosophy), in which he stated, “Every particle
of matter in the universe attracts every other particle with a force varying inversely as theKEY IDEA15_Bartolini_Ch15_099-118.indd 108 27/04/18 1:54 PM