Rene Descartes (1596-1650) was a French mathematician of considerable powers, but his talents went further than that. Rene Descartes is to modern philosophy what Plato is to ancient philosophy, and what Aquinas is to the philosophy of the middle ages—that is, its founding father. From his youth, Descartes was obsessed with math and science. It dominated him; he would rather think about math and science than play outside. He would rather think about math and science than play soldier with the neighbor boys—for Descartes was unusual and talented indeed. He would rather think about math and science than play soldier with the neighbor boys, but when he came to manhood he actually joined the Dutch army—in order to have more time to think, he said! And think he did. He traveled around Europe thinking; he fathered a child, a daughter, who died very young, and broke his heart. He returned to France and devoted himself to philosophy. He began writing books in secret.
Descartes, more than anything else, was interested in unifying science into one great organized schemata, into a system; he wanted to impose order on the disunity of science. But to do that, he must find some grounding principle first. Descartes is the founding father of modern philosophy because he was the first to create a system—a philosophical system, that is, a system that encompassed all areas of knowledge and wisdom, including math and science, including even theology—in the modern style. The modern style of creating philosophical systems is to do it on your own.
In ancient philosophy, but especially in the philosophy of the middle ages, the system, while filled with enormous, important personalities to be sure, was nevertheless more like a web cast out, out, out across the west and deeply into the east. (We owe our Aristotelian inheritance largely thanks to the astonishing efforts of medieval Islamic philosophers, for example, who preserved and handed down Aristotle’s texts when they had been all but lost to their native lands.) I.e., it was “the” system, not “a” system. You had enormous personalities to be sure, but still they were joined together as it were with a web, with each building on the efforts of each, or at least borrowing heavily from one another; ancient and medieval philosophy have very much a family feel to them, while modern philosophy is about renegades, lone wolves.
Modern philosophy is the story of lone wolves creating philosophical systems, seemingly, out of nothing; when you think of modern philosophers, you think of them singly—Descartes, Hegel, Kant, Newton, Pascal, James, Kierkegaard, Wittgenstein—you think of these lonely figures spinning out webs of systems, but in the privacy of their library. Of course, modern philosophers relied heavily on the past and on each other. Still, though, it can’t be denied that modern philosophy (as well as much of modernity in general) has a certain loneliness to it. Descartes wanted to build a system that would unify philosophy, and said that he must first have a groundwork, a foundation. His essential question was, what can I build my system on? What am I sure of enough that I can construct an entire philosophical system on it?
Well, everyone, probably, has heard the famous summation of the answer to this question—when at last it came. “I think, therefore I am”—that’s Rene Descartes! He set out and ruthlessly began to doubt everything he was certain of; everything. Love, the natural world, the body—he doubted it all. And he found, in the end, that what he was left with was—his mind. His mind was the one thing he knew, the one thing he controlled with almost absolute power; he couldn’t helpt getting a toothache, he couldn’t helpt it if his knees ached! But his mind, there was the seat of power. And he proceeded to build his system from there, a system, to be sure, that would be knocked about and shaken and tried and examined from every angle in his day, just as it is in our own. Probably today it wouldn’t be a good idea to join the army for a little peace and quiet, for a little thinking time. But perhaps next time you hear or read “I think, therefore I am”—perhaps you’ll think of Descartes in his handsome Dutch uniform, and you’ll know that you are. That is, you’ll know you exist, because you’re thinking! Three cheers!