French philosopher René Descartes (1596–1650) is often called the Father of Modern Philosophy. He started out his career as a mathematician and is credited with discovering the concept of Analytic Geometry. He also was a physicist of great repute. Descartes was a faithful Catholic, but he privately knew the Church was wrongheaded in its resistance to and persecution of men of science. He knew that these men and their philosophies were the way of the future, and if the Church did not adapt, it would suffer as a result.
Descartes sought nothing less than the formidable task of a radically revisionist look at knowledge. He started with the premise of doubt. He decided to doubt everything. He believed that everything that he knew, or believed he knew, came from his senses, and sensory experience is inherently suspect. This is the classic Skeptic starting point.
Descartes was hesitant to publish much of his work because it supported the findings of Galileo. He eventually “hid” his controversial theories in a philosophy book called
Descartes quickly discovered that to doubt absolutely everything is to be poised on the precipice of madness. Is it real, or is it a dream? Descartes came to believe that he could not even know if he was awake or if he was dreaming things. There is no absolute certainty, not even in the realm of mathematics. This was called the Dream Hypothesis and is radical skepticism taken to the max.
Descartes went on to speculate that there might not be an all-loving God orchestrating things from a celestial perch. Perhaps there was an Evil Demon who had brainwashed us into believing that all we see and sense is reality, but is really an illusion devised by this diabolical entity. This is called the Demon Hypothesis.
Cogito, Ergo Sum
You have heard the Latin phrase “Cogito, ergo sum” in its English translation. It is perhaps the most famous sentence in the history of philosophy. “I think, therefore I am,” became the rallying cry of the modern philosophical age.
Everything could be questioned, but one thing remained a fact: the thinking of the thinker. Self-awareness. You can count on at least one thing in this wacky world, according to Descartes: Wherever you go, there you are.
Descartes then tried to use this newfound certainty to prove the existence of God. It is an ontological argument similar to the one employed by St. Anselm a few centuries earlier. Descartes used the following arguments to “prove” the existence of God:
“‘I think, therefore I am’ proves that I exist, but I am an imperfect, flawed mortal man. If I were my own creator, naturally I would have made myself perfect. This proves that I did not create myself, and if I did not, than who did? God.”
“I have a conception of what perfection is, though I am not perfect. Okay, so where does this idea of perfection come from? Not from me, of course. After all, I'm imperfect, and perfection cannot come from something as so patently imperfect as I. So there must be a perfect being, and that is God.”
Having proved that he existed and having “proved” the existence of God, at least to his satisfaction, Descartes turned his sights on the nature of reality. According to Descartes, two elements compose reality, as we know it. He called them substances.
Though a scientist and mathematician, Descartes sounds like St. Paul when he speaks of the body-mind disconnection, or
Descartes was a Rationalist, meaning that he believed that you can know things without having to rely on sense experience. These are called innate ideas, or primary ideas. Other information gathered from experience is called secondary.
Descartes was initially hesitant to publish his theories because they strongly resembled those of Galileo, and he did not want Torquemada, the Grand Inquisitor, knocking on his door. But he ultimately did so and further shook the foundations of the Church, which was reeling from the one-two punch of the Protestant Reformation and the Scientific Revolution.