René Descartes is sometimes called “The Father of Modern Philosophy” because he single-handedly ended 2000 years of bad philosophy. (I’ve put some bad philosophy in later.) Astonishingly, Descartes was not only the world’s greatest philosopher, he was also the world’s greatest mathematician. Cartesian geometry (the geometry of the game “Battleship”) is named for him.
In the following passage from Meditations on First Philosophy, Descartes is trying to end the problem of skepticism Putnam discussed above. The problem of skepticism is this: once we start doubting, it is hard to stop.
I’ll give you stupid example: I used to study in bed. Philosophy is boring, so I fell asleep a lot with a book on my chest. Oddly, I often found myself dreaming about reading philosophy—I would transition very smoothly from awake to asleep, and I wouldn’t even notice. I would appear to myself to still be doing homework, even though I was asleep.
Now, I am awake, sitting in front of the computer. But that smooth transition makes me worry a lot: there were those times I did not notice falling asleep. So how do I know that I’m not asleep right now, in front of the computer? Maybe I just slipped out there for a minute.
But if I am asleep now, how do I know I’ve ever even been awake! Maybe everything is a dream! Maybe nothing is real!
This is the problem of skepticism: doubt snowballs. A small moment of skepticism leads to a big issue.
Descartes wants to stop the snowballing. His method is amazing. He uses judo: he takes the force of the problem and turns it to his advantage. He says, roughly, that instead of being forced to test everything he knows to see if it is indubitable, he will try to doubt everything, and see what remains. Instead of fighting the problem, he flips it around. Juuudo!
Of course, Descartes is doing epistemology. He is trying to answer the question: What do we know for certain? His answer is astonishing. It’s brilliant. It’s amazing. It is so amazing, that you will have heard of it—but it means something totally different from what you think it does. I won’t spoil the surprise.
Descartes died of sleep deprivation. Or he was poisoned by the Pope. Seriously. The French tore his corpse apart to save for souvenirs. Or should I say, souven-ears!
