His skepticism was methodological, his goal was indubitable certainty. This, he thought, would serve the new science well. He misunderstood the self-correcting, probabilistic, fallibilistic nature of empirical reasoning. But most philosophers still think it’s worth wondering: how do you know you’re not dreaming, not being deceived by a demon or by your senses, not mistaking your own essential nature?
Still, cogito ergo sum overrates intellect. You don’t have to think, to demonstrate your existence. You just have to do something… even, as an old grad school pal used to say, if it’s wrong. (NOTE TO CLASS: I flip-flopped Descartes and his predecessor Montaigne, the anti-Descartes, on our syllabus: Descartes before the horse M. fell off of.)
Descartes' different aspects - mathematician, scientist, Catholic etc. - might suggest his split allegiance between Teams Aristotle and Plato. Both would probably like to claim him. I think he belongs with the armchair Platonists.
Reducing the operations of the universe to a series of lines,circles, numbers, and equations suited his reclusive personality. His most famous saying, “I think, therefore Iam” (cogito, ergo sum), could be stated less succinctly but more accurately as 'Because we are the only beings who do math, we rule.'
For Descartes, the essence of mind is to think, and the essence of matter is to exist-and the two never meet... we are the ghosts in the machine: souls in a world machine that operates inexorably and impersonally according to the laws of geometry and mechanics, while we operate the levers and spin the dials." The Cave and the Light
I usually think of Charles Sanders Peirce as Descartes’ most practical critic, and I agree with him that a contrived and methodological doubt is not the best starting place in philosophy.
But it occurs to me that an even more practical alternative to what I consider the misguided Cartesian quest for certainty is old Ben Franklin’s Poore Richard. His is not armchair wisdom, it comes straight from the accumulated experience of the folk. Some of that “common sense” is too common, but plenty is dead-on. “Early to bed, early to rise…” has definitely worked for me.
Still, says A.C. Grayling, "we may disagree with Descartes that the right place to start is with the private data of consciousness" rather than the shared world of language and common experience; but even if he was wrong he was "powerfully, interestingly, and importantly wrong." Russell concurs.
The thing is, the quest for certainty in philosophy tends to go hand-in-glove with the assertion of rational necessity. That, in turn, courts determinism and fatalism. Do we really want to rubber-stamp everything that happens as fated, not free? Hobbes (the contractarian and the cat) did. Calvin learned not to.
Is there anything we know or believe that we could not possibly be mistaken about, or cannot reasonably doubt? Certainly not, speaking at least for myself. But I'm next to certain that I'm more-or-less awake, at this hour, as the coffee drains.
I'm also pretty darn sure that I am (and do not "have") a body/brain. When I think of who, what, and where I am, though, the answer is interestingly complicated by all my relations (I don't just mean my familial relations): I am inclusive of a past and a future (though it keeps shrinking), and of wherever my influence (for better or worse) manages to stretch. I am vitally related by experience (actual, virtual, vicarious, possible, personal, interpersonal) to points far and wide. And, to actual physical objects in the extended world - not merely to possibilities of familiar object-like patterns of perception, as the phenomenalist has it. I'm not trapped in my skin, and we are definitely not alone in a solipsistic universe. Like Dr. Johnson, contra Berkeley, I find the pain in my toes (or hips) decidedly more substantial than an immaterial idea.
I don't believe in ghosts, except metaphorically. (I am haunted by opportunities missed, possibilities unnnoticed, diems uncarped.) But most of my metaphorical spooks are Casperishly friendly (albeit incoherent, dualistically speaking). This is true of most people who read and think a lot, isn't it? We're in constant, happy communion with the dead, the remote, and the prospective members of our continuous human community. Books transport us to their realms, and to the great undiscovered country of our future.