The René Descartes Project
THE PROJECT: To provide the foundation necessary for all the sciences without depending upon Church authority.
Descartes writes his Meditations in 1641 in an attempt to provide a foundation for knowledge which cannot be doubted. This foundation must be palatable both to the Church (hence his endeavor to prove the existence of God and the soul) and the Renaissance approach to the natural sciences (hence his endeavor to avoid grounding his views in Scripture or Church authority).
First Meditation: Descartes begins his meditations by setting his course to finding the thing or things he cannot doubt. In order to find this, he begins a session of frenzied doubting. Empirical data is doubted because Descartes, at any given moment, cannot be sure that he isn't dreaming. Mathematical truths are doubted by following these easy steps: 1) God is free to make mathematical laws appear any way He wants. 2) In order for God to be good, He must make the way math appears to work actually match up with the way math does work. 3) Although God is true and good, there may be an evil demon who comes on the scene whose mission in life is to deceive Descartes (Editor's Note: This hypothesis gains more plausibility the more one thinks about what made Descartes write this stuff.) and twists even his ability to correctly understand math. In this way, Descartes feels he has eliminated our senses and our deductive reasoning as sure foundations for knowledge.
Second Meditation: Descartes decides that, even if he doubts everything, including the existence of his body, the only thing he cannot doubt is that he is doubting. This leads to the famous Cogito Ergo Sum or, if you've somehow managed to ignore anything that anyone has ever said to you at any time about Descartes, "I think; therefore, I am." This, to Descartes, is the first and primary clear and distinct "perception." He uses some freakish wax illustration to prove that, although he does have clear and distinct perceptions about things, those perceptions can only come from reason, not sensory perception. He decides that whatever he can perceive clearly and distinctly - taking his cue from the Cogito - must be true. Clear and distinct ideas offer Descartes a glimmer of hope as far as reconstructing truth and the sciences. There's just one problem...
Third Meditation: A deceiver may be giving Descartes false clear and distinct perceptions. Descartes needs God and fast! He begins to sort through his consciousness to see if he has any clear and distinct perceptions that could not have come from himself. He annoys the reader with a three-fold distinction to reality: formal reality (a vase), objective reality (the vase which exists in your idea of a vase), and material reality (the thought which allows you to compose the idea of the vase). These are annoying distinctions because none of the terms seem to match up with their definitions. In any case, Descartes puts these blocks together and builds the Principle of Causality which says that any idea you have comes from a cause which has at least as much formal reality as there is objective reality contained in the idea. The much quicker version of this is, if you have an idea of something, whatever caused that idea has to be greater (be "realer") that whatever you are conceiving of. Now, René think's he's great enough to have come up with most of his ideas, but his idea of God is of a being so perfect, Descartes could not have come up with it, himself (he's not as great as the being he conceives). Therefore, because of the Principle of Causality, God must exist because He must be at least as real as Descartes' conception of Him. Now, since God exists, Descartes can depend on his clear and distinct ideas, since a perfectly good God would not deceive him or permit him to operate under a totally false conception of the world.
The fact that the proof for God's existence depends on Descartes having a clear and distinct idea of Him, but the validity of Descartes' clear and distinct ideas depends on God's existence, is known as The Cartesian Circle.
Did you hear that giant, sucking sound? That's the sound of all the obstacles in Descartes' epistemology being drained away to Mexico or wherever. Armed with clear and distinct ideas, there's almost nothing Descartes can't establish as true.
Fourth Meditation: If we accept this ball of wax, how do we account for error? Descartes asserts that error requires both an activity of judgment (reason) and will. Descartes' judgment is perfect (in his judgment), but his will may be overextended beyond his judgment's capacities, since reason is finite, but the will is infinite. Therefore, all error is the result of sin, or using the will beyond the capactities of reason. If this needs more explanation to be convincing, it's your tough luck, because none is forthcoming from Descartes.
Fifth Meditation: Perhaps realizing that his first attempt to prove God's existence is a demonstration in logical fallacy, Descartes gives it another go. He cannot conceive of God without conceiving of God's necessary existence. He can think of many things that don't have to exist, but God must exist necessarily in Descartes' idea, or He isn't God. So, we arrive at the existence of God sort of by definition: you can't think of God without necessary existence because God, in order to be God, would have to exist. Toward the end of this Meditation, René opens up a little bit and reveals that he pretty much stakes his knowledge on God's existence, because the building blocks of thought (clear and distinct ideas) depend on a good God who won't steer him wrong in those matters. He, then, snaps out of his pensiveness and orders a round of clear and distinct ideas for everyone reading him.
Sixth Meditation: Descartes still needs to retrieve the external world. Remember the external world? Descartes needs to retrieve it. Well, wouldn't you know it? Descartes has a clear and distinct idea of the external world! Problem solved. However, he wants to prove that the body exists and that his soul (or self or mind) and that they are two different things. Remember, we proved that Descartes has a mind (more specifically, he is a mind) back in the Second Meditation. First, he draws a distinction between imagination and understanding, which basically boils down to the fact that he can understand things without imagining them. Second, he shows that imagination is not a property of the mind alone because, without imagination, he would basically remain the same Self he ever was. Thus, in order to understand, the mind only needs itself. To imagine, however, the mind engages something else. What is it engaging? It has to be the body. Recognizing that this is pretty iffy, Descartes whips out clear and distinct ideas and establishes the validity of sensory perceptions and the existence of his body.
For all the problems, here, Descartes' influence in philosophy cannot be underestimated. The epistemic foundation, presuppositionless systems, the mind/body problem, and the subject/object relationship are issues that haunt philosophy to the present day. In one, fell swoop, Descartes split apart you and the external world. Much of later philosophy is spent trying to get these two together, somehow. Not to mention, all that stuff about natural light, God being a substance, and axioms makes its way into the Westminster Confession of Faith, somehow. Probably that evil demon thing...