Great Ideas of Philosophy

1. This standard essentially rules out the objects of perception.2. Perceptions and feelings aside, there is another activity of the soul—thinking.III. “I think, therefore I am,” Descartes’s well-known but misunderstood “proof” of his existence, is actually asummary of the grounds on which he would base all valid knowledge claims.A. Descartes began by assuming that one cannot say, with epistemic authority, that one is an extended thing, ares extensa, because descriptions about actions one takes or physical characteristics clearly could besubject to self-deception or deception by a malignant demon.1. One might never be able to distinguish between reality and a dreamed reality.2. All empirical modes of verification are vulnerable to the same demonic deception.3. Nothing external to the mind, as such, will count against this demon theory.B. The one thing that clearly is inseparably bound up with the reality of one’s being is thought. In this, onecannot be deceived, because it is only insofar as an individual is a thinking thing that he or she is subject todeception.C. This is the point of cogito ergo sum. It is not a device that Descartes needs in order to deduce his existence.What Descartes searches for is the necessary precondition for skepticism, which turns out to be thoughtitself or, more generally, the reality of the mental, which is affirmed even in the act of doubting it.IV. Descartes arrived at his discovery through a form of rational analysis, a kind of axiomatic method, not unlikewhat one finds in mathematics and geometry, which is outlined in his Discourse on Method. There are fourmain points set forth in the work:A. Accept nothing as true except what presents itself with a clarity and vividness that is irresistible.B. Divide each problem into as many smaller steps as possible.C. Work from the solution of the smallest problem to the solution of problems of greater complexity.D. Test the general solution with persistence, assuring yourself that it suffers from no exceptions.V. Fortified with a method of inquiry, Descartes would turn his attention productively to what comes down to usas philosophy of mind, the nature of the relationship between a res cogitans and a res extensa. What can anextended thing and a thinking thing have in common? If they have nothing in common, how can one influenceor in any way interact with the other?A. In sharply distinguishing between the res extensa and the res cogitans, Descartes gave the fullest modernexpression to the mind/body problem, either not appreciated by earlier philosophers or not directlyaddressed by them.1. How can a material body cause the mind to think?2. How can an unextended immaterial mind cause a material body to move?B. Descartes’s perceptual and motivational theories are unabashedly physiological.1. Fine fluids or spirits move in the body to bring about motion hydraulically. The mind can, in somefashion, move the body— this can be proved by lifting your arm.2. The physics of motion can account for rudimentary sensory-motor functions but cannot be the cause ofdefinitive mental events and the purely abstract features of mental life.C. Descartes offers a thought experiment our age would describe as one involving artificial intelligence:Given that so much of our behavior and perception are easily explained mechanistically, might we be ableto make a device indistinguishable from a human being?1. Such a device would never attain the idea of God.2. It would never be able to traffic in abstract reasoning, such as is common in mathematics.3. It would never be able to use language in a creatively discursive fashion.VI. Descartes is famous (and infamous) for espousing “innate ideas,” over which even his contemporaries arguedwith him. According to his theory, some things that are obviously and universally known, and could notpossibly be known as a result of experience, can be accounted for only on the basis of the existence of someinnate, or intuitive, rational power.A. In countering a caricature version of his thought, Descartes explicitly denies in print that he eversubscribed to such a notion.©2004 The Teaching Company Limited Partnership 5