Abstract

Descartes thought he could suppose he was the victim of massive deception in regard to the external world. In fact he undertakes the supposing of it.I will … suppose that … a certain evil spirit, not less clever and deceitful than powerful, has bent all his efforts to deceiving me. I will think that the sky, the air, the earth, colors, shapes, sounds, and all other external things are nothing but illusions and dreams that he has used to trick my credulity. I will regard myself as having no hands, no eyes, no flesh, no blood, nor any senses, but believing falsely that I have all these things.Seated comfortably by his fire, Descartes imagines a remote possibility. Perhaps he is just a mind in the clutches of a deceiving demon. If Descartes is this man lounging here in his dressing gown, he is not vastly deceived; but if he is that mind, he is deceived indeed. The two possibilities are taken to be experientially indiscernible; and Descartes is assuming that the contents of his beliefs and the senses of his claims remain the same in either case. Thus, for example, whether he is this man or that mind, he believes he has two hands. But, and this is crucial, his belief is false if he is that mind, and true if he is this man. We begin to see what is required of cartesian semantics, and cartesian theories of the content of belief.