The essential property of a mind is that it thinks; the essential property of body is that it is "extended." Each thought is a modification of mind; each physical object, a modification of matter. Since mind is different from body (otherwise, they would not be two distinct substances), its essential characteristics must be different from those of body. This means that minds cannot take up space or be extended. If they were, they would be forms of body. Body, in contrast to mind, is that which is extended. Every form in which a material object can exist can be defined or described in forms of its extensional features-size, shape, position, movement.
2. Explain how Descartes' method of doubt was supposed to insure certain knowledge. What is the special role of innate ideas in Descartes' theory of knowledge Which ideas did Descartes considered to be innate How are innate ideas different from other types of ideas
Descartes' method of doubt says that he wishes to examine those things which he thinks to be true and set aside all those beliefs of which there might be some doubt.