. In his First, Second, and Sixth Meditations, Descartes outlines and carries out part of his plan in search of the indubitable. With the proposal of an "evil genius" and the noted fallibility of the senses, he casts potential doubt on virtually all fundamental knowledge (Meditation I). Then he proposes that the only knowable fundamental truth is the fact that "I" exist (Meditation II). Finally, after systematically building up higher- level indubitable truths from that fundamental, he details the differences and interactions between the mind ....