Philosophy

In the second meditation, he appears to define thinking in terms of all conscious acts when he describes a thing that thinks as "a thing that doubts, understands, affirms, denies, is willing, is unwilling and also imagines and has sensory perceptions". Williams makes the point that the translation of the Latin verb "cogitare" and the French verb "penser" have wider meaning than the English "to think". They relate to any conscious state or activity. However, if Descartes" definition of thought was really this broad it would need to be possible to assert that having sensory perceptions was indubitable as the ability to think. However, as he asserts in the first meditation, it is not the case to believe that "I have sensory perceptions" necessarily makes it a true belief. Despite this difficulty, Descartes" inclusion of, among others, imagination in the above definition of thinking demonstrates that he clearly does not interpret thinking in the narrow sense of being just a cognitive act of the intellectual kind. However, as Cottingham shows, this is partially the fault of categorising the definitions of what it is to think to rigidly. When Descartes says that it is necessary to doubt, understand etc. he is actually referring to the ability to be aware of these rather than being able to control the activities in their own right. Thus the assertion that "I am aware that I have sensory perceptions" is as indubitable as "I am aware that" and is thus equated with "I think". Williams describes this as Descartes" willingness to "sheer off " purely mental experience. Thus the conclusion can be reached that "thought" can be defined as "that of which I am immediately aware". .
             To return to the question of how he can be certain that he has a true belief, Williams writes that Descartes" certainty that he thinks is based not just on its incorrigibility, but also on its self verifying nature. If Descartes asserts "I think" then this must be true because the act of thinking the statement, proves it.