Rene Descartes 1596-1650 Rene Descartes 1596-1650

4. The Evil Deceiver:Descartes believes that he cannot be certain of even his seemingly most certainbeliefs such as the truths of mathematics, for he has found an alternativeexplanation of why he believes them, which he is unable to rule out.Descartes’ ground of doubt for a priori beliefs, namely, the evil deceive, issufficient to cast doubt on all his beliefs.Why did not he not just start off using the evil deceiver as a ground of doubt?The answer: Descartes suspects that, in fact, some of the beliefs he has set asideare true, while others are not.Even if there is not an evil deceiver-and he will show us that there is not, thereare still good reasons for doubting some of our beliefs, such as those based onsense perception. Thus, it is important to be aware of all of the reasons for 48doubting each set of beliefrs.