The one thing that Descartes cannot doubt is that
A) he exists.
B) an evil genius exists.
C) the external world exists.
D) he has a physical body.

Question

Quizplus · Accepted Answer

Descartes concludes that he cannot doubt his own existence because the very act of doubting confirms that there is a thinking entity - summed up in his famous dictum, "Cogito, ergo sum" ("I think, therefore I am").

The One Thing That Descartes Cannot Doubt Is That