Descartes asks the following: "How do I know that I am not also deceived each time I add together two and three"? Furthermore, "If, however, it were repugnant to the goodness of God to have created me subject to constant deception, it would seem likewise to be contrary to his goodness to allow me to be occasionally deceived; and yet it is clear that this is permitted." From this Descartes concludes that "there is nothing of all that I formerly believed to be true of which it is impossible to doubt."

Question

Quizplus · Accepted Answer

Descartes argues that because he cannot be sure he is not being deceived, he cannot know anything for certain. He also argues that if God exists and is good, it would be incompatible with his goodness to allow for deception, but since deception happens, it must be that there is nothing he can know for certain. Therefore, he concludes that he must doubt everything he formerly believed to be true.

Descartes Asks the Following: "How Do I Know That I