For a moment assume that descartes’ argument works in proving god’s existence, does the ultimate conclusion follow as stated in
premise 6? can descartes be certain that god would not allow an evil demon or computer to systematically deceive humanity? maybe god has a reason, or needs to teach humanity a lesson.
Descartes cannot be certain that God would not allow an evil demon or computer to systematically deceive humanity. But he believes that God is a more sensible being and formal compared to all of us that he created. He believes that God has a reason for everything because he knows everything.