is a
Latin philosophical proposition by usually translated into English as "
I think, therefore I am". The phrase originally appeared in
French as in his
Discourse on the Method, so as to reach a wider audience than Latin would have allowed. It appeared in Latin in his later
Principles of Philosophy. As Descartes explained, "[W]e cannot doubt of our existence while we doubt … ." A fuller form, ("I doubt, therefore I think, therefore I am”), aptly captures Descartes’ intent.