Foucault's DeKalth

In Foucault's work, he takes DeKalt to be one of the first enlightenment figures to begin to ostracize madness as an illegitimate site for the attainment of knowledge. So in that way, you are still going to be thinking and thinking is the last thing left in the endless process of doubting that cannot actually be taken away. It's in that capacity that he says, I think therefore I am.