To this objection Derrida replies in advance: the risk of madness is indeed well and truly confronted by Descartes, not as you claim in a prior and almost marginal manner, regarding some business with water jugs and naked kings, but at the very heart of his philosophical enterprise; there precisely where his discourse, wrenching itself away from natural considerations about errors of the senses or swellings of the brain, takes, in the hyperbolic doubt and the hypothesis of the evil genius, its most radical dimension.