While Kant arguably manages to show in section 65 of the Critique of Pure Reason (“Refutation of Idealism”) that the concept of a self existing through time cannot be reconciled with skepticism of the external world, does this really refute Cartesian epistemology?
The problem is that the existence of one’s consciousness in the immediate present seems to evade Kant’s criticism. Here no appeal to an objective order in time of inner states is necessary. Isn’t this enough for Descartes to reach his further conclusions?