No More Learning

But it is hard to understand how we could know some- thing without knowing what its absence entails: and it may well be, as Colin McGinn argues, that consciousness is one of those           problems which human be- ings are structurally unfit to solve; and that in that sense Kant's was the right posi- tion to take: that, although its existence is as certain as the Cartesian cogito, con- sciousness must also remain perpetually unknowable as a thing-in-itself.