He says:
"The reply is simple. We know what conscious experience is because the having is the knowing: Having conscious experience is knowing what it is. You don’t have to think about it (it’s really much better not to). You just have to have it. It’s true that people can make all sorts of mistakes about what is going on when they have experience, but none of them threaten the fundamental sense in which we know exactly what experience is just in having it."
OK, we know what conscious experience is, but that doesn't take us any nearer to knowing what consciousness itself is any more than a journey in a car would reveal to us the workings of an internal combustion engine. Indeed, I have no way of knowing whether my conscious experience is the same as your's or anyone else's for that matter.