How does a materialist account for the stubborn fact of consciousness? If it’s nothing but physical brain activity, then what is my consciousness of my physical brain activity? Remember, the knowledge of a thing one of the parts of the thing known. This can be proved by formal logic alone. For the alternative would make accurate knowledge (knowledge that matches the thing known) impossible. For in the very act of knowing all the facts about a thing you create a new fact about that thing: that it was known. And that fact can be only known still by another act of knowing, et cetera ad infinitum.
--Peter Kreeft, Letters to an Atheist, 2014