Kant’s ideas are so counterintuitive that they produce an almost visceral resistance. The notion that reality might be completely different from how it presents itself to us seems absurd, unreal, and impossible to take seriously. We resist Kant emotionally, no matter how compelling his argument. Normally reasonable people like Dennett respond to Kant with evident impatience. They are unable to answer his argument, but they pretend that it is not necessary to answer it. This attitude may be termed the “fundamentalism” of reason. It is reason so sure of itself that it refuses to consider reasonable criticism. Reason has become irrational and now relies entirely on simple intuition or “common sense.”
Common sense, however, is not always a reliable guide to the truth. Common sense tells us that the earth is stationary and that the sun goes around it. Common sense tells us that an object is naturally at rest and that a moving object must automatically come to a stop. Common sense tells us that space and time are absolute. All these simple intuitions are false. In fact, the great discoveries of modern science—from Copernicus to Galileo to Newton to Einstein to Bohr to Heisenberg—are all massive violations of common sense. That is why in several cases the geniuses who first put forward those ideas were dismissed as crackpots. We now know that these crackpots were right. So it is a fact, not a matter of opinion, that reality is sometimes very strange and that common sense does not give us an unfailingly accurate picture of the world. To proclaim that it always does is to expose oneself as an ignoramus. Common sense, philosopher Bertrand Russell once said, is the”metaphysics of savages.”
Kant recognized that he was producing a revolution in human understanding. Just as Copernicus had turned the world “upside down” and forever altered the way we perceive the earth in relation to the sun, so Kant considered his own philosophy as producing a kind of Copernican revolution in thought. Of course people will still continue to perceive the world pretty much in realist terms—just as we go about our daily lives without worrying about the fact that we live on a planet hurtling through space at many thousands of miles per hour— but even so, this realism has been exposed as an illusion.
