An Epistemological Nightmare

(by Raymond M. Smullyan, 1982)

"Scene 1

Frank is in the office of an eye doctor. The doctor holds up a book and asks "What color is it?" Frank answers, "Red." The doctor says, "Aha, just as I thought! Your whole color mechanism has gone out of kilter. But fortunately your condition is curable, and I will have you in perfect shape in a couple of weeks."

Scene 2

(A few weeks later.) Frank is in a laboratory in the home of an experimental epistemologist. (You will soon find out what that means!) The epistemologist holds up a book and also asks, "What color is this book?" Now, Frank has been earlier dismissed by the eye doctor as "cured." However, he is now of a very analytical and cautious temperament, and will not make any statement that can possibly be refuted. So Frank answers, "It seems red to me."

Epistemologist:
Wrong!

Frank:
I don't think you heard what I said. I merely said that it seems red to me.

Epistemologist:
I heard you, and you were wrong.

Frank:
Let me get this clear; did you mean that I was wrong that this book is red, or that I was wrong that it seems red to me?

Epistemologist:
I obviously couldn't have meant that you were wrong in that it is red, since you did not say that it is red. All you said was that it seems red to you, and it is this statement which is wrong.

Frank:
But you can't say that the statement "It seems red to me" is wrong.

Epistemologist:
If I can't say it, how come I did?

Frank:
I mean you can't mean it.

Epistemologist:
Why not?

Frank:
But surely I know what color the book seems to me!

Epistemologist:
Again you are wrong."

Read the rest here.