No replies (regarding the thread topic) yet? Perhaps Smullyan's allegory is too long. Let's try an excerpt so you don't have to read the whole thing:
The main philosophical problem of the Middle Period was to establish whether this mysterious thing called "Humor'' really had objective existence or whether it existed only in the imagination. Those who believed it really existed were called Pro-Humorists; those who believed it did not were called skeptics or Anti-Humorists...
The Pro-Humorists were roughly of three sorts; the Rational Pro-Humorists, who claimed that the existence of Humor could be established by pure reason; the Faith-Humorists, who believed that reason could be somewhat helpful but that an act of faith was crucial; and finally there were the "Mystic-Humorists'' who claimed that neither reason nor faith were of the slightest help in apprehending Humor; the only reliable way it could be known was by direct perception...
The Mystic-Humorists kept repeating, "If only you could see humor directly, you would not need rational arguments nor any faith nor anything like that. You would then know that Humor is real.'' This phrase "see Humor directly'' was particularly apt to be criticized. The Mystic-Humorists actually said: "Yes, we can see humor in many situations. Life is permeated with humor, if you can only see it.''
The skeptical Anti-Humorists said, "So, you claim you can see humor! Tell me, what color is it?''
The Mystic-Humorists laughed and said, "Humor doesn't have any color!''
The skeptics continued: "Oh, so you can see it only in black and white! Well, then, what shape is it?''
"It doesn't have any form or shape.''
"Then I am confused! Is humor visible or invisible?''
"Of course it is invisible!''
"But I thought you just said that you can see it. Didn't you say that you could see the humor of certain situations?''
"Well, yes, I said that, but I didn't mean 'see' in the literal sense of 'see with your eyes.' Ocular vision really has nothing to do with it. I used 'see' in the sense of directly perceive, not see with the eyes. The perception, though as direct as vision, is really through a different sense altogether.''
"A different sense? Which sense is it---hearing? If so, what does humor sound like? Or is it smell or taste or touch or what? With which of the five senses do you perceive humor, or is it a combination of more than one of them?''
"No, it is not any one of these five senses, nor is it a combination of them. It is a different sense altogether---in a way, it is a nonphysical sense---we call this sense the 'sense of humor'.''
"Good God, you literally mean a nonphysical sense? In other words, you mean it is something occult like telepathy or clairvoyance? But scientific integrity requires us not to believe in anything occult; hence we cannot but believe that this Humor is something totally unreal, a mere figment of the imagination.''