In the summer of 1991 we were in Cayucos and I overheard the following conversation between a boy about 5 or 6 and his mother.

boy: What's under there?....under where? mother: I got that. Believe it or not I got that.

This was supposed to be a joke. The reason this was supposed to be funny was because the phrase "under where?" sounds like the word "underwear". The same series of phonetic sounds has two possible meanings. Most jokes are like this. The most famous joke, which isn't funny either, is "Why did the chicken cross the road? get to the other side". The listener first thinks the question is asking about the motive: why the chicken wanted to get to the other side. Then the listener learns that the question was concerned only with the actual crossing in and of itself. The listener first thinks the words mean one thing and then learn that they mean something else. There is a contradiction between what the listener initially thinks that the words mean and what they actually mean or are supposed to mean in the joke. Another famous joke is, "What's black and white and red all over?.... a newspaper." The listener initially thinks the word red is the color red since it's preceded by two colors, and then learns that it was the past tense of the verb "to read". The listener initially thinks the word means one thing and then finds out that it means something else. There is a contradiction between what the listener initially thinks the word means and what it actually means or is supposed to mean in the joke.

A famous vaudeville line is "Take my wife....please." The comedian is speaking about women and then acts like he's going to use his wife as an illustration. "All women talk too much...take my wife." The audience thinks he's going to mention some example of his wife talking to illustrate his point. Then he says "please" indicating that the real meaning of his words was that he wanted someone to take his wife off his hands. The audience initially thinks that he means one thing and then they find out he means something else. There is a contradiction between what they initially thought his words meant and what they actually mean or are supposed to mean in the joke.

At the most fundamental level, humor is the form of a contradiction. There is a famous episode of Sesame Street where a girl , about three or four, is reciting the alphabet with Kermit. This is what she says: "A....B....C....D....E....F....Cookie Monster." Then she bursts out laughing like this was the funniest thing in the world. The phrase "Cookie Monster" contrasts with what she had been saying .There was a contradiction between what she said and what she was supposed to say. The contradiction was the source of humor. This is evidence that it is the existence of a contradiction within the mind that is the fundamental trigger for laughter.

"What's black and white and red all over?" is more than simply a joke. It's a riddle, meaning you're supposed to try to figure it out. Let's say someone tells you the riddle and you try to figure it out. You can't figure it out and you say "what?" The person answers "a newspaper." You become conscious of both meanings of the word "red" and you laugh. Why does the process of becoming conscious of both meanings cause spontaneous laughter? Once you become conscious of both meanings you have more knowledge or a greater understanding than someone aware of one meaning. You are superior to someone who knows only one meaning. You then laugh at someone so stupid that they can only see one meaning, even though you yourself were such a person a fraction of a second earlier. To some extent you are in fact laughing at your former self, without laughing at or criticizing your current self. When you become aware of both meanings you then laugh at a hypothetical person, or your former self, that is only aware of one meaning. When you become aware of the second meaning, you become aware of a contradiction between what you thought the word meant and what it actually means. Therefore, whenever you laugh at a contradiction you are actually laughing at someone, if nothing else a hypothetical person or your former self. Therefore laughter resulting from a contradiction is a subdivision of laughter resulting from laughing at someone. At a deeper level laughter is an expression of a belief that you are superior to someone else. "You" and "someone else" have to be two different things, so you don't laugh if you are the butt of the joke. If you are too similar to the person being laughed at in some relevant sense, then there is not enough difference between these two things and you don't laugh. In order to laugh anyway, you have to put distance between yourself and the person laughed at.

The boy at the beach laughed at the underwear joke. However, probably the word "underwear" all by itself would cause him to laugh. In the joke there is a contradiction resulting from the double meaning of phonetic sounds: "under where" and "underwear". However, the word "underwear" all by itself involves a subtle contradiction. If you walk into a kindergarten class and say "underwear", kids will laugh but if you say "shirt" or "pants" they won't laugh. The reason is because since underwear isn't seen in public they think it isn't supposed to be mentioned in public. Therefore when you mention it there is a contradiction between what you're doing and what you're supposed to be doing. Laughter is derived from contradictions. If someone is violating a social taboo that person is therefore inferior to yourself and you can laugh at that person. This is the reason why dirty jokes are so prevalent in sit-coms and movies. However, if someone were simply saying sexually explicit things in public that would be violating a social taboo but would not alone elicit laughter. The reason is because if you laugh you are saying it's not a big deal and you are not offended. To not be offended by, or to condone, the violation of a taboo is itself a violation of a taboo. If you laugh, you would be violating a taboo and others would have a low opinion of you. Let's say someone says something with a double meaning in which one meaning is innocuous and the other is sexually explicit. You can pretend to see only the first meaning and then under that umbrella or pretext you can laugh at the second meaning. Wouldn't someone say why are you laughing at that first meaning? If someone were to do that, they would be saying that you are laughing at the second meaning, and thus that they see the second meaning and therefore have a dirty mind. If they were to criticize you for seeing the second meaning they would be admitting that they themselves see the second meaning. They can't accuse you without self-incrimination. Since you need not fear someone openly criticizing you, you're free to laugh.

There are people aside from myself who pointed out the connection between humor and contradiction. In 1968, Ertel did an experiment in which people were presented with pairs of nouns and adjectives They said that the incongruitous pairs were "funny" or "witty", the congruitous pairs were "normal", and the very incongruitous pairs were "absurd". A different experiment was done by Nerhardt in 1970. People were asked to lift a series of weights. The final weight in the series was much lighter or heavier than the others. Often, when they lifted the final weight, they laughed. It was the incongruity, or difference between what happened and what they expected would happen, that elicited laughter.

Berlyne wrote a series of papers (1960, 1967, 1971) analyzing the purpose of humor. He defines "arousal potential" as "stimulus properties that tend to drive arousal upward, including intensity, inherent or conditioned biological significance, and collative properties." He defines "hedonic value" as "pleasure, manifested through verbal reports or expressive behavior, and reward value, manifested through reinforcement of learned responses." An "arousal boost" is a mechanism where if arousal rises, it causes hedonic value to rise. An "arousal jag" is a situation where arousal falls after having risen to high, and this causes hedonic value to increase. In humor, usually there is a moderate rise in arousal that causes us to gain hedonic value, after which it rises to high and then drops which causes us to gain additional hedonic value. Humor is thus often described as an "arousal boost-jag". By graphing hedonic value versus arousal potential, we get the Wundt curve, introduced by Wundt in 1874. He used it to link pleasure with stimulus intensity, although we give it broader interpretation than he did.

Zigler et al. (1967) wrote about the "degree of cognitive congruence existing between the cognitive demand features of the humor stimulus and the cognitive resources of the individual." Easy jokes don't make a person think hard, so the arousal never rises into the uncomfortable range. Therefore, there is no pleasure deriving from an ancestral jag. More difficult jokes make a person think and the arousal rises into the uncomfortable range. Therefore, there is an arousal jag and the pleasure that derives from it. Things that could raise arousal potential include stimulus intensity and collative properties. This could be trying to figure out a difficult joke. This could also come from having two contradictory ideas in the mind simultaneously. The mind flips back and forth between them and the confusion that arises, the difficulty in figuring it out, could increase arousal potential.