Inside Jokes: Using Humor to Reverse-Engineer the Mind by Matthew M. Hurley, Daniel C. Dennett, Reginald B. Adams Jr. contains the best theory I’m familiar with that explains humor.

As longtime readers of this blog know, I’ve been interested in what makes things funny for a long time, and wrote an early post about it.

I cannot hope to do justice to the theory of the book, so I won’t really try. I hope all who are interested will read the book itself. It’s very rewarding. While it does spend a bit of time on background issues, it’s very readable and is peppered with lots of good jokes and witticisms used for illustration.

For those who won’t read it, or are curious about the theory, I’ll try to give a small taste.

Humor, like beauty, is in the mind of the beholder. There isn’t a formula guaranteed to generate mirth, but mirth is something that happens within the receiver’s brain, and different people will have different reactions to the same stimulus (of course).

The basic idea is that various reward systems have evolved to help human genes propagate. Just as we evolved a “Sweet Tooth” reward system that leads us to find pleasure in tastes that are correlated with high-energy content, we also evolved a “Joy of Debugging” reward system that leads us to find pleasure (mirth) in detecting and refuting certain sorts of errors that make their way into our thinking. Basically, the sorts of error-detections that generate mirth tend to be that of refuting covertly entered, active, committed, beliefs.

In the book, the details are explained and refined. There is much discussion of mental-spaces, JITSA (Just-In-Time Spreading Activation), etc., as well as many variations (first-person, third-person, recursive levels of modeling various intentional agents) and lots of analysis of how various types of mirth-inducing stimuli (including tickling!) conform to the theory, and much discussion of related issues.

Again, if you’re interested in what humor is all about, I’m sure you’ll find the book well worth your time.