Interesting read, but I found some parts a bit confusing due to lack of examples. The article mentions the Incongruity Theory of Humour, which I've noticed about humour in the past, but there are other aspects of humour mentioned in the article that are worth considering as well.
When I found the book online, the examples page was missing. It's there in the book though. You could peek at it in a bookstore. The book itself is thoroughly entertaining, although there a couple small sad mistakes and then he really blows it in the last chapter (on the topic of consciousness).
Consider:
"A man died, and left his three sons a ranch. They decided to call the ranch Focus, because that's where the sun's rays meet."
"I was afraid for my life. I became a mathematician, for I'd heard that there was safety in numbers."
Those are both puns. The first is clever, man, a triple pun. It's not funny though. The second is less clever but actually a joke. What makes the second one a joke? I put it to you that it's loss of dignity.