There is now an entry on “Philosophy of Humor” in the Stanford Encyclopedia of Philosophy. It’s serious business, but here’s a passage about Kant’s philosophy of the funny:
Immanuel Kant, a contemporary of Beattie’s, did not used the term incongruous but had an explanation of laughter at jokes and wit that involves incongruity.
In everything that is to excite a lively convulsive laugh there must be something absurd (in which the understanding, therefore, can find no satisfaction). Laughter is an affection arising from the sudden transformation of a strained expectation into nothing. This transformation, which is certainly not enjoyable to the understanding, yet indirectly gives it very active enjoyment for a moment. Therefore its cause must consist in the influence of the representation upon the body, and the reflex effect of this upon the mind.
Kant illustrates with this story:
An Indian at the table of an Englishman in Surat, when he saw a bottle of ale opened and all the beer turned into froth and overflowing, testified his great astonishment with many exclamations. When the Englishman asked him, “What is there in this to astonish you so much?” he answered, “I am not at all astonished that it should flow out, but I do wonder how you ever got it in.”
We laugh at this story, Kant says, “not because we deem ourselves cleverer than this ignorant man, or because of anything in it that we note as satisfactory to the understanding, but because our expectation was strained (for a time) and then was suddenly dissipated into nothing.”
“We must note well,” Kant insists, that it [our expectation] does not transform itself into the positive opposite of an expected object… but it must be transformed into nothing.” He illustrates with two more jokes:
The heir of a rich relative wished to arrange for an imposing funeral, but he lamented that he could not properly succeed; ‘for’ (said he) ‘the more money I give my mourners to look sad, the more cheerful they look!’
[A] merchant returning from India to Europe with all his wealth in merchandise … was forced to throw it overboard in a heavy storm and … grieved thereat so much that his wig turned gray the same night.”