We laugh at things that are laughable, but also laugh exultantly at a success, or bitterly at a failure, or at the unexpected or even the typical. We may even laugh but not at anything—with pure joy, or nervousness, or embarrassment, or merely because we have been physically tickled. The variety of causes or objects of laughter, and the absence of any obvious explanation of its function, have not deterred theorists. Hobbes thought that the passion of laughter is a ‘sudden glory arising from some sudden conception of some eminency in ourselves’ (Human Nature, ix. 12). Hutcheson wrote against the egoism of this account (‘Reflections on Laughter’, Dublin Journal, 1725), locating humour instead in a perception of incongruity, although he offered no real evidence that incongruity is either a necessary or a sufficient condition of something appearing comical. Bain (The Emotions and the Will, 1859) identifies the ludicrous with ‘the degradation of some person or interest possessing dignity, in circumstances that excite no other strong emotion’. Kant (Critique of Judgement, 1790) emphasizes the element of the unexpected, identifying laughter as ‘an affection arising from a strained expectation being suddenly reduced to nothing’. His view is expanded by Schopenhauer, who again finds incongruity at the basis of laughter. But as the Hobbes-Bain approach reminds us, it is not only the insult to reason that is funny but often the insult to other people. In his book Le Rire: essai sur la signification du comique (1900), perhaps anticipating the comedians Jacques Tati or Charlie Chaplin, Bergson locates comedy as a defence against automatic, disjointed qualities that trespass against the essential spontaneity of life.

The capacity to take something as an occasion for humour evidently has a social function: it connects with play and with the rehearsal and defusing of potential conflict, but also can give rise to the more aggressive exclusion of persons and groups from consideration, by refusal to take them seriously, or by mockery and ridicule.