Laughter provoked by literature is a wonderful opportunity for analysis because it is likely to expose important social or aesthetic rules that often operate without our being aware of them. No single explanation of humor satisfies careful study because such a wide variety of occasions can stimulate the response in attentive readers. The following is a quick summary of major opinions, historically organized and without a drop of wit intended.
Aristotle's Poetics explained comedy as a genre rooted in the discovery of deformity, physical or psychological. Romans like Cicero and Quintilian tended to emphasize the latter, especially as psychological deformity resulted in a loss of morality or sense of beauty (Chapman and Foot 1).
Ben Jonson is cited as the first major author to treat laughter as a "social corrective in its use as criticism of the follies of mankind" (Chapman and Foot 1; see, for instance, the prologue to Volpone, or, The Fox). Though Swift and others considered the capacity to laugh as one of the defining traits of humanity, more recent researchers from Darwin to the present have agreed that all apes laugh (Chapman and Foot 2). Other authors treat the open expression of humor as degrading to the laugher, like Lord Chesterfield ("there is nothing so illiberal and so ill-bred as audible laughter"), John Ray ("the hiccup of a fool"), or Wyndham Lewis ("the mind sneezing") (all qtd. Chapman and Foot 3).
Thomas Hobbes proposed that the laugher's reaction was a response to a perceived superiority to the object of the laughter, a sense he called "Sudden Glory" and derided as unworthy of "great minds" whose duty is "to help and free others from scorn" (from Leviathan, qtd. in La Fave, Haddad and Maesen 61).
James Beattie (1775) suggested that humans laugh when witnessing painful experiences of others or even their own pain as a way to survive otherwise intolerable misfortunes of life.
Sigmund Freud's Wit and its Relation to the Unconscious (published in German as Witz, 1905) explains laughter and jokes as the operation of transgressive unconscious instincts that channel psychic energy toward the safe release of laughter when the laugher is confronted with the threat of social or psychological disorder (Kincaid "Chapter 1, Introduction, Part 2"). Freud accepts humor's critics' association of open laughter with infantile or socially reprehensible behavior, but observes that society ordinarily permits laughter as a sanctioned violation of discourse norms. One might easily prove Freud's point by listing the kinds of occasions in which open laughter is forbidden (e.g., symphony concerts, funerals [ordinarily], weddings [ordinarily], bank robberies, national disasters, and final exams), though comedy often visits precisely these settings to allow audiences to witness the comic spectacle of repressed laughter.
Henri Bergson draws attention to the species of laughter deriving from perceived "conflict of the rigid and mechanical with the flexible and organic," producing laughter "every time a person gives us the impression of being a thing" or a thing, a person (Kincaid, and Bergson qtd. in Kincaid).
This web page draws upon the work of James R. Kincaid, Dickens and the Rhetoric of Laughter (Oxford: Clarendon P, 1971; available online at the Victorian Web: http://www.victorianweb.org/authors/dickens/kincaid2/contents.html), and essays in Antony J. Chapman and Hugh C. Foot, Eds., Humour and Laughter: Theory, Research and Applications (N.Y.: John Wiley, 1976), including the editors' introductory essay, Thomas R. Schultz's "A Cognitive-Developmental Analysis of Humour," Mary K. Rothbart, "Incongruity, Problem-Solving and Laughter," and Lawrence La Fave, Jay Haddad, and William A. Maesen, "Superiority, Enhanced Self-Esteem, and Perceived Incongruity Humour Theory" (1-7,11-36, 37-54, 63-91). Of these essays, perhaps the funniest is Rothbart's, which includes a full-page flow-chart (Figure 2.1) of the cognitive steps leading from minimal to high "Evoked Arousal Level" of humorous reactions to stimuli in varying contexts, each of which ends in the process labeled "Tension Release" which produces physiognomic reactions from "Smile" to "Laugh or big smile" to the big enchilada, "Laugh" (39).
Also see, James Beattie, Essays: on poetry and music, as they affect the mind; on laughter, and ludicrous composition; on the usefulness of classical learning. 3rd Edition (corrected) London: E. and C. Dilly, W. Creech, 1779. Special Collections ML60 .B4 1779