Abstract
When theorists have studied humor, they often assumed that laughter was either a necessary or a sufficient condition of humor. It is neither. Although humorous events usually evoke laughter, they do not do so invariably. Humor may evoke smiles or smirks which fall short of laughter. Thus it is not a necessary condition. Nor is it a sufficient condition. People may laugh because they are uncomfortable (nervous laughter), they may laugh at someone (derisive laughter), they may laugh because they are insane or mentally imbalanced (hysterical laughter), or they may laugh because they are physiologically induced to do so (as when someone tickles them relentlessly). Perhaps these other forms of laughter are philosophically interesting, but they are not forms of humor and so are beyond the reach of this essay