John L. Austin was a British philosopher of language and leading proponent of ordinary language philosophy, perhaps best known for developing the theory of speech acts. Austin pointed out that we use language to do things as well as to assert things, and that the utterance of a statement like "I promise to do so-and-so" is best understood as doing something - making a promise - rather than making an assertion about anything. Hence the name of one of his best-known works How to Do Things with Words. Austin, in providing his theory of speech acts, makes a significant challenge to the philosophy of language, far beyond merely elucidating a class of morphological sentence forms that function to do what they name. Austin's work ultimately suggests that all speech and all utterance is the doing of something with words and signs, challenging a metaphysics of language that would posit denotative, propositional assertion as the essence of language and meaning.