Speech act

In the philosophy of language and linguistics, a speech act is an utterance considered as an instance of action in a social context rather than as the mere expression of a proposition. To say "I resign", "I apologise" or "You're fired" is, in suitable circumstances, to perform the very act of resigning, apologising or dismissing, not simply to describe it. Speech-act theory therefore treats speaking a language as a kind of rule-governed social behaviour in which people make claims, issue orders, ask questions, make promises and so on by means of utterances.

Following J. L. Austin and John R. Searle, many accounts distinguish at least three levels of act in ordinary utterances: the locutionary act of producing a meaningful expression, the illocutionary act performed in saying something (such as asserting, warning, requesting or promising), and the perlocutionary act consisting in its further effects on an audience, such as persuading, amusing or alarming them. Later work has added notions such as metalocutionary acts, which organise or comment on the discourse itself, and has analysed performative utterances and indirect speech acts, in which one kind of act is performed by way of another.

As a systematic theory, the contemporary notion of speech acts originates in Austin's 1955 Harvard lectures published as How to Do Things with Words, and in Searle's subsequent development of explicit rules and taxonomies for illocutionary acts. Historical research has identified important predecessors and parallels, including the later philosophy of Ludwig Wittgenstein, the accounts of "social acts" in the work of Thomas Reid and Adolf Reinach, and early-20th-century linguistic theories of Sprechhandlung ("speech action"), as well as earlier reflections in Hegel on speaking as a form of acting.

Speech-act theory now plays a central role in pragmatics, discourse analysis and communication studies, and has been taken up in a wide range of other fields. In language acquisition it is used to describe how children learn to perform basic communicative acts such as requesting, greeting and protesting; in computer science and information systems it underpins models of human–computer interaction, workflow and multi-agent system communication that treat messages as illocutionary moves creating and discharging commitments; in political science and international relations it informs theories of securitization and the construction of security; and in law, economic sociology and finance it has been applied to the performative role of legal norms and mathematical models in shaping social and economic practices.