John L. Austin: How To Do Things With Words, 1955

Utterances can be found […] such that:

    A. they do not ‘describe’ or ‘report’ or constate anything at all, are not ‘true or false’; and
    B. the uttering of the sentence is, or is a part of, the doing of an action, which again would not normally be described as, or as ‘just,’ saying something.

This is far from being as paradoxical as it may sound or as I have meanly been trying to make it sound: indeed, the examples now to be given will be disappointing.

Examples:

    (E. a.) ‘I do (sc. take this woman to be my lawful wedded wife)’—as uttered in the course of the marriage ceremony.
    (E. b.) ‘I name this ship the Queen Elizabeth’—as uttered when smashing the bottle against the stem.
    (E. c.) ‘I give and bequeath my watch to my brother’—as occurring in a will.
    (E. d.) ‘I bet you sixpence it will rain tomorrow.’

In these examples it seems clear that to utter the sentence (in, of course, the appropriate circumstances) is not to describe my doing of what I should be said in so uttering to be doing or to state that I am doing it: it is to do it. None of the utterances cited is either true or false: I assert this as obvious and do not argue it. It needs argument no more than that ‘damn’ is not true or false: it may be that the utterance ‘serves to inform you’-but that is quite different. To name the ship is to say (in the appropriate circumstances) the words ‘I name, &c.’. When I say, before the registrar or altar, &c., ‘I do’, I am not reporting on a marriage: I am indulging in it.

What are we to call a sentence or an utterance of this type? I propose to call it a performative sentence or a performative utterance, or, for short, a ‘performative.’

Austin, John L. How To Do Things With Words, The William James Lectures delivered at Harvard University in 1955. Edited by James O. Urmson. London: Oxford University Press, 1962.
via