Performative utterances (or performatives) are defined in the speech acts theory (part of the philosophy of language) as sentences which are not only passively describing a given reality, but they are changing the (social) reality they are describing.
History of the term 
In his 1955 William James lecture series, which were later published under the title How to Do Things with Words, Austin argued against a positivist philosophical claim that the utterances always "describe" or "constate" something and are thus always true or false. After mentioning several examples of sentences which are not so used, and not truth-evaluable (among them non-sensical sentences, interrogatives, directives and "ethical" propositions), he introduces "performative" sentences as another instance.
Austin's definition 
In order to define performatives, Austin refers to those sentences which conform to the old prejudice in that they are used to describe or constate something, and which thus are true or false; and he calls such sentences "constatives". In contrast to them, Austin defines "performatives" as follows:
- (1) Performative utterances are not true or false, that is, not truth-evaluable; instead when something is wrong with them then they are "happy" or "unhappy".
- (2) The uttering of a performative is, or is part of, the doing of a certain kind of action (Austin later deals with them under the name illocutionary acts), the performance of which, again, would not normally be described as just "saying" or "describing" something (cf. Austin 1962, 5).
For example, when Peter says "I promise to do the dishes" in an appropriate context then he thereby does not just say something, and in particular he does not just describe what he is doing; rather, in making the utterance he performs the promise; since promising is an illocutionary act, the utterance is thus a performative utterance. If Peter utters the sentence without the intention to keep the promise, or if eventually he does not keep it, then although something is not in order with the utterance, the problem is not that the sentence is false: it is rather "unhappy", or "infelicitous", as Austin also says in his discussion of so-called felicity conditions. In the absence of any such flaw, on the other hand, the utterance is to be assessed as "happy" or "felicitous", rather than as "true". Austin dropped this distinction in favour of a distinction between explicit performatives (like I promise it will never happen again) and primary or implicit performatives (like It will never happen again, functioning as a promise).
The initial examples of performative sentences Austin gives are these:
- 'I do (sc. take this woman to be my lawful wedded wife)' -- as uttered in the course of the marriage ceremony.
- 'I name this ship the "Queen Elizabeth"'
- 'I give and bequeath my watch to my brother' -- as occurring in a will
- 'I bet you sixpence it will rain tomorrow' (Austin 1962, 5)
As Austin later notices himself, these examples belong (more or less strikingly) to what Austin calls, explicit performatives; to utter an "explicit" performative sentence is to make explicit what act one is performing. However, there are also "implicit", "primitive", or "inexplicit" performatives. When, for instance, one uses the word "Go!" in order to command someone to leave the room then this utterance is part of the performance of a command; and the sentence, according to Austin, is neither true nor false; hence the sentence is a performative; -- still, it is not an explicit performative, for it does not make explicit that the act the speaker is performing is a command.
As Austin observes, the acts purported to be performed by performative utterances may be socially contested. For instance, "I divorce you", said three times by a man to his wife, may be accepted to constitute a divorce by some, but not by others.
Examples (mainly of explicit performative utterances) 
- "I now pronounce you man and wife." - used in the course of a marriage ceremony
- "Go" - used in ordering someone to go
- "Yes" - answering the question "Do you promise to do the dishes?"
- "You are under arrest." - used in setting someone under arrest
- "I christen you"
- "I accept your apology"
- "I sentence you to death"
- "I divorce you, I divorce you, I divorce you" (Islamic: see: Talaq-i-Bid'ah or triple Talaq)
- "I do" – wedding
- "I swear to do that", "I promise to be there"
- "I apologize"
- "I dedicate this..." (...book to my wife; ...next song to the striking Stella Doro workers, etc.)
- "This meeting is now adjourned", "The court is now in session"
- "This church is hereby de-sanctified"
- "War is declared"
- "I quit" – employment
- "I resign" – employment, or chess
True/false value and John Searle 
John R. Searle argued in his 1989 article How Performatives Work that performatives are true/false just like constatives. Searle further claimed that performatives are what he calls declarations; this is a technical notion of Searle's account: according to his conception, an utterance is a declaration, if "the successful performance of the speech act is sufficient to bring about the fit between words and world, to make the propositional content true." Searle believes that this double direction of fit contrasts the simple word-to-world fit of assertives.
The receiving side 
Bach and Harnish claimed that performatives are successful only if recipients infer the intention behind the literal meaning, therefore the success of the performative act is determined by the receiving side.
Performativeness as non-dichotomous variable 
Eve Sedgwick argued that there are performative aspects to nearly all words, sentences, and phrases. Additionally, according to Sedgwick, performative utterances can be 'transformative' performatives, which create an instant change of personal or environmental status, or 'promisory' performatives, which describe the world as it might be in the future. These categories are not exclusive, so an utterance may well have both qualities. As Sedgwick observes, performative utterances can be revoked, either by the person who uttered them ("I take back my promise"), or by some other party not immediately involved, like the state (for example, gay marriage vows).
Words on a list can be either descriptive or performative. 'Butter' on a shopping list implies that "I will buy butter" (a promise to yourself). But 'Butter' printed on your till receipt means "you have purchased butter" (simply a description).
Performative writing 
The above ideas have influenced performative writing; they are used as a justification for an attempt to create a new form of critical writing about performance (often about performance art). Such a writing form is claimed to be, in itself, a form of performance. It is said to more accurately reflect the fleeting and ephemeral nature of a performance, and the various tricks of memory and referentiality that happen in the mind of the viewer during and after the performance.
- Austin, J.L. How to Do Things with Words Oxford: Clarendon Press, 1962. ISBN 0-19-824553-X