In J.L. Austin's formulation of Speech act theory, a performative utterance

Performative utterance

The notion of performative utterances was introduced by language philosopher J. L. Austin. According to his original conception, it is a sentence which does something in the world rather than describing something about it...

 is neither true nor false, but can instead be deemed "felicitous" or "infelicitous" according to a set of conditions whose interpretation differs depending on whether the utterance

Utterance

In spoken language analysis an utterance is a complete unit of speech. It is generally but not always bounded by silence.It can be represented and delineated in written language in many ways. Note that in such areas of research utterances do not exist in written language, only their representations...

 in question is a declaration ("I sentence you to death"), a request ("I ask that you stop doing that") or a warning ("I warn you not to jump off the roof").

Felicity conditions for declarations

• Conventionality of procedure: the procedure (e.g. an oath
  Oath
  An oath is either a statement of fact or a promise calling upon something or someone that the oath maker considers sacred, usually God, as a witness to the binding nature of the promise or the truth of the statement of fact. To swear is to take an oath, to make a solemn vow...
  
  ) follows its conventional form
• Appropriate participants and circumstances: the participants are able to perform a felicitous speech act under the circumstances (e.g. a judge can sentence a criminal in court, but not on the street)
• Complete execution: the speaker completes the speech act without errors or interruptions
• Sincerity condition: the utterance counts as the speaker's will

Felicity conditions for requests

• Propositional content condition: the requested act is a future act of the hearer
• Preparatory precondition: 1) the speaker believes the hearer can perform the requested act; 2) it is not obvious that the hearer would perform the requested act without being asked
• Sincerity condition: the speaker genuinely wants the hearer to perform the requested act
• Essential condition: the utterance counts as an attempt by the speaker to have the hearer do an act

Felicity conditions for warnings

• Propositional content condition: it is a future event
• Preparatory precondition: 1) the speaker believes the event will occur and be detrimental to the hearer; 2) the speaker believes that it is not obvious to the hearer that the event will occur
• Sincerity condition: the speaker genuinely believes that the event will be detrimental to the hearer
• Essential condition: the utterance counts as an attempt by the speaker to have the hearer recognize that a future event will be detrimental