The truth value of keeping promises

by hexacoto

What does it mean when someone promises you something?

“I promise to give you $10.”

In our everyday usage of this sentence, the person who utters this statement obliges himself to give the listener $10, is it not? However, if I utter this sentence and didn’t give you $10, is that sentence considered to be a false statement?

Most people would say “yes,” but in the study of semantics it is not that clear-cut.

What is the meaning of the sentence “I promise,”? To pare down its meaning, that sentence means “I am making a statement about agreeing to do something.” The most important and vital part about promises is that it has to be uttered. A promise is useless if the promiser doesn’t say it to the promisee. While a person can promise himself about something regarding other people (“I promise to protect her from harm.”), the promise is not valid to other people unless they hear it from the promiser (“Why’re you trying to stop me from crossing the road!?” “Oh I made a promise to protect you from harm.” “Get away from me you creep!”).

In semantics, this is known as a performative speech act, whereby a statement is true by virtue of being uttered.

Therefore, when I say, “I promise to give you $10,” did I make a promise to give you $10? Yes I did. Am I going to give you $10? I can’t afford to, I’m poor. But there is no way to look at the sentence I uttered earlier (“I promise to give you $10”) and say that that sentence is not true, because I did promise. I just did not keep my promise.

Tense matters when it comes to performative speech acts. When you change that example sentence to the past tense, “I promised to give you $!0,” that sentence can be false, because if you made no such promise prior, it is false. The future tense is slightly trickier — “I will promise to give you $10.” Is that itself a promise to exact a promise in the future, since “will” seems to have similar ‘promising’ functions, although slightly weaker than “promise” itself? Or is it a lot simpler, where its truth value is determined by whether the described action is carried out in the future?

Other fun examples to think about include:

  • “I now pronounce you man and wife.” – Are the couple not man and wife prior to the speech act, as they go through the wedding?
  • “You are under arrest.” – Was the person prior to the sentence not under arrest, even though he might be cuffed?
  • “I sentence you to death.” – Was the convict not sentenced to death prior to the utterance of the verdict, even though the jury had already decided?