Speech act theory is generally traced back to British philosopher JL Austin who presents the idea in the very readable paper “How to do Things with Words.” Put simply, a speech act is when language is used to change the state of affairs in the world. Austin’s classic example is the uttering of “I hereby pronounce you husband and wife” during a wedding ceremony. With these words, the legal status of the happy couple is changed. In fact the phrase “I hereby…” is a common way of expressing a speech act: “I hereby declare war,” “I hereby name this ship…,” “I hereby announce that the winner is…” For more on this, see the summary of “Performative Utterances.”