A preparatory condition is a state of affairs that
- must be presupposed by the speaker in employing a particular illocutionary force, and
is a necessary condition for the nondefective employment of that force
- The force of making a promise, in which the speaker presupposes his or her own capability of performing the promised action
The distinction between promising and threatening
The act of promising presupposes the addressee’s concern that the promised action be taken, whereas the act of threatening presupposes some harm in the action.