Performative statements are much discussed in the philosophy of language, e.g., by the linguistic philosopher, J. L. Austin, where they are distinguished from descriptive statements. Whereas the latter merely describe a current state of affairs from an external standpoint, performative statements enact a new state of affairs merely by being spoken, as when a minister pronounces a couple married during a wedding ceremony. Performative statements are words and deeds at the same time. They are special kinds of statements, requiring certain unique circumstances and relationships so that they can function validly. Leston Havens has made the connection between the ability to make performative statements and the setting of psychotherapy. He has asserted that performative statements are an important part of the psychotherapeutic repertoire and may be an important force in bringing about psychotherapeutic change. In this paper, I try to locate the mechanism by which performative statements may achieve this effect, suggesting that this occurs by means of influencing the patient's will directly. Performative statements work on the will, much as descriptive statements influence the intellect. Philosophical ideas about the will, like Aristotle's notion of weakness of will, may explain some of the phenomena of psychotherapy, including resistance.