"The Will to Believe" is the title of William James's classic lecture (published in 1897) defending the adoption of beliefs as hypotheses and self-fulfilling prophecies even without prior evidence of their truth. James' idea that people have a right to do so is an uncontroversial part of his doctrine since many philosophers would agree with him that we have a right to hypothesize and adopt self-fulfilling beliefs without evidence. However, James extends this idea to argue that, using this doctrine, adopting beliefs like God, freewill, possibility, and morality would cause evidence to come, thus verifying beliefs that could not have been verified otherwise. James' rationale for this more controversial idea is in combining it with his pragmatic theory of truth, the idea that a belief is verified if it causes better interaction with the world. For example, while no evidence can justify the initial adoption of a belief in God, the adoption of such a belief as a hypothesis without evidence would cause one to succeed better in the world, thus verifying the belief. This does not entail that it will be verified for everyone, but rather, for many, that it would cause their lives to be better, thus making it true for them (see James' pluralism regarding truth).

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