How can I give you a reason to believe what I tell you? I can influence the evidence available to you. Or I can simply invite your trust. These two ways of giving reasons work very differently. When a speaker tells her hearer that p, I argue, she intends that he gain access to a prima facie reason to believe that p that derives not from evidence but from his mere understanding of her act. Unlike mere assertions, acts of telling (...) give reasons directly. They give reasons by inviting the hearer’s trust. This yields a novel form of anti-reductionism in the epistemology of testimony. The status of testimony as a sui generis source of epistemic warrant is entailed by the nature of the act of telling. We can discover the nature of this illocution, and its epistemic role, by examining how it functions in the real world of human relations. (shrink)