I argue that trust is epistemically important because it is the foundation of social practices that confer significant epistemic benefits on scientific communities. I begin by showing the limitations of the dominant rational choice account of trust, which maintains that trust is rational when the truster has good reason to believe that it is in the trusted's self-interest to act trustworthily. These limitations motivate my alternative account of trust, which recognizes non-self-interested motivations for acting trustworthily, such as having a sense of duty. The first part of the account captures the cognitive aspect of trust. When we trust, we take a particular cognitive attitude towards the claim that the trusted will do what we expect her...