This chapter focuses on two main filtering mechanisms: trust and reputation. It aims to distinguish different mechanisms, both social and cognitive, that is at the basis of our trust in others and illustrates how they can be adjusted in communicative settings to maximize our acquisition of knowledge from others. Social epistemology is the study of the influence of social mechanisms and social institutions in the production, diffusion and legitimization of knowledge. Among the many social mechanisms that filter our access to knowledge and contribute to the very construction and maintenance of our knowledge institutions. Knowledge is a complex social practice that involves cognitive abilities, communicative skills and social roles. Trust as an epistemic relation always implies a communicative context in which the heuristics are employed by following a number of pragmatic rules. The psychological disposition to trust the other can be determined by emotional, non-reasoned reactions.