Abstract: Humans depend massively on communication with others, but this leaves them open to the risk of being accidentally or intentionally misinformed. We claim that humans have a suite of cognitive mechanisms for epistemic vigilance to ensure that communication remains advantageous despite this risk. Here we outline this claim and consider some of the ways in which epistemic vigilance works in mental and social life by surveying issues, research and theories in different domains of philosophy, linguistics, cognitive psychology and the social sciences.