Critical Discourse Analysis has recently begun to consider the implications of research in Evolutionary Psychology for political communication. At least three positions have been taken: i) that this research requires Critical Discourse Analysis to re-examine and defend some of its foundational assumptions (Chilton, 2005); ii) that this research provides a useful explanatory framework for Critical Discourse Analysis in which questions can be addressed as to why speakers might pursue particular discursive strategies and why they might be so persuasive (Hart, 2010); and iii) that findings bare little or no relevance for Critical Discourse Analysis (Wodak, 2006). In this article, I take up the first two of these positions and in doing so, of course, implicitly disagree with the third. I consider the positions in i) and ii), then, specifically in relation to Sperber’s (2000, 2001) notion of a ‘logico-rhetorical’ module. Taking the argument that Chilton makes concerning this module one stage further, I suggest that the logico-rhetorical module evolved as much for persuasion as it did for vigilance. I further suggest that the semantic category of evidentiality operationalized in media discourse serves to satisfy the conditions of acceptance laid down by the logico-rhetorical module. I show how this semantic category therefore performs a legitimizing function in media discourse on immigration.