This paper focuses on aspects of the discourse of Donald Trump during his campaign for the U.S. Presidency. It argues that, although we can undoubtedly identify aspects of authoritarian populism in his campaign discourse, its appeal rested on more than its content. Indeed, although significant parts of the U.S. public sphere rejected many of his claims as lies, significant portions of the electorate found his words acceptable on some contrasting basis. By developing a comparison between Habermas's notion of 'validity claims' and Aristotle's distinctions between different kinds of rhetorical appeal, the paper suggests that a discourse of 'authenticity' rather than 'truth' provided a crucial cornerstone of Trump's appeal to his electoral base.