--- - |2 Abstract I offer two potential diagnoses of the behavioral norms governing post‐truth politics by comparing the view of language, communication, and truth‐telling put forward by David Lewis (extended by game theorists), and John Searle. My first goal is to specify the different ways in which Lewis, and game theorists more generally, in contrast to Searle (in the company of Paul Grice and Jürgen Habermas), go about explaining the normativity of truthfulness within a linguistic community. The main difference is that for Lewis and game theorists, “truthful” signaling follows from an alignment of interests, and deception follows from mixed motives leading to the calculation that sending false information is better for oneself. Following in the Enlightenment tradition, Searle argues that practical reasoning, which involves mastery of at least one language, requires that actors intend to communicate. This intention includes constraining the content of statements to uphold veracity conditions. After distinguishing between these two accounts, I will articulate the implications for explaining, and even informing actions, constitutive of post‐truth politics. I argue that the strategic view of communication is sufficient neither to model everyday conversation nor to reflect a public sphere useful for democratic government. Both the pedagogy of strategic communication as cheap talk, and its concordance with new digital information technologies, challenge norms of truthfulness that underlie modern institutions essential to an effective public sphere. - Journal for the Theory of Social Behaviour, Volume 48, Issue 3, Page 306-329, September 2018.