Analyses of so-called ‘post-truth’ discourse in populist politics have so far largely focussed on sorting it into cases of lying, bullshitting, bubble-like epistemic constraints, or alternative epistemic norms flouting objective truth. We review these proposals and point out problems with each. Some scholars, however, have recently drawn attention to how apparent assertions of facts in these contexts seem to be functionally entangled with expressing or affirming social identities. To get a clearer picture of what such an explanation might amount to, we differentiate four different ways in which social identities might be connected to apparently assertive discourse: signalling, expressive affirmation, dissonance reduction, and identity grounding. Distinguishing and deciding among these will matter not only for providing an accurate analysis of post-truth discourse, but also for determining the exact grounds on which it merits criticism and for what might be done about it.