Do We Live in a 'Post-Truth' Era?

Have we entered a 'post-truth' era? This article is an attempt to answer this question by (a) offering an explication of the notion of 'post-truth' from recent discussions, (b) deriving a testable implication from that explication, to the effect that we should expect to see decreasing information effects - that is, differences between actual preferences and estimated, fully informed preferences - on central political issues over time and then (c) putting the relevant narrative to the test by way of counterfactual modelling, using election year data for the period of 2004-2016 from the American National Election Studies' Times Series Study. The implication in question turns out to be consistent with the data: at least in a US context, we do see evidence of a decrease in information effects on key, political issues - immigration, same-sex adoption and gun laws, in particular - in the period 2004-2016. This offers some novel, empirical evidence for the 'post-truth' narrative.