Recently, both evolutionary anthropologists and some philosophers have argued that cooperative social settings unique to humans play an important role in the development of both our cognitive capacities and what Michael Tomasello terms the “construction” of “normative rationality” or “a normative point of view as a self-regulating mechanism.” In this article, I use evolutionary game theory to evaluate the plausibility of the claim that cooperation fosters epistemic rationality. Employing an extension of signal-receiver games that I term “telephone games,” I show (...) that cooperative contexts work as advertised: under plausible conditions, these scenarios favor epistemically rational agents over irrational ones designed to do just as well as them in non-interactive contexts. I then show that the basic results are strengthened by introducing complications that make the game more realistic. (shrink)