According to some prominent theorists, the conditions of deliberative democracy call for reasoned decisions from mutually justifiable premises. The deliberative ideal places demands on the epistemic quality of the deliberating process and on the epistemic habits and beliefs of the relevant agents. In this essay, I discuss this ideal in light of empirical literature. I examine some empirical literature on human reasoning that paints a bleak picture of human rationality: we fall victim to heuristics and biases, persevere in our beliefs in the face of contrary evidence, and justify our current moral judgments by post hoc-reasoning. In addition, the deliberating groups have specific problems. The groups may, for example, amplify errors or fall victim to information cascades. I argue that, given that we are interested in securing that deliberative process is epistemically valuable, the literature gives further support to the idea that education must foster not only skills but also dispositions for critical thinking. I conclude with a brief defense of epistemic internalism against the argumentation by M. Solomon (2006).