--- - |2 A Bayesian mind is, at its core, a rational mind. Bayesianism is thus well‐suited to predict and explain mental processes that best exemplify our ability to be rational. However, evidence from belief acquisition and change appears to show that we do not acquire and update information in a Bayesian way. Instead, the principles of belief acquisition and updating seem grounded in maintaining a psychological immune system rather than in approximating a Bayesian processor. - Mind & Language, EarlyView.