Belief in conspiracy theories is often taken to be a paradigm of epistemic irrationality. Yet, as I argue in the first half of this paper, standard criticisms of conspiracy theorising fail to demonstrate that the practice is invariably irrational. Perhaps for this reason, many scholars have taken a relatively charitable attitude toward conspiracy theorists and conspiracy theorising in recent years. Still, it would be a mistake to conclude from the defence of conspiracy theorising offered here that belief in conspiracy theories (...) is on an epistemic par with belief in other theories. I argue that a range of epistemic errors are pervasive among conspiracy theorists. First, the refusal of conspiracy theorists to accept the official account of some target event often seems to be due to the exercise of a probabilistic, and fallacious, extension ofmodus tollens. Additionally, conspiracy theorists tend to be inconsistent in their intellectual attention insofar as the effort they expend on uncovering the truth excludes attention to their own capacities for biased or otherwise erroneous reasoning. Finally, the scepticism with which conspiracy theorists tend to view common sources of information leaves little room for conspiracy theorists to attain positive warrant for their preferred explanations of target events. (shrink)