Heterodox ideas face an uphill battle. This is not least the case for heterodox conspiracy theories. As an empirical observation, this is hardly controversial. What is controversial is whether and to what extent this should be the case. Some authors have gone so far as to argue that heterodox conspiracy theories should be generally dismissed, and that it is precisely their heterodox status that justifies such dismissal. Most particularists are likely to object strongly to such an assessment, arguing that conspiracy theories–whether heterodox or orthodox–should not be dismissed before careful examination of the relevant evidence. But even particularists will probably concede that proponents of heterodox conspiracy theories have to bear a special epistemic burden. The main aim of this paper is to take a closer look at this particular epistemic burden. Drawing on the literature about peer disagreement, genealogical debunking arguments, and related philosophical debates, I focus in particular on the question of whether and under what conditions it can be rational to defend heterodox conspiracy theories, and argue that what I will call theories of error play a crucial role in this context.