Contrarian Conspiracy Theories and Higher-Order Evidence

Is it always epistemically irrational to believe a conspiracy theory? Not on principle. According to the standard definition in the philosophical literature, conspiracy theories are too wide and heterogenous a class for us to proffer any universal rules re their rationality. This does not mean, however, that we cannot offer any useful generalisations. This paper argues that one useful generalisation concerns the contrariness of some conspiracy theories. Whilst we cannot say that it is always irrational to believe a conspiracy theory, ceteris paribus, it is irrational to believe a contrarian conspiracy theory. A conspiracy theory is contrarian when recognised credible epistemic authorities reject that theory. When a conspiracy theory is contrarian the conspiracy theorist will, by default, possess negative higher-order evidence for the theory in question – that is, evidence that they may have made a mistake in the deliberations that led them to believe the relevant theory. In general, on acquiring negative higher-order evidence one acquires an undercutting defeater for whatever justification one otherwise has for the relevant beliefs. Therefore, absent a defeater-defeater, one will no longer be justified in holding the relevant beliefs. Applied to conspiracy theories, then, the consequences are simple enough. If a theory is contrarian, one will, by default, possess an undercutting defeater for whatever evidence on the basis of which one may have come to believe that theory. Absent a defeater-defeater for the relevant higher-order evidence, then, it is not rational for one to believe a conspiracy theory when that theory is contrarian.