Those who can make you believe absurdities, can make you commit atrocities.

This line is widely circulated under Voltaire’s name in modern political and secularist discourse, typically as a warning about religious or ideological credulity leading to violence. However, it does not appear in Voltaire’s authenticated writings in this wording. The closest well-attested Voltairean sentiment is in his 1763 “Traité sur la tolérance” (Treatise on Tolerance), written in the wake of the Jean Calas affair, where Voltaire attacks fanaticism and argues that superstition and unreason can license cruelty. The English aphorism seems to be a later paraphrase or condensation of Voltaire’s broader critique of fanaticism rather than a verbatim quotation.

The saying links epistemic manipulation to moral catastrophe: if an authority can train people to accept claims that defy reason (“absurdities”), it can also erode their moral inhibitions and recruit them for violence (“atrocities”). The underlying idea is that surrendering critical judgment—especially to dogma—makes individuals governable by fear, sacred duty, or group loyalty, so that cruelty can be reframed as virtue. Read in a Voltairean key, it is less an attack on faith per se than on fanaticism and the social mechanisms that turn superstition into persecution, urging skepticism, tolerance, and the discipline of reason as safeguards against collective brutality.