Irrationally held truths may be more harmful than reasoned errors.

Huxley’s aphorism contrasts two kinds of intellectual failure: believing something true for bad reasons, and believing something false for good reasons. A “reasoned error” remains corrigible because it is tethered to evidence and argument; when new facts arrive, the error can be revised. An “irrationally held truth,” by contrast, is insulated from criticism—its holder treats it as a possession or identity rather than a conclusion—so it can license dogmatism, persecution, or policy made without accountability. The line thus defends scientific habits of mind: fallibilism, openness to refutation, and the moral value of giving reasons, even at the cost of being wrong in the short term.