If we were never to act on our opinions, because those opinions may be wrong, we should leave all our interests uncared for, and all our duties unperformed. An objection which applies to all conduct can be no valid objection to any conduct in particular.

It is the duty of governments, and of individuals, to form the truest opinions they can; to form them carefully, and never impose them upon others unless they are quite sure of being right. But when they are sure (such reasoners may say), it is not conscientiousness but cowardice to shrink from acting on their opinions, and allow doctrines which they honestly think dangerous to the welfare of mankind, either in this life or in another, to be scattered abroad without restraint, because other people, in less enlightened times, have persecuted opinions now believed to be true.