Let us discuss this matter impersonally, without reference to our own opinions and without reference to the evidence for or against their truth. I am not speaking now of those who hold all these ideas to be certainly true, or highly probable, and who at the same time incidentally insist on the great usefulness of such ideas in confirming morality and producing virtuous types of character. With such persons, of course, there is no question of a dual doctrine. They entertain certain convictions themselves, and naturally desire to have their influence extended over others. The proposition which we have to consider is of another kind. It expresses the notions of those who--to take the most important kind of illustration--think untrue the popular ideas of supernatural interference in our obscure human affairs; who think untrue the notion of the prolongation of our existence after death to fulfil the purpose of the supernatural powers; or at least who think them so extremely improbable that no reasonable man or woman, once awakened to a conviction of this improbability, would thenceforth be capable of receiving effective check or guidance from beliefs, that would have sunk slowly down to the level of doubtful guesses. We have now to deal with those who while taking this view of certain doctrines, still declare them to be indispensable for restraining from anti-social conduct all who are not acute or instructed enough to see through them. In other words, they think error useful, and that it may be the best thing for society that masses of men should cheat and deceive themselves in their most fervent aspirations and their deepest assurances. This is the furthest extreme to which the empire of existing facts over principles can well be imagined to go. It lies at the root of every discussion upon the limits which separate lawful compromise or accommodation from palpable hypocrisy.