If it be said in reply, that these men tacitly assent in their minds to what their practice contradicts, Locke answers, first, that men’s actions must be held as the best interpreters of their thoughts; and if many men’s practices, and some men’s open professions, have been opposed to these principles, we cannot conclude them to be Innate.  Secondly, It is difficult for us to assent to Innate Practical Principles, ending only in contemplation.  Such principles either influence our conduct, or they are nothing.  There is no mistake as to the Innate principles of the desire of happiness, and aversion to misery; these do not stop short in tacit assent, but urge every man’s conduct every hour of his life.  If there were anything corresponding to these in the sense of Right and Wrong, we should have no dispute about them.

3.  There is no Moral rule, that may not have a reason demanded for it; which ought not to be the case with any innate principle.  That we should do as we would be done by, is the foundation of all morality, and yet, if proposed to any one for the first time, might not such an one, without absurdity, ask a reason why?  But this would imply that there is some deeper principle for it to repose upon, capable of being assigned as its motive; that it is not ultimate, and therefore not innate.  That men should observe compacts is a great and undeniable rule, yet, in this, a Christian would give as reason the command of God; a Hobbist would say that the public requires it, and would punish for disobeying it; and an old heathen philosopher would have urged that it was opposed to human virtue and perfection.

Bound up with this consideration, is the circumstance that moral rules differ among men, according to their views of happiness.  The existence of God, and our obedience to him, are manifest in many ways, and are the true ground of morality, seeing that only God can call to account every offender; yet, from the union of virtue and public happiness, all men have recommended the practice of what is for their own obvious advantage.  There is quite enough in this self-interest to cause moral rules to be enforced by men that care neither for the supreme Lawgiver, nor for the Hell ordained by him to punish transgressors.

After all, these great principles of morality are more commended than practised.  As to Conscience checking us in these breaches, making them fewer than they would otherwise be, men may arrive at such a conscience, or self-restraining sentiment, in other ways than by an innate endowment.  Some men may come to assent to moral rules from a knowledge of their value as means to ends.  Others may take up the same view as a part of their education.  However the persuasion is come by, it will serve as a conscience; which conscience is nothing else than our own opinion of the rectitude or pravity of our actions.

How could men with serenity and confidence transgress rules stamped upon their inmost soul?  Look at the practices of nations civilized and uncivilized; at the robberies, murders, rapes of an army sacking a town; at the legalized usages of nations, the destruction of infants and of aged parents for personal convenience; cannibalism; the most monstrous forms of unchastity; the fashionable murder named Duelling.  Where are the innate principles of Justice, Piety, Gratitude, Equity, Chastity?