Almost everybody has a conscience, though it may not play a dominating or even very prominent role in his life. To have a conscience is to classify some kinds of action as morally right and others as morally wrong, and to be disposed to do the former and avoid doing the latter. To judge an action as morally right or wrong is not to judge it as advantageous or disadvantageous to the agent; the motive for acting conscientiously cannot be pure self-interest. It is a mark of my thinking an action morally right that I am disposed to do it even though doing it will involve me in a net loss of enjoyment or a net surplus of suffering. A man who is only disposed to do such things as he thinks will increase his happiness in the long run has no conscience. (I do not include among these people those who think that it will be to their ultimate advantage to do what their consciences tell them would be right apart from considerations of ultimate advantage.) Conscience presents itself to a person as a kind of constraint which he cannot evade on the ground that it will be inconvenient to comply with it.