At the present time Tribunals, appointed under an Act of Parliament, are engaged all over England in dealing with claims to exemption from military service based on the ground of “conscientious objection” to taking part directly or indirectly in warlike activities. Now it is no part of the professional business of moral philosophers to tell people what they ought or ought not to do or to exhort them to do their duty. Moral philosophers, as such, have no special information, not available to the general public, about what is right and what is wrong; nor have they any call to undertake those hortatory functions which are so adequately performed by clergymen, politicians, leader-writers, and wireless loudspeakers. But it is the function of a moral philosopher to reflect on the moral concepts and beliefs which he or others have; to try to analyse them and draw distinctions and clear up confusions in connection with them; and to see how they are inter-related and whether they can be arranged in a coherent system. Now there can be no doubt that the popular notions of “conscience” and “conscientious action” are extremely vague and confused. So I think that, by devoting this paper to an attempt to elucidate them, I may succeed in being topical without being impertinent.