It may be surprising to learn that as far as ethical theory is concerned, the doctrine of an infallible conscience is the product of no less recent a time than the XVIII century. The Conscience-theory is the philosophical property of such men as Butler, Clarke, Kant, Shaftesbury, and Reid, rather than of their predecessors. Thomas Hobbes (1588-1679), who founded critical English ethics, flatly refused to give to the then immature concept of conscience any recognition; indeed, he declared it to be nothing less than a “disease” of the state, and one “of those things that weaken or tend to the dissolution of a commonwealth.” In Chapter XXIX of the “Leviathan,” he states the current notions of conscience: (1) “That every private man is judge of good and evil actions,” and (2) “That whatsoever a man does against his conscience is sin.” Both of these notions Hobbes condemns. “For,” he observes with characteristic sagacity, “a man’s conscience and his judgment is the same thing, and as the judgment so also the conscience may be erroneous.” This emphasis which Hobbes placed upon the untrustworthiness of private ethical judgments was fatal to his purpose. His successors began straightway to reanimate that which he had sought to bury once and for all, and, whether on account of their temperamental antipathy to the intellectualism of Hobbes, or because they were honestly seeking for some valid ethical principle, they asserted, first timidly, and later with a surprising boldness the very thing which Hobbes had sought especially to efface from the docket of ethical discussion. We find this reaction beginning in Shaftesbury (1671-1713). Albeit this author gives a minor place in his ethical theory to the notion of a “moral sense,” or rational, reflex affection which approves only socially beneficial actions, yet the positive emphasis which he puts upon it is nevertheless significant. The affirmation proved to be contagious, for those who followed Shaftesbury immediately elevated conscience to a central position in their systems. We refer here to Butler, Clarke, Kant, and Reid, who are known as intuitionists. According to Butler (1692-1752), conscience is a “principle of reflection” and not a mere _feeling_. And this principle of reflection is for him a natural or inherent property of man’s mind. It is the principle by which a man “approves or disapproves his heart, temper, and actions”; it is a faculty which “tends to restrain men from doing mischief to each other, and leads them to do good.” Be it noted here that Butler says nothing about the so-called infallibility of conscience, nor does he argue that it must be the same for all persons. Moreover, he gives a somewhat analytical definition of it, and is willing to grant that its function is utilitarian.