462 HISTORY OF PHILOSOPHY from the existence of different degrees of wisdom (170), and from the existence of experts (178-179), it is based upon the common interpretation of common experiences. Men do have dreams and suffer from illusions: when they do so they are deceived and their opinions are false: therefore Protagoras is wrong. Similarly, philosophers do talk about universal moral natures: these are demonstrably not the same as particular local conventions: therefore Protagoras is wrong. Plato is saying, "Here is the situation as we know it: we have philosophers on the one hand and politicians and lawyers on the other. They are clearly and obviously in different categories, and the objects with which each group concerns itself are clearly different. But if Protagoras were right this could not be the case. There would be only one set of things to talk about, and the lawyer, the politician, and the philosopher would merge into one.''s All the arguments in this group can be challenged in much the same way, methodologically speaking. In each case we may properly attack the common-sense assumptions on which the argument is based--in the first instance the assumption that dreams and so on can properly be called 1a/se, and in the present case the assumption that philosophers are talking about something real.9 In that sense the digression, like the arguments among which it is set, is a "popular" and not a "philosophical" refutation of the thesis under discussion, though it contains much that was, to Plato, of philosophical interest and importance. And in its introduction of "universals" as a proper sphere of study, it of course prepares the way for the final, philosophical, and arguably conclusive refutation at 184--186. ANDREW BARKER University of Warwick BUTLER ON CORRUPT CONSCIENCE I. A PROBLEM FOR BUTLER'S ETHICS Bishop Butler's answer to the question What ought one to do? is this: Do what your conscience tells you to do; let your conscience be your guide. If something is the prudent thing to do, then that is one reason for doing it. If a certain course of action is benevolent, then that is another reason for doing it. However, if one's conscience tells one to do something, then that is not merely a reason for doing it but is a morally conclusive reason for doing it. This is what Butler means when he says that conscience has supreme moral authority, albeit it often lacks the necessary psychological power. In support of the above claims consider the following passages: But there is a superior principle of reflection or conscience in every man, which distinguishes between the internal principles of his heart, as well as his external actions: s In the Republic, of course, Plato envisages just such a merger, but one achieved not by bringing the philosopher "down" to the level of the politician, but by bringing the politician "up" to the level of the philosopher. 9 We need not see this as an instance of the special Eleatic argument (if I think something, there must be something for me to think, etc.), which appears later in the Theaetetus (187 ft.) and in the Sophist (236 ft.). The appeal may be much more straightforwardly "popular": "here are all these wise men spending their lives talking about universal justice, goodness, and so on: surely they can't all be talking about nothing at all?" NOTES AND DISCUSSIONS 463 which passes judgment upon himself and them; pronounces determinately some actions to be in themselves just, right, good; others to be in themselves evil, wrong, unjust: which, without being consulted, without being advised with, magisterially exerts itself, and approves or condemns him, the doer of them, accordingly.... 1 It is by this faculty, natural to man, that he is a moral agent, that he is a law to himself: but this faculty, I say, not to be considered merely as a principle in his heart, which is to have some influence as well as others; but considered as a faculty in kind and in nature supreme over all others, and which bears its own authority of being so.2 The fact of erroneous conscience has...