Positivism is the view that the only way to obtain knowledge of the world is by means of sense perception and introspection and the methods of the empirical sciences. Positivists believe that it is futile to attempt to deduce or demonstrate truths about the world from alleged self-evident premisses that are not based primarily on sense perception. They consider, on the contrary, that knowledge of things can only be advanced by framing hypotheses, testing them by observation and experiment, and reshaping them in the light of what these reveal. Thus they regard metaphysics, in so far as it is the effort to find out about the world by methods other than those employed in the empirical sciences, as a hopelessly misdirected activity. The method of hypothesis, they hold, is applicable to any field of factual enquiry, although they admit that differences of subject-matter may call for very considerable variations of emphasis. Such variations, however, important though they be, are, on their view, matters of detail, and do not detract from the essential sameness of the effective method. This method was first consciously analysed by reference to the sciences of nature, where its use has led to impressive results both in the theoretical and practical sphere.

“It is almost impossible for a working neurologist to think clearly about the functions of the highest centres because the counters of thought, the words he must employ—are often of psychological origin and for the most part meaningless.”

In his book The Right and the Good Professor W. D. Ross states a theory that ethics is concerned with two distinct conceptions which are logically quite independent of each other and must not be confused: the right, viz. the act which we are under an obligation to do irrespective of our motives, and the morally good, viz. the good motives, desires and so on, irrespective of what actions they lead us to. In a later book, Foundations of Ethics, he repeats this theory somewhat altered and enlarged. Professor Broad says about the first book that it is “the most important contribution to ethical theory made in England for a generation,” and for the second book he proposes the nickname “the righter and the better.”

There are, I think, three distinct senses in which Rousseau uses the term “general will.” He means by it, as the nineteenth century Idealists used to point out, something very like Kant's “good will,” which all men have in common and which cannot conflict with itself. But he also means, quite as often, the Utilitarian compromise, The mean between divergent interests which takes account of all of them and satisfies as many as possible. And, thirdly, he means something like the “culture pattern” of the modern anthropologists. I want to show that Green inherits this ambiguity, and that his argument in the Principles of Political Obligation is plausible only because he does not distinguish between these three meanings of “general will.”