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HENRY SIDGWICK, Philosophy, Its Scope and Relations. ellipses. The doctrine of Evolution, on the contrary, as generalised by Spencer and applied to the inorganic matter, to the organic world and to the world of mind, does not help us in the least to understand how the one differs from the other. Sidgwick also repudiates the suggestion that either science or philosophy is concerned merely with phenomena ; both alike aim at a knowledge of realities. Spencer's definition, he proceeds to argue, is defective in another important respect, inasmuch as it seems to include only the positive sciences, thus " neglecting the fundamental dis- tinction between ' what ought to be ' and what actually is or appears" (p. 23). Besides 'theoretical philosophy,' which seeks to unify the positive sciences, room must be made for ' practical philosophy,' which deals with the principles and methods of Ethics and Politics. ' ' The discussion of the ultimate end of right conduct is not concerned with ' the co-existences and sequences of pheno- mena '" (p. 24). It is true, some thinkers endeavour to treat Ethics as a purely descriptive science, but even they cannot avoid looking at it as an art based upon certain positive sciences rather than as itself one of these sciences. Practical Philosophy is "a supreme architectonic study of ultimate ends," subordinating some ends to others and endeavouring to systematise all the elements of human good in ' a theory of rational action as a whole '. It is thus " a study distinct from and in a manner parallel to Philosophy as conceived by Mr. Spencer ; " and " the final and most important task of Philosophy is the problem, of co-ordinating these two divisions of its subject-matter, and connecting fact and ideal in some rational and satisfactory manner" (p. 30). To do this belongs to Meta- physics in that aspect of it which used to be called Eational Theology. Some considerations on this subject are contained, as has been already mentioned, in the concluding chapter and in a Note on the relation of Philosophy to Religion. A long lecture is devoted to the Relation of Philosophy to Psy- chology. The distinction between their respective methods of treating their common subject-matter is clearly drawn on lines generally accepted. Philosophy deals with thoughts and beliefs as true, psychology with the processes by which beliefs, whether true or false, arise in the individual mind. But the chief part of the lecture is devoted to a discussion of the relation of mind to the material world. Mind may be related to matter in two quite dif- ferent ways; a mental fact may have a material process in the brain as its antecedent or concomitant, and it may also have a material thing present to it as an object of cognition. Sidgwick rightly remarks that, in spite of their fundamental distinctness these two relations are sometimes confused. Spinoza's theory of perception might have been cited as an example. In regard to the nature of the first relation which, he remarks, is "in the forefront of specu- lative interest at the present time for educated people generally," Sidgwick objects to the phrase that " mind and nervous action are the subjective and objective faces of the same thing," because it