What of the relation of natural science and philosophy to idealism? . It is obvious that the very task of the natural sciences necessitates the adoption of conceptions which are funda mentally different in character from those em ployed by idealism; for science is primarily concerned with the relations of particular phe nomena. It is always concerned with the mech anism of the parts, and knows nothing of the ideal purpose or significance of wholes. As Kant said, °where mechanism ceases there ceases also the possibility of scientific explana tion.' This is the ground of the long-standing quarrel betweeit natural science on the one side and idealistic philosophy and religion on the other; the former can interpret the world only in mechanical terms, while the latter must read it in terms of teleology.
The history of thought shows that both these methods of explanation have steadily confronted each other in philosophy. Ideahim and materialism were developed almost simul taneously in Greece — the former by Plato and the latter by Democritus — and the division be tween these opposing principles under one form or another persists until the present day. Al though philosophical systems necessarily vary with the changing intellectual and social condi tions of different periods, yet it remains true, as Fichte said, that in principle °there are and can be only two systems of philosophy, ideal ism and materialism, and that neither one can directly refute the other, since they are con structed upon totally different planes.' Ma terialism, as philosophy, adopts the conceptions and methods of the natural sciences, and differs from the latter only in the greater scope and generality of its problems. It aims to be (in Spencer phrase) °completely unified science.* Idealism, as we have already seen, has a dif ferent problem from that set by science, and states its conclusions in terms that are quite foreign to the latter.
It is usual to distinguish between subjective and objective idealism. The former is an in complete and undeveloped form, and finds its best representative in Berkeley (q.v.). It re solves material existence into a series of ideas in the mind of the individual, holding, in Schopenhauer's phrase, that (the world is my idea.' The proof that it offers for this posi
tion is based mainly on the epistemological thesis that we know and can know nothing but our own ideas. The difficulties and inconsis tencies of this view are now generally recog nized, and the idealism of the present day is known as objective idealism. This does not deny the existence of external reality, but finds implicit in it the same principles of reason and purpose that are present in the individual mind. Indeed, this is true of the great idealistic thinkers of all times — of Plato and Aristotle, no less than of Schelling and Hegel. As a philosophical system, idealism has, of course, to formulate its conclusions in a series of logical propositions and to furnish proofs of their validity. In doing this it does not depend upon the Berkeleian argument mentioned above, but rather proceeds by way of a criticism of the standpoint and categories of natural science. That is, idealistic philosophy attempts to show that the scientific standpoint, when taken as philosophy, i.e., as an ultimate account of the nature of things is in itself incomplete and in consistent and that when the necessary supple mentations and corrections are made it points the way to a view of the world as a rational and purposive system. To make our view of the world completely consistent, many idealists maintain, we are obliged to hold that all its parts are included in an all-embracing system of experience, which finds its unity and its ulti mate reality in the ideals and purposes of an Absolute Mind.
Bibliography.— Compare Plato, especially the (Ph.Tdrus) and 'Republic" (Books VI, VII); Berkeley, 'Principles of Human Knowl edge,' 'Dialogues,' etc.; Webb, T. E., 'The Veil of Isis' (Dublin 1885); Knight, W., (Idealism and Experience in Literature, Art and Life' (in 'Essays jn PhilosophyBoston 1890); Watson, J., 'Christianity andIdealist& (New York 1897) ; Hyde, W. D., 'Practical Idealism' (New York 1897); Brunschwicg, L., (L'idealisme contemporain) (Paris 1905) ; Will mann, (Geschichte des Idealismus) (Brunswick 1894-97).