The process of reduction does not stop even here. For physical and chemical processes are only really understood when they can be resolved into the simplest processes of movement in general, when all qualitative changes can be traced hack to purely quantitative phenomena, when, finally, in the mechanics of the great masses, as well as of the infinitely small atoms, everything becomes capable of expression in mathematical terms.
But naturalism of this kind is by no means pure natural science; it consciously and deliberately oversteps in speculation the bounds of what is strictly scientific. In this respect it bears some resemblance to the nature-philosophy associated with what we called the first type of naturalism. But its very poverty enables it to have a strictly defined programme. It knows exactly what it wants, and thus it is possible to argue with it. The religious conception of the world must come to an understanding with it, for it is quite obvious that the more indifferent this naturalism is to everything outside of itself, and the less aggressive it pretends to be, the more does the picture of the world which it attempts to draw exert a cramping influence on religion. Where the two come into contact we shall endeavour to make clear in the following pages.
The fundamental convictions of naturalism, its general tendencies, and the points of view which determine its outlook, are primarily related to that order of facts which forms the subject of the natural sciences, to “Nature.” It is only secondarily that it attempts to penetrate with the methods of the natural sciences into the region of the conscious, of the mind, into the domain that underlies the mental sciences, including history and the æsthetic, political, and religious sciences, and to show that, in this region as in the other, natural law and the same principles of interpretation obtain, that here, too, the “materialistic conception of history holds true, and that there is no autonomy of mind.”
The interests of religion here go hand in hand with those of the mental sciences, in so far as these claim to be distinct and independent. For the question is altogether one of the reality, pre-eminence, and independence of the spiritual as opposed to the “natural.” Occasionally it has been thought that the whole problem of the relations between religion and naturalism was concentrated on this point, and the study of nature has been left to naturalism as if it were indifferent or even hopeless, thus leaving a free field for theories of all kinds, the materialistic included. It is only in regard to the Darwinian theory of evolution and the mechanical theory of the origin and nature of life, and particularly in regard to the relatively unimportant question of “spontaneous generation” that a livelier interest is usually awakened. But these isolated theories are only a part of the “reduction,” which is characteristic of naturalism, and they can only be rightly estimated and understood in connection with it. We shall turn our attention to them only after we have carefully considered what is fundamental and essential. But the idea that religion may calmly neglect the study of nature as long as naturalism leaves breathing-room for the freedom and independence of mind is quite erroneous. If religion is true, nature must be of God, and it must bear tokens which allow us to interpret it as of God. And such signs are to be found. What we shall have to say in regard to them may be summed up in the following propositions:—