I then urged that the method of science is to frame ideal constructions; that in its departmental studies it extracts from the manifold of phenomena just those essentials which are necessary for its specific synthesis, and even these it reduces to their simplest expression; its generalisations are inevitably schematic and abstract; they cannot include all the detail of natural occurrences; but the system so elaborated has value because it enables the man of science to interpret the varied situations to which the ideal scheme is applicable. Throughout its interpretations it deals with antecedence, coexistence, and sequence as they are extracted in schematic form from the data which are afforded to experience. On the basis of observation physics, having translated these data into terms susceptible of mechanistic treatment, builds in thought a configuration of range and delicacy often far outrunning the limits of observation, a configuration undergoing slow or rapid changes often in no way susceptible of direct measurement. The antecedent configuration of any given moment is regarded as the condition, or the scientific cause, of the subsequent configuration of the moment that follows. But with regard to any motive power or agency, with regard to any force as the underlying Cause of motion, with regard to any source or origin of the changes of configuration, it is and must remain, as science, silent. Such Causation lies beyond its ken. It does not enter into the scheme of scientific interpretation; it is no part of the assumptions of naturalism; if entertained at all it must be regarded as a metaphysical postulate. As Berkeley long ago said in his Siris (Sec 231), " The laws of attraction and repulsion are to be regarded as laws of motion, and these only as rules or methods observed in the production of natural effects, the efficient and final causes whereof are not of mechanical consideration. Certainly, if the explaining of a phenomenon be to assign its proper efficient and final cause, it should seem the mechanical philosophers never explained anything; their province being only to discover the laws of nature, that is, the general rules and methods of motion, and to account for particular phenomena by reducing them under, or showing their conformity to, such general rules".
But just as the analysis of our daily experience, in showing its close and intimate dependence in the last resort on perception, only brings into greater prominence the need of a supplementary postulate, that there is a purpose which renders it rational-nay, more, serves to disclose the fact that " there are notions embedded in experience, which experience cannot justify or explain " in terms of antecedence and sequence—so, too, does a consideration of the ideal constructions of science lead us to inquire how it is that these human contrivances do so helpfully symbolise what is most interesting in a world which is at any rate independent of individual perception so far as it has social validity. In brief, granting that the reality of objective experience is dependent on correspondence of reference for all normal human percipients, how is this correspondence secured, and how comes it that our rational constructions enable us to interpret not only our own experience but that of others?
Granting to naturalism that the universe of phenomena is ideally explicable in terms of configurations undergoing changes which conform to rule, the fact remains that there are different types of configuration. So long as we are dealing with a given order all the changes are in conformity with the rules which hold good within that order. But when we pass from one order to another new rules obtain. There are thousands and tens of thousands of cases in the world of inorganic nature in which new modes of acceleration, involving new properties, come suddenly upon the scene—properties which, with our existing knowledge, we could not have foretold. Science must accept these new properties as data afforded to experience. All that we can do is to trace, if possible, the antecedent conditions of their appearance. Protoplasm exhibits characteristic properties; there are specific types of physiological acceleration; there are modes of selective synthesis elsewhere unknown. And the antecedent conditions of the natural origin of protoplasm are still and may long remain matters of conjecture. But it is questionable whether we can here apply the old adage: De non apparentibus et non existentibus eadem est ratio. With the acceptance of such a principle science commits intellectual suicide. Vitalism, so far as it implies an alien influx into nature, is sheer metaphysics, and so far as it restricts the operation of some causal agency to the phenomena of life is bad metaphysics. I need hardly say, however, that it is no part of my thesis to deny in the genesis of protoplasm the manifestation of an underlying purpose. But the manifestation is not restricted to the living cell; it is omnipresent throughout the universe of phenomena. It permeates the whole structure of our experience, both in its objective and subjective reference. And in the latter reference it is postulated in the well-known dictum of Descartes, Cogito, ergo sum.
But on the assumption that there is a metaphysical basis for the cogito, my own system of related mental sequences is just the one bit of experience in all the world where the nature of the underlying purpose which pervades the universe can stand revealed if it can be revealed at all. The same cause which drives the planets on their course, which sweeps the storm over land and sea, which fashions the frost patterns on the window-pane, which gives sensitiveness to the amoeba and intelligence to the elephant, works in the brain and thought of man. And here alone, in the underlying depths of his own personality, has he an intuition of its nature. If, however, he feels justified in believing that, in the purpose which unifies, directs, and determines the course of his own experience, there is real casual agency, he can not escape the conviction that it is in constant relation to a wider purpose, of the same order of being, but free from his own petty limitations and imperfections.
In the view which I have attempted to set forth, a cardinal feature is that our knowledge is reached by a process of ideal construction. We thus, and only thus, attain to such cognisance of the realities of existence as is possible for us within the limits of human experience. That there is a purpose in nature in relation to our own purpose is an ideal construction: as such it is to be accepted or rejected. But if it be only in the intimations of our own personality that we have any experience of the order of being to which causal activity belongs, our conception of the purpose in nature is so far anthropomorphic. All conceptions in terms of human experience must be anthropomorphic, though we may impatiently strive to rid our thought of this fundamentally ineradicable characteristic. Of such a type too is, and must inevitably be, for religious thought, the conception of God. And in every form of Monotheism this characteristic is emphasised in the conception of God as personal. For religious thought, God—God in relation to human experience, God in so far as we can know Him—is an ideal construction. For the purpose of that thought the ideal construction is specialised, and differs from that of the Absolute as a philosophical conception. And part of this specialisation is the emphasis laid on personality. It is not for me to trespass on the province of the theologian or attempt to show in what ways our ideal construction in the field of religion differs from that which the metaphysician formulates, in his own domain, as the universal cause beneath phenomenal presentations. The two differ in so far as they belong to different universes of experience. The God of Monotheism and the unknowable of a philosophic pantheism, so called, are not the same ideal construction. Into such questions, however, I cannot enter. My point is that, for those who accept the realities of religion as a valid type of human experience, the turning-point of historic evolution—the turning-point of individual development— is that at which man creates God in his own image and sees that He is good. If to some this inversion of the Hebrew text savours of irreverence, they should bear in mind that my thesis has been that it is by such a process of ideal construction we reach, in other fields of thought and experience, the highest and best products of conception, and thus come into the closest touch to which we can attain, with the realities and the verities of existence. Thus only do we approximate to the truth that is independent of us severally and individually.