[158]. Compare, e.g., the first of the arguments for immortality in Plato’s Phædo, p. 70 ff., and the remark in the Republic, with obvious reference to this argument, that the “number of souls is always the same” (611A). In Plato the doctrine is pretty certainly of Orphic provenance. Compare also the cyclic alternation of death and life in Heracleitus, the (Orphic) cycle of births of Empedocles, that of the Stoics, and in the modern world, to take only one instance, the “eternal recurrence” of Nietzsche.
[159]. The same phenomenon of the formation of a new individuality within the limits of an already existing one, is illustrated by the familiar facts of the moral conflict between the “higher” and “lower” self.
[160]. Compare Royce, The World and the Individual, Second Series, p. 305 ff., where a view of this kind is worked out in some detail. Prof. Royce’s second volume unfortunately came into my hands too late to enable me to make all the use of it I could have wished; the same is the case with Mr. Underhill’s essay on “The Limits of Evolution” in Personal Idealism.
CHAPTER VI
THE LOGICAL CHARACTER OF DESCRIPTIVE
SCIENCE
[§ 1.] Scientific description may be contrasted with philosophical or teleological interpretation, but the contrast is not absolute. [§ 2.] The primary end of all scientific description is intercommunication with a view to active co-operation. Hence all such description is necessarily restricted to objects capable of being experienced in the same way by a plurality of individuals. [§ 3.] A second end of scientific description is the economising of intellectual labour by the creation of general rules for dealing with typical situations in the environment. In the course of evolution this object becomes partially independent of the former. [§ 4.] From the interest in formulating general rules arise the three fundamental postulates of physical science, the postulates of Uniformity, Mechanical Law, and Causal Determination. [§ 5.] The mechanical view of physical Nature determined by these three postulates is systematically carried out only in the abstract science of Mechanics; hence the logical completion of the descriptive process would mean the reduction of all descriptive science to Mechanics. That the chemical, biological, and psychological sciences contain elements which cannot be reduced to mechanical terms, is due to the fact that their descriptions are inspired by æsthetic and historical as well as by primarily “scientific” interests. [§ 6.] The analysis of such leading concepts of mechanical Physics as the Conservation of Mass and of Energy shows them to have only relative validity.
§ 1. In its general outlines our interpretation of the significance of the physical order is now complete. We have seen reason to hold that in that order we have the appearance to our human senses of a great system or complex of systems composed of purposive sentient beings, whose interests are for the most part so widely removed from our own as to preclude all direct intercourse, but who are nevertheless historically connected with ourselves by that unceasing process of the development of new forms of individual interest which we know empirically as the evolution of life and intelligence on our planet. As we have tried throughout the four preceding chapters to show in detail, there is no real inconsistency between this general interpretation of the meaning of the physical order and the working assumptions of our various empirical sciences. At the same time it is obvious that in executing the task of the detailed description and calculation of the phenomenal course of events, the empirical sciences, while not rejecting such a metaphysical interpretation, ignore it; and the more conscientiously they exclude from their programme all amateur excursions into extraneous metaphysical speculation, the more thoroughly is the work of description and mathematical formulation done. It seems advisable, therefore, to conclude our brief sketch of the principles of Cosmology with a short discussion of the nature of the limitations imposed on empirical science, by the special character of the objects it sets before it, and of the way in which the existence of these limitations is revealed by analysis of the most general concepts of the empirical sciences themselves.
It is important, in the first place, to be quite clear as to the sense in which we speak of description as the work of the empirical sciences, and as to the meaning of the contrast between such description and a philosophical interpretation of existence. In this connection there are two points which seem to call for special and repeated emphasis. (1) The contrast between interpretation and description is not an absolute one. Complete description would of itself be something more than mere description, and would pass into philosophical interpretation. Thus a significant purposive movement is not adequately described when, e.g., its direction, velocity, momentum, and duration have been assigned. The complete description of such a movement would require the recognition of its meaning for the being executing it as a step in the realisation of a craving or a design, and would thus merge in what we have called philosophical interpretation. So generally, if all existence is ultimately experience and all experience essentially teleological, such description as can be distinguished from interpretation must always be incomplete from the logical standpoint, though adequate to fulfil certain special purposes.
(2) The descriptions of science, again, must be carefully distinguished from such descriptions as can be effected by the mere multiplication of unanalysed sensible detail. Scientific description, it must be remembered, is always description undertaken with a view to the calculation and prediction of the course of events. This implies that it must be description in general terms, and, wherever possible, by the aid of mathematical analysis. Natural processes are described by the empirical sciences which deal with them, not in their concrete individual detail, but only in so far as they exhibit certain uniform aspects permitting of reduction to formulæ suitable for calculation. Such description is frequently spoken of as explanation, and is expressly contrasted by this difference in nomenclature with the mere accumulation of sensible detail. We must not, however, allow the difference in question to blind us to the essentially descriptive character of all scientific hypotheses. It is sometimes urged that scientific explanation must differ in its logical character from description, because the “substance,” “agencies,” and “media,” in terms of which explanation is couched, are largely of a kind inaccessible to sense-perception. It must be remembered, however, that hypotheses as to such imperceptible objects are only valuable so far as they serve as connecting-links by which we may calculate sensible events from sensible data. Whatever intermediate links empirical science may find it useful to assume, it invariably takes the sensible occurrences of the phenomenal physical order as the starting-point, and again as the goal of its inferences.[[161]] All its hypothetical constructions are thus subservient to the main interest of the accurate description of the course of sensible events. The only kind of “explanation” which can be reasonably contrasted, in respect of its logical character, with description is teleological interpretation, and even here the contrast, as we have seen, is not final.
§ 2. We have to ask, then, what is the object at which scientific descriptions aim? What purpose do they seek to fulfil, and how does the essential character of this purpose determine the logical character of the descriptive process? Now, it is at once evident that all description has for its immediate object one or other of two practical ends, which are so closely connected as to be ultimately coincident. Historically, it is beyond a doubt that the original purpose of all description of physical events was intercommunication with a view to social co-operation. I have already referred to this function of description with special reference to the use of causal descriptions in science, but may conveniently deal with the same point rather more fully and in a more general way here.