QUANTITATIVE PLURALISM Quantitative pluralism includes all those theories which hold reality to be made up of a number of relatively independent sub stantial entities, each of which exists, at any rate to some extent, in its own right. Quantitative pluralism is thus sharply contrasted with those forms of singularism or absolutism which regard reality as ultimately consisting of a single individual being, of which the many and diverse elements which seem to exist in the world are no more than mere appearances, qualities, or modes, having no real existence in themselves. This contrast has sometimes been expressed by saying that whereas, according to pluralism, the multitude of entities which appear to find a place in the universe have a "substantival" existence, according to singularism their existence is merely "adjectival" as attributes or aspects of the one real being.
We may classify types of quantitative pluralism according to their doctrine regarding the substance composing the real entities which they postulate. This substance may be material, spiritual (or mental), or it may be neutral in the sense that its essential character is unknown, or, if known in part, cannot be placed definitely in any particular category.
The second kind of neutral pluralism, in which the nature of the ultimate reals is regarded as known, at least in part, hut as not definitely classifiable, has been developed only in compara tively recent years. William James (1842-191o), foremost and
most original of American philosophers, seems to have been the first to have given it clear expression, though he was probably influenced to some extent by the speculations of the German physicist Ernst Mach. James based his belief on what he himself described as a "radical empiricism." He held essentially that the world of which we have knowledge is made up of a number of fundamental elements which may be taken as arranged in different types of patterns or sequences. If the elements are set out in one way we get the kind of structures or series which make up the contents of what we call "minds." Another method of selecting the elements will give the type of arrangements which constitute those entities which we know as material objects or physical events. Yet the elements of a pluralistic universe of this kind are not to be regarded as themselves essentially mental or ma terial—they are of "neutral" stuff. Incidentally James was the first thinker to give the term "pluralism" currency among English speaking philosophers, though in Germany we find it even as early as Wolff, the disciple of the great Leibniz (1646), to whom we shall refer later.
More recently still, a neutral pluralism which in some respects exhibits a strong family likeness to that of William James has been developed in England by Bertrand Russell, who describes his own theory by the name "logical atomism." Russell's pro cedure consists essentially of an exceptionally detailed analysis of the material open to immediate observation, especially the particulars given in sensation and in imagery, followed by an attempt to build up from this material alone constructions cor responding to the fundamental concepts characteristic of physics and of philosophy, or to such among these concepts as analysis may show to be valid within their limits. Russell has applied his method to the analysis both of "mind" and of "matter." Current developments in the theories of some of the American neo-realists seem also to be moving along rather similar lines.