SUBSTANCE. Ever since Thales ex plained the universe in terms of water, there has been an almost irresistible tendency among philosophers to explain the unity of intricate assemblages of phenomena in terms of a per manent quasi-material substratum, or, as it is technically known, a substance. The notion of substance runs through the entire pre-Socratic philosophy, and the Platonic realistic hypostasis of the ideas makes of them something very like the substance of the particulars which they em brace. Substance first receives its name and its separation froth form in the philosophy of Aris totle, but this separation is by no means com plete. Substance, or ra iaoeernevovitv, is for Aristotle at once something like the explanatory principles of Thales and the other pre-Socratics, and a form or essence endowed with actual existence. Into the form or essence of a par ticular not all its attributes enter, but Aristotle never makes clear the principle in accordance with which the essential may be separated from the inessential.
The scholastic view of substance is a per petuation of that of Aristotle. The essence aspect of substance was transmitted by the Scholastics to the earlier modern philosophers of the Continent ; though the latter progressively emphasized the function of substance as a sub stratum. Descartes makes mind and matter his two substances, and 'defines substance as that which depends for its existence on God 'alone. God is clearly the ultimate Cartesian substance. This view is modified by Spinoza, though more in terminology than in fact; he holds that God is the one substance, and that mind and matter are two among His infinite number of attrb butes. Whether God is simply the sum of his attributes is left uncertain. The Leibnizian concept of substance is not widely different from that of Descartes, but the number of dif ferent substances — the monads — is multiplied indefinitely.
The British philosophers from the start mixed less of the Aristotelian notion of form and essence with their Substratum-substance than their colleagues on the Continent. Locke followed Descartes in his dualism, but saw that a substratum which is nothing more than a sub stratum can only manifest itself through its appearances, and is unknowable in its inner es sence. Once this became dear, it was obvious that we might remove the substance from the assemblage of appearances overlying it without making any noticeable difference. But 'of two indistinguishable situations it is impossible to assert categorically that one exists and the other does not. Berkeley accordingly discarded sub stance from the realm of matter; he believed, however, that a substantial subject was neces sary for cognition. Hume followed Berkeley in reducing the material world to its phenomena, but saw that the notion of substance furnished as little support for the states of a mind as for the qualities of a material object. Combining this with his unwillingness to admit the exist ence of anything of the nature of a general idea or universal, he was necessarily driven to the opinion that things are mere aggregates of their appearances, which are associated together in a manner quite independent of any inherent re latedness on their part.
The Humian refutation of substance is es sentially valid. The very least which we can demand of a principle of explanation is that it should explain; and the explanation of a group of facts is essentially the more intimate correla tion of them with the rest of our knowledge. After we have been told that the attributes, say, of the material world are unified through their inherence in a material substance, we know just as little of their bearing on one another and on our remaining stock of information as before. Nevertheless, Hume went too far in denying to the mental and material aggregates of phenomena, respectively, all unity other than that which is furnished by the power of ideas to attract associates. Such collections of enti ties as the material world, the world of mind, individual minds, etc., have, prima facie, a very real unity— the unity, namely, that consists in their forming systems. (It may be shown by such means as are used in the article on UNI VERSALS that this unity is not purely illusory). In the post-Humian philosophies, some such no tion of system tends to replace the older con cept of substance.
In the philosophy of Kant the system-notion of the unity of phenomena and the substratum notion are both found, and are almost inextri cably interwoven. Kant retains the old, un knowable substances of Hume under the name of the Things-in-Themselves. While be re gards the existence of these as indubitable, he nevertheless excludes them from any active part in his critical philosophy, in so far as this concerns itself with the pure reason. Within the realm of phenomena, the substances are just such relational, structural complexes as have been described in the last paragraph. Indeed, substance is made a category of relation. The followers of Kant retained this latter phase of his views on substance, and discarded his things — in themselves. They made the entire uni verse their ultimate reality but though they gen erally viewed this in the light of a system, there was not wanting among them the tendency to revert to the substratum idea. However, sub stance, except as the Absolute may be substan tial, was not assigned a fundamental status. Thus in the philosophy of Hegel, substance is but a stage of the cosmic dialectic, not its termi nation.
Though the problem of substance, under its own name, has ceased to play any great part in current philosophical disputes, there are not wanting in the system of the present day enti ties which differ from substances in little but their appellation. Certainly the Bergsonian elan rad serves as a principle of explanation simply by virtue of being a substratum. There is not a little resemblance between the sense data and other particulars of modern atomic realism, serve primarily as pegs on which to hang relations and qualities, and the sub stances which subserve a like function in the philosophy of Locke. See MATTER; SOUL.