5. If we grant that, wherever there is one constant predicate belonging to many particulars, or wherever there is stable and trustworthy cognition, in all such cases a Self-existent Universal Correlate extra rem is to be assumed, we shall find that this applies not merely to Substances or Essences, but also to the other Categories — Quality, Quantity, Relation, &c. But hereby we exclude the possibility of participation in them by Particulars; since from such participation the Particular derives its Substance or Essence alone, not its accidental predicates. Thus the Self-existent Universal Dyad is eternal: but a particular pair, which derives its essential property of doubleness from partaking in this Universal Dyad, does not at the same time partake of eternity, unless by accident. Accordingly, there are no Universal Ideas, except of Substances or Essences: the common name, when applied to the world of sense and to that of cogitation, signifies the same thing — Substance or Essence. It is unmeaning to talk of anything else as signified — any other predicate common to many. Well then, if the Form of the Universals and the Form of those Particulars that participate in the Universals be the same, we shall have something common to both the one and the other, so that the objection called “The Third Man� will become applicable, and a higher Form must be postulated. But, if the Form of the Universals and the Form of the participating Particulars, be not identical, then the same name, as signifying both, will be used equivocally; just as if you applied the same denomination man to Kallias and to a piece of wood, without any common property to warrant it.
6. But the greatest difficulty of all is to understand how these Cogitable Universals, not being causes of any change or movement, contribute in any way to the objects of sense, either to the eternal or to the perishable; or how they assist us towards the knowledge thereof, being not in them, and therefore not their substance or essence; or how they stand in any real relation to their participants, being not immanent therein. Particulars certainly do not proceed from these Universals, in any intelligible sense. To say that the Universals are archetypes, and that Particulars partake in them, is unmeaning, and mere poetic metaphor. For where is the working force to mould them in conformity with the Universals? Any one thing may be like, or may become like, to any other particular thing, by accident, or without any regular antecedent cause to produce such assimilation. The same particular substance, moreover, will have not one universal archetype only, but several. Thus, the same individual man will have not only the Self-animal and the Self-biped, but also the Self-man, as archetype. Then again, there will be universal archetypes, not merely for particular sensible objects, but also for Universals themselves; thus the genus will be an archetype for its various species; so that the same which is now archetype will, under other circumstances, be copy.
7. Furthermore, it seems impossible that what is Substance or Essence can be separate from that whereof it is the substance or essence. How then can the Universals, if they be the essences of sensible things, have any existence apart from those sensible things? Plato tells us in the Phædon, that the Forms or Universals are the causes why particulars both exist at all, and come into such or such modes of existence. But even if we assume Universals as existing, still the Particulars participant therein will not come into being, unless there be some efficient cause to produce movement; moreover, many other things come into being, though there be no Universals correlating therewith, e.g. a house, or a ring. The same causes that were sufficient to bring these last into being, will be sufficient to bring all particulars into being, without assuming any Universals extra rem at all.
8. Again, if the Universals or Forms are Numbers, how can they ever be causes? Even if we suppose Particulars to be Numbers also, how can one set of Numbers be causes to the others? There can be no such causal influence, even if one set be eternal, and the other perishable.[17]
[17] Aristot. Metaph. A. p. 991, b. 13. Several other objections are made by Aristotle against that variety of the Platonic theory wherein the Ideas were commuted into Ideal Numbers. These objections do not belong to the controversy of Realism against Nominalism.
Out of the many objections raised by Aristotle against Plato, we have selected such as bear principally upon the theory of Realism; that is, upon the theory of Universalia ante rem or extra rem — self-existent, archetypal, cogitable substances, in which Particulars faintly participate. The objections are not superior in acuteness, and they are decidedly inferior, in clearness of enunciation, to those that Plato himself produces in the Parmenides. Moreover, several of them are founded upon Aristotle’s point of view, and would have failed to convince Plato. The great merit of Aristotle is, that he went beyond the negative of the Parmenides, asserted this new point of view of his own, and formulated it into a counter-theory. He rejected altogether the separate and exclusive reality which Plato had claimed for his Absolutes of the cogitable world, as well as the derivative and unreal semblance that alone Plato accorded to the sensible world. Without denying the distinction of the two, as conceivable and nameable, he maintained that truth and cognition required that they should be looked at in implication with each other. And he went even a step farther, in antithesis to Plato, by reversing the order of the two. Instead of considering the Cogitable Universals alone as real and complete in themselves, and the Sensible Particulars as degenerate and confused semblances of them, he placed complete reality in the Sensible Particulars alone,[18] and treated the Cogitable Universals as contributory appendages thereto; some being essential, others non-essential, but all of them relative, and none of them independent integers. His philosophy was a complete revolution as compared with Parmenides and Plato; a revolution, too, the more calculated to last, because he embodied it in an elaborate and original theory of Logic, Metaphysics, and Ontology. He was the first philosopher that, besides recognizing the equivocal character of those general terms whereon speculative debate chiefly turns, endeavoured methodically to set out and compare the different meanings of each term, and their relations to each other.
[18] Aristotle takes pains to vindicate against both Plato and the Herakleiteans the dignity of the Sensible World. They that depreciate sensible objects as perpetually changing, unstable, and unknowable, make the mistake (he observes) of confining their attention to the sublunary interior of the Kosmos, where, indeed, generation and destruction largely prevail. But this is only a small portion of the entire Kosmos. In the largest portion — the visible, celestial, superlunary regions — there is no generation or destruction at all, nothing but permanence and uniformity. In appreciating the sensible world (Aristotle says) philosophers ought to pardon the shortcomings of the smaller portion on account of the excellences of the larger; and not condemn both together on account of the smaller (Metaphys. Γ. v. p. 1010, a. 30).
However much the Ontology of Aristotle may fail to satisfy modern exigencies, still, as compared with the Platonic Realism, it was a considerable improvement. Instead of adopting Ens as a self-explaining term, contrasted with the Generated and Perishable (the doctrine of Plato in the Republic, Phædon, and Timæus), he discriminates several distinct meanings of Ens; a discrimination not always usefully pursued, but tending in the main towards a better theory. The distinction between Ens potential, and Ens actual, does not belong directly to the question between Realism and Nominalism, yet it is a portion of that philosophical revolution wrought by Aristotle against Plato — displacement of the seat of reality, and transfer of it from the Cogitable Universal to the Sensible Particular. The direct enunciation of this change is contained in his distinction of Ens into Fundamental and Concomitant (συμβεβηκός), and his still greater refinement on the same principle by enumerating the ten varieties of Ens called Categories or Predicaments.[19] He will not allow Ens (nor Unum) to be a genus, partible into species: he recognizes it only as a word of many analogous meanings, one of them principal and fundamental, the rest derivative and subordinate thereto, each in its own manner. Aristotle thus establishes a graduated scale of Entia, each having its own value and position, and its own mode of connexion with the common centre. That common centre Aristotle declared to be of necessity some individual object — Hoc Aliquid, That Man, This Horse, &c. This was the common subject, to which all the other Entia belonged as predicates, and without which none of them had any reality. We here fall into the language of Logic, the first theory of which we owe to Aristotle. His ontological classification was adapted to that theory.
[19] In enumerating the Ten Categories, Aristotle takes his departure from the Proposition — Homo currit — Homo vincit. He assumes a particular individual as subject; and he distributes, under ten general heads, all the information that can be asked or given about that subject — all the predicates that can be affirmed or denied thereof. [See [Ch. iii.], especially [p. 73], seq.]
As we are here concerned only with the different ways of conceiving the relation between the Particular and the Universal, we are not called on to criticize the well-known decuple enumeration of Categories or Predicaments given by Aristotle, both in his treatise called by that name and elsewhere. For our purpose it is enough to point out that the particular sensible Hoc Aliquid is declared to be the ultimate subject, to which all Universals attach, as determinants or accompaniments; and that, if this condition be wanting, the unattached Universal cannot rank among complete Entia. The subject or First Substance, which can never become a predicate, is established as the indispensable ultimate subject for all predicates; if that disappears, all predicates disappear along with it. The Particular thus becomes the keystone of the arch whereon all Universals rest. Aristotle is indeed careful to point out a gradation in these predicates: some are essential to the subject, and thus approach so near to the First Substance that he calls them Second Substances; others, and the most in number, are not thus essential; these last are Concomitants or Accidents, and some of them fall so much short of complete Entity that he describes them as near to Non-Entia.[20] But all of them, essential or unessential, are alike constituents or appendages of the First Substance or Particular Subject, and have no reality in any other character.