An Aristotelian realist -- and Hartshorne is one -- holds that the problem of universals has to do with accounting for how similarities and identities develop in the concrete flow of events. Along with Peirce and Weiss, Hartshorne holds that particulars are completely determinate, and therefore can only be past events, and that universals are somewhat indeterminate, and can therefore characterize only the future. ‘When universals are abstracted from the concrete particulars, characters are derived from the past as vague potentialities for future realization. In this sense, all potentiality derives from concrete actuality, an Aristotelian thesis. This makes sense of Hartshorne’s contention in his chapter "Abstraction the Question of Nominalism," that the novel forms emergent in a creative event are not determinate before the event but become determinate by decision in the event; to deny this is to deny any real meaning to creativity. For the Aristotelian position, the real problem is to explain how forms get into the temporal process, and it makes sense to say that they emerge.The Aristotelian story of how the universals come to be relevant to and function in the process of concrete events is compatible with the Platonic account of how change depends on its formal possibility. Platonists like Whitehead provide theories about the ingression of forms in things through prehension of the past as well as theories about the constitution of formal possibility as such in terms of eternal objects, the divine primordial decision, and the like. Whitehead unfortunately failed to emphasize the fact that eternal objects are norms, and had to say that eternal objects are empty except insofar as they are graded as relevant to the world by God. But his theory of propositional valuation is congenial for interpreting the eternal objects as norms, given determinate shape by the components they must measure together.What sense does it make to say a universal is contained in a concrete particular? It is clear that an instance of a universal can be so contained. (Perhaps it is better to say that the concrete particular itself is an instance of the universal, and perhaps of several other universals also. Or perhaps the preferable language is to speak of the particular as instancing the universal.) In what sense is the universal contained in the particular when the latter is an instance of it? To this kind of question, two kinds of answers falling within the "realist" camp have been given. They can be called, for historical reasons, Aristotelian realism and Platonic realism.An emergent universal is nonsense to a Platonist, however. For a Platonist the only things that can change or come to be axe those essentially related to the existential temporal process, e.g. things that make decisions -- events, and the like. A universal is that by which we measure change and diversity as well as continuity. As Plato argued in the Parmenides, instances of forms can be alike or similar, but there is no similarity between the instances and the universal itself; otherwise you get into a third-man argument. So in a sense universals are not things, desiccated shapes imaging or being imaged in concrete particulars; rather they are norms, indeterminate in themselves, but determinate as measures of how the particular components of a complexity ought to go together. For a Platonist it is possible to abstract the pattern of a concrete thing and call it the form of the thing; but this is a shortcut to speaking the truth. The pattern is no more the universal than is the concrete thing so patterned; the only advantage of the pattern is that we can imagine it to be found in other particulars. But as Hartshorne. Weiss and others so well point out, concrete particulars always differ in their overall patterns; in fact, difference in individual identity comes down to difference in determinate pattern. The universal or form itself is the value finding embodiment in the world in "a certain way."
Two particulars are alike because the same value measures their similar components with a pattern ingredient in both. Their components are similar by virtue of being measured by the same component values, and so on down. The causal reason why things are similar may well be that they both prehend the same past events, and therefore have the same components to be measured in their own subjective forms. But the metaphysical reason for the possibility of similarity and difference, according to the Platonic realist, consists in the fact that value can be ingredient with multiplicity in different parts of a process only by virtue of different structures or patterns. As a Platonist would say, the structured world is a compromise between chaos and the Good. There is ultimately only one real universal, the Form of the Good. We distinguish different forms because there are similar patterns of complexities recurring and therefore exhibiting similar patterns, each one of which seems to name a universal.
Whereas the Aristotelian story is about how universals appear in the historical process -- and in that sense they do seem to emerge -- the Platonic story is about how determinateness is possible. Regarding the latter, a decision to make pattern X ingredient in oneself as a measure of components a, b, c, is not possible unless X is indeed a way of measuring a, b, c, . . . together. Whether a, h, c,.. are measurable by X is totally irrelevant to whether a, b, c, . . . are in fact actual in the temporal process. The relation between the pattern in which the form measures the pattern’s components and the patterns of the components is quite eternal. Of course, if the components are never actualized in the real process, that relation is totally irrelevant to the course of events. But whether universals are relevant to the world makes no difference to the universals, conceived in this Platonic sense.
Aristotelians, however, have been less charitable in allowing the importance of both kinds of problems about universals. They assume that universals themselves must be like the instances of them in particulars, and then say the Platonic account ascribing independent existence to them is forced to believe in ghostly, wraithlike, disembodied essences. In discussing Platonism Hartshorne himself says, "I do not believe that a determinate color is something haunting reality from all eternity, as it were, begging for instantiation (p. 59). In light of what the Aristotelians are trying to explain, universals can be treated as patterns derived from past actualities. But thc function of universals to explain the Platonist’s problem of formal possibility precludes their being conceived as proceeding from actuality; they are necessarily the antecedent condition of actuality. The Platonic universal for some determinate color is the value that would be actualized if certain refracted light waves and certain conditions of perception are patterned a certain way; in no sense does the universal beg for instantiation, although the concrete world might be better if the color were instantiated.
And so whereas I have no important complaints to make about the positive things Hartshorne says about universals, since he is giving a good account of the Aristotelian problem, his negative points are ill-taken. It is a great mistake to reject all Platonic theories of universals, such as Whitehead’s regarding eternal objects (not that Whitehead’s particular account is necessarily satisfactory). This mistake has serious ramifications for Hartshorne’s view.
Return to his claim that the abstract is contained in the concrete exhaustively, that is, that the union of the abstract and the concrete is simply the concrete. With respect to how universals are ingredient in the world, this claim presents no problem. Universals are structures in the past abstracted as potentialities for actualization in the present, and they have no reality in the world except as potentialities; the concrete realization of them contains them. But with respect to the formal possibility of those universal structures, Hartshorne’s theory gives no account. That they are actually possible is not the issue, since they were actualized in the past. From the Platonist’s side, the interesting question is why certain forms of togetherness are coherent and others not, why certain forms have great harmony and others little or none. Unless this kind of question is addressed, the ontological structure of the world is taken for granted, not made intelligible. Although the question of how this or that form gets ingredient in the world is interesting, the more interesting question is what structure is, how it unifies multiplicity, how it stands related to chaos.
Pushed far enough -- and Hartshorne would surely push it that far -- the claim that structure itself needs an explanation might be thought self-contradictory. First principles are structures, and what could lie behind a first principle? But then, as Peirce said, the only thing that does not need an explanation is pure chaos; order is most of all in need of explanation, and the explanation of a state of affairs in terms of first principles is not as penetrating as the explanation of the first principles themselves. Whereas Hartshorne cites Peirce’s categories as illustrations of eternal metaphysical principles (in contrast to emerging ones), Peirce himself thought his categories of Firstness, Secondness and Thirdness evolved, evolution being the only way to explain the origin of order from chaos (7: pars 12-13). Whitehead in his turn, as Lewis Ford has pointed out, claimed that anything complex needs an explanation in a decision somewhere, and even the metaphysical structures of the world are the result of the divine primordial act giving order to the otherwise chaotic eternal objects (cf. 2). Admitting that difficulties can be raised with both Peirce’s and Whitehead’s accounts, some account of the formal possibility of potentialities is necessary.