Gilbert’s theory of individuality is clearly distinct from a long tradition, in which Boethius, Eriugena, Anselm of Canterbury, William of Champeaux, Thierry of Chartes, but not Abelard concur (called STI: ‘‘Standard Individuation Theory’’ by Gracia 1988; cfr. Maioli 1974:LI-LII). According to STI it is the accidents alone, which make individuals of the same species being numerically one and the same unique ‘‘communal quality’’ (qualitas communicata) is found complete (tota) in every individual of the same species: Cato and Cicero are one identical entity - idem - in that, belonging to the same species Man, they share the same humanitas; while they are numerically different from one another - plures - only because of the diversity of their accidents. For Gilbert, rather, the numerical diversity of subsistents is due, not only to the accidents, but to all of the forms, accidental and substantial, which come together to constitute them: there exist as many diverse humanitates as men. The differences in the accidents do not provide the basis for the numerical diversity of subsistents, but merely indicate it. Singularity, that is, being numerically one, is an intrinsic characteristic of every entity, whether it is a compound or a form, and is presented in Gilbert’s ontology as a primary, non-deducible given. Moreover, unlike his predecessors, Gilbert in consequence considers the concepts of singularity and individuality to be different. The set of individuals is a subset of the set of singulars: everything that exists is singular, but not all that exists is both singular and individual. Only subsistents and complete forms of subsistents are singular and individual. The subsistent (e. g., Socrates) and the tota forma of each subsistent (socrateitas), are singulars and individuals, that is to say not dividuals, because they are not similar to any other entity either in act or just in potency (Comm. Contra Euticen, p. 272, l. 45-274, l. 93). By contrast, a form is dividual which, whether simple (rationality) or compound (humanity), turns out to be, judging from its effects, similar to other forms, if not in act then at least in potency. On the basis of this similarity these forms are said to be conformes to each other (the humanity of Socrates and that of Plato are similar in potential and in act; the being-the-sun ofthe sun is similar not in act but at least in potential to the being-the-sun of another sun, which does not exist, did not exist, and will never exist, but could exist: Comm. Contra Euticen, p. 273, ll. 68-74). Finally, those entities which, though dissimilar from every other entity, are nonetheless part of another individual are not themselves individuals, for they share their own formal characteristics with the compound whole. The soul is not therefore an individual since it shares its formal characteristics with man, of which, with the body, it is a part. Since it is not an individual, the soul is not a person either, according to the Boethian definition of the person as ‘‘naturae rationabilis individua substantia’’ (Comm. Contra Euticen, p. 271, l. 14-274, l. 95). It should be observed, however, that Gilbert gives this definition with an important clarification and modification: the clarification is that no person can be part of a person; the modification is that for him the characterization of person as rational is purely conventional, due to the usage of philosophers. Strictly speaking, even plants and animals are persons: for they are individual substances, which are each dissimilar to every other entity and are not parts of any further compound entity (Comm. De trinitate, p. 146, ll. 14-23). In this sense, it would seem that Gilbert does not make a real distinction between person and individual (Elswijk 1966:192; Maioli 1979:339; but the interpreters disagree over Gilbert’s characterization of the concept of person; cf. Nielsen 1982:62-64; Marenbon 1988:346; Jacobi 1996:17-19).
It has been observed (Knuuttila 1987, 1993:75-82; recalling Nielsen 1982:62-64, 180, 184) that, since he considers that the properties the subsistent does not ever effectively possess but could possess according to the potency of its own nature are parts of the total form, he is proposing a ‘‘modal’’ theory of individuality. This conception presupposes the idea of possible worlds and possible alternative histories of the world and the conviction, not really argued for, of the stability of individual identity across various possible worlds and various possible histories (Knuuttila 1993:81). But Gilbert’s modal definition of individuality seems to have the undesirable consequence of dissolving the very individuality he wishes to define: indeed, if taken literally, Gilbert’s definition seems to imply that the complete form of every individual of a species includes all the possible determinations of every other individual of that species. It follows that the complete forms of individuals of the same species would all be similar to each other, and so dividuae (Marenbon 1998:171). Gilbert’s appeal to a modal definition of individuality, and thus to the idea of different worlds and histories, can be traced to a keenly felt need to conserve as far as possible God’s omnipotence, which is not subject to any necessity whatsoever except in that of certain basic rules of logic set out in the theory of topical argumentation. Of which parts the various subsistents are composed, and of which general, differential, and accidental subsistences the complete forms of the subsistents of different species are composed also depends on God’s omnipotence and will and is not necessary in an absolute sense. Such compositions are governed by the merely relative necessity of the habitual course of things (consuetude rerum) and of the usual condition of natural beings (usus nascentium, qui vocatur natura: Comm. De trinitate, p. 164, ll. 34-41; Comm. Contra Euticen, p. 304, ll. 83-91).
World History
