Individuation, Principle of

INDIVIDUATION, PRINCIPLE OF. - The beings existing in the world, although presenting an essential commonality in their specific nature, are singular and individual: the principle of i. is that from which the individual determination of the specific nature or essence radically derives.

The search for the principle of i. has been a much-discussed problem in philosophy, especially medieval philosophy. It «involves the essential question of philosophy, and is not a simple theme of intellectual exercises, as the problems for which the medieval philosophers were passionate are usually considered» (G. Gentile, Teoria generale dello spirito, 4th ed., Florence 1924, p. 57). The problem, however, has lost much of its importance in modern philosophy; Spinoza still deals with it, framing it within his pantheistic conception of reality, according to which the individual is nothing but a mode of the one divine substance. Leibniz in his youthful Disputatio metaphysica de principio individui (1663) resolves the problem in the nominalistic sense by simply affirming that each thing individuates itself by itself (sua tota entitate individuatur). An allusion to the problem is still found in the pre-critical Kant (Principiorum primorum cognitionis metaphysicae nova dilucidatio [1755]). With the rise of idealistic immanentism the problem of the principle of i. loses the meaning it had in the realistic conception of traditional philosophy, inasmuch as in idealism the plurality of individuals is absorbed into the unity of the transcendental I, although the attempt to explain the multiplicity of the empirical in dependence on space and time still remains. It was precisely in space and time that Schopenhauer had already explicitly placed the principle of i. «for by means of time and space what is one and the same in being and in concept appears instead as different, as a plurality juxtaposed and successive» (Die Welt als Wille u. Vorstellung, I. II, § 23; Ital. trans. by P. Savi Lopez and G. De Lorenzo, I, Bari 1928, p. 143 ff.). In existentialism (v.) the problem of the principle of i. is considered rather from a psychological point of view, and its solution is indicated in the situation (relatives, homeland, epoch, etc.) through which each one is inserted into reality and from which he receives his own individuation. Philosophically, however, the ontological aspect of the problem is more important, obscure and difficult so that Bossuet almost despaired of being able to resolve it (La logique, ch. 23).

In order better to evaluate the different solutions, it is useful to distinguish the various ways in which the principle of i. can be understood. First of all it can serve as a simple manifestative principle of i.: as such it is constituted by that complex of qualities by which the various individuals are empirically distinguished; for example, in the case of man: name, surname, paternity, place and date of birth, more or less deep somatic characteristics such as height, features, color (of eyes, of hair), the timbre of the voice, the fingerprint. The complex of these determinations is generally sufficient to distinguish two living beings of the same species (though not always, as, for example, sometimes in the case of two twins). Not equally easy is determining the distinctive characteristic notes of individuality in inorganic beings, for example, in two molecules of water. And yet these too are individually distinct, and therefore presuppose a constitutive principle of their individuality.

In the search for the constitutive principle of i., the efficient cause has sometimes been indicated, from which every effect receives its singular reality and therefore its individuality. But it must be observed that the efficient cause, extrinsic to the effect, is only the extrinsic principle of i., and the problem concerning the intrinsic principle of i. still remains unsolved, since every being must have in itself (even if received from the cause) the reason for its own individuality. Nor can this intrinsic principle of i. be understood as the complete essence of the individual thing (F. Suárez, Disp. Met., d. 5, s. 6) because it is precisely of that individuality that the principle is being sought; nor as something really distinct from it (the haecceitas of Scotus: In I Sent., 2, d. 3, q. 6), because every thing is essentially singular or individual and therefore the intrinsic principle of i. must be found in its very essence.

Aristotelian-Thomistic metaphysics (Aristotle, Met., XI, 8; St. Thomas, De ente et essentia, ch. 2) indicates in matter the intrinsic constitutive principle of the i. of bodies. Certainly spiritual substances too are individuals, but for them the problem does not exist, because, according to the Aristotelian-Thomistic principles of the limitation and multiplication of act by means of potency (v. ACT AND POTENCY), spiritual essences, not received in a potency, cannot be multiplied within the same species, but are individuals through themselves; every individual is therefore a species, and individuation coincides with specification. This holds all the more for God, whose essence, identifying itself with the pure act of being, is absolutely unmodifiable and therefore through itself individual and singular. The problem is then restricted to material substances (and to accidents), which admit a multiplicity of individuals within the same species. Such multiplicity is possible, for St. Thomas, inasmuch as the act, that is, the specific perfection, is received in a potency or subject, that is, in matter (the accidental act in the substance), and is multiplied and individuated according to the multiplication and individuation of matter. While therefore specification comes from the act, that is, from the form (man is such by the soul), individuation comes from matter (he is «this» man by matter).

Matter, however, is not the principle of i. as prime matter or pure potentiality, but as endowed with quantity; matter in fact without quantity has no extension and therefore has no parts, is neither this nor that, that is, is not individual and cannot therefore individuate the form or act. Instead by virtue of quantity matter is extended and consequently has parts that are distinguished from one another by the different position they have in space (ex situ), are «this» or «that», that is, individual, and can therefore individuate the form. Hence this material substance is «this individual» because it has this essence, composed of this matter and this form; and the form is «this» because received in this matter which is «this» because it is this determinate part in the totality of corporeal matter; «signate matter» is therefore the intrinsic constitutive principle of i. of corporeal substances.

Regarding "materia signata," a question arises among the Scholastics as to whether the "signatio" or individualization of matter is due to the order that it bears to quantity or to quantity itself as actually informing matter. The problem derives from the fact that matter cannot be informed by quantity unless it has its own act or substantial form, prior to every accident; on the other hand, matter cannot individuate form unless it is itself individual; whence some Scholastics conclude, with Cajetan (Comment. in De ente et essentia s. Th. Aq., ch. 2), that since matter must be individual before receiving quantity in order to be able to individuate form itself, the individuation of matter occurs not through quantity as actually informing matter, but through the "order" to quantity that is in matter prior to quantity itself. But others rightly observe, with the Ferrarese (Comment. in Sum. c. Gent. I, 21) and according to the opinion of Capreolus (Defens. theol. d. Th. Aq., t. III, ed. C. Paban & Th. Pègues, Tours 1902, p. 200 ff.), that the priority of substantial form with respect to accidental form or quantity is a priority of nature, not of time, so that in the same instant there are matter, form and quantity, which together concur to constitute the new entity: form specifying, quantity marking matter, and matter limiting and individuating form.

The indicated solution is not made difficult by the soul of man, which, being immortal, subsists after death as individual and singular, even though it is not united to matter. For the human soul, insofar as it is spiritual, has being independent of the body and therefore, although created in the body and individuated by it, just as it preserves its own subsistent being, so it preserves its own individuation, remaining always such a form ready to reconstitute that same one.

the individual, when (philosophy ignores it, but faith teaches it) he will be reunited with the body in the final Resurrection.

Paolo Dezza