Compound

COMPOUND. - A compound is that reality in which parts can be distinguished. It can be an aggregate of several ontologically distinct and independent realities (accidental compound) or instead an ontologically one entity (metaphysical compound). Understood in this latter sense, the compound may consist of essential parts (e.g., soul and body in the human compound) or integral parts (e.g., the organs that make up the human body). Scholastic terminology further distinguishes essential parts into physical (e.g., matter and form as constitutive principles of the body) and metaphysical (e.g., corporeity and sensibility in the human compound).

The second Kantian antinomy is based on the concept of compound and of simple, arising from the difficulties that the pre-critical Kant had seen in the concept of the continuum, and believed insoluble (v. CONTINUO). In the thesis, which represents the rationalist theory (Leibniz), Kant affirmed: "every compound substance in the world consists of simple parts and there exists nowhere anything but the simple and what is composed of it" (Critique of Pure Reason, Ital. trans., Bari 1945, p. 354); and in the antithesis, which represents the empiricist theory (Hume): "no compound thing consists of simple parts, and in the world there exists nowhere anything simple" (ibid., p. 355). The thesis is erroneous, because, as can be seen from the demonstration Kant gave of it, it is founded on the false presupposition that the compound is always an aggregate of distinct entities. The antithesis is true, if it is referred to the extended compound, which cannot consist of simple entities; but there also exist compound entities that are not extended. It is false furthermore that "in the world there exists nowhere anything simple."

In experimental science, a compound is that body which, when suitably treated, splits into specifically different bodies, differing, by this character, from the element, which does not admit such further specification. Modern chemistry distinguishes about 90 elements, catalogued according to Mendeleev's table. Atomic and nuclear physics has further discovered that every body, including the elements, is formed of subatomic corpuscles: proton, neutron, electron, positron and perhaps some other. The theory of quantum mechanics teaches that these particles are to be considered as corpuscle-waves. Such scientific discoveries today make more vivid the problem of whether the compound body must be conceived as an aggregate of elements (corpuscles) or rather as a single substance. Theoretically, if the compound body is an aggregate of elements, these are found in it as distinct and individual; if instead the compound is a single substance, the elements are not actually distinct in it, since a substance, insofar as it is one, cannot result from an aggregate of substances. If the compound is ontologically one, the elements are in it potentially or, as it is said, virtually, insofar as the compound, although being one, by reason of its origin from several elements, is constituted in such a way as to have, in its different parts, properties similar to those of the component elements, and to permit, in disintegrating, the reappearance of the elements that entered into forming it, and in the same proportion (Proust's law).

In order to decide how, in the inorganic world, the elements are in the compound, experience must be consulted. Modern physics interpreted experiments by orienting itself toward the schemas of mechanical metaphysics (it suffices to recall Bohr's theory, according to which the atom is a mechanical system of electrons rotating around the nucleus) and thought of an actual existence of the elements in the compound, considering all bodies, except the primordial particles, as more or less stable aggregates of corpuscles, bound together by different forces. But the most recent physics (quantum mechanics) interprets experiments differently, rejects mechanical schemas and tends rather to consider atoms and other complex bodies as unitary systems, in which the components have lost their individuality. Present-day physics is therefore inclined to consider compound bodies, at least some of them (atom, molecule, etc.), as substantial unities, in which the elements exist virtually.

Roberto Masi