COMPOSITE. - A composite is that reality in which parts can be distinguished. It can be an aggregate of more ontologically distinct and independent realities (accidental composite) or else an entity that is ontologically one (metaphysical composite). Understood in this latter sense, the composite can consist of essential parts (e.g., soul and body in the human composite) 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., corporeality and sensibility in the human composite).
The concept of composite and of simple underlies Kant’s second antinomy, which arose from the difficulties that the pre-critical Kant had seen in the concept of the continuous and deemed insoluble (v. CONTINUO). In the thesis, which represents the rationalistic theory (Leibniz), Kant affirmed: “Every composite substance in the world consists of simple parts and nothing composite exists anywhere except the simple and what is composed of it” (Critique of Pure Reason, Italian trans., Bari 1945, p. 354); and in the antithesis, which represents the empiricist theory (Hume): “No composite thing consists of simple parts, and nothing simple exists anywhere in the world” (ibid., p. 355). The thesis is erroneous, because, as is evident from the demonstration Kant gave of it, it is based on the false presupposition that the composite is always an aggregate of distinct entities. The antithesis is true if applied to extended composites, which cannot consist of simple entities; yet there also exist composites that are not extended. Moreover, it is false that “nothing simple exists anywhere in the world.”