The Theory of Matter

“The theory of matter” can mean many things, ranging from the most abstract metaphysical issues about persistence and change, identity and individuation, down to detailed empirical issues about the actual constitution of bodies. The metaphysician might enquire whether more than one form can coexist in the same portion of matter. The chemist might ask whether the so-called elements fire, air, water, and earth are indeed the ultimate constituents of all material things, and, if so, how they are present in compounds. At first sight, they are addressing very different questions, one informed by textual scholarship and hard thought, the other by hands-on experience in the laboratory. But the answer to the metaphysician’s question has implications for the chemist and vice versa. Similarly, the metaphysician might investigate the actuality or otherwise of the parts of a body before division; the natural philosopher might seek an account of some of the properties of bodies in terms of the arrangement of their parts. Here the very intelligibility of a programme in natural philosophy depends on a particular answer to a deep and difficult question of metaphysics. Arguments in matter theory can clearly run both ways. We might start with first principles and use a set of accepted principles to set constraints and impose guidelines on empirical research. Or we could argue back from successful empirical work to the picture of nature that they presuppose. Philosophers of a “rationalist” persuasion such as Descartes and Leibniz will tend to favour the former approach; philosophers of an “empiricist” persuasion such as Boyle and Locke will favour the latter. ¹