Substantialism According to the substantialist, 'Substance and properties are basic, indeed the basic ontological categories.' (Heil 2012, pp. 3-4). Indeed, they may be thought of as complementary categories, so substances are the bearers of properties and properties are the way that substances are (ibid.). If you add the requirement that whatever ultimately bears properties must be metaphysically simple (ibid., p. 20), you must conclude that substances are metaphysical simples. Substances, on this view, are the metaphysical 'fundamental building blocks' (ibid. p. 41). If you then argue that whatever one takes to be metaphysically fundamental should align with that which we take to be physically fundamental, you will further conclude that the fundamental building blocks of physics-whether they are taken to be particles, or fields, or superstrings or whatever-must be substances (ibid., p. 5). Thus, on this view the electron, for example, is a substance that possesses certain properties, such as (rest) mass, charge and spin. A particular (rest) mass, charge and spin is the way the electron, as a substance, is. What this yields is a 'bottom-up' account, according to which we start, ontologically, with these fundamental simples as substances and work our way up through the various 'levels' of reality, from the fundamental to the 'everyday'. So, if we further conceive of properties as powers, or dispositions, the fundamental substances come to be seen as the 'seats' of such powers-an electron, for example, is the seat of an assortment of causal powers as expressed through the above properties (one might hesitate at regarding spin as causal but the recent development of spintronics could be deployed to assuage such doubts). Working our way up, we can then appeal to suitable accounts of composition or emergence or some such, to arrive at the entities that we take to populate the 'everyday' level. To many this is an appealing picture but Cumpa raises the following criticism (2014) based on a proposed criterion for fundamental categories that runs as follows: For every x, x is the fundamental category of the world if and only if x has explanatory power to account for the relation between the ordinary world and the physical universe. (Cumpa 2014: p. 320) This requires that any candidate for fundamentality must be 'cross-sectional' in the sense of crossing or bridging the two levels-that of the 'ordinary world' and that of the 'physical universe'. Unfortunately, Cumpa argues, the above substantialist account fails to meet this criterion, essentially because it fails to be cross-sectional. Thus, consider this table at which I am sitting: we might think that the solidity of the table is a property of it. But according to the above account, only fundamental simples can be considered to be substances and only these truly possess properties. The solidity of the table is not a property per se, it is merely a consequence of the arrangement of fundamental substances; that is, '… what you get when you arrange these substances in thi...
