On the Constitution of Solid Objects Out of Atoms

1. IntroductionA number of philosophers have questioned whether objects that are undoubtedly ontological units could combine to form a whole that was also an ontological unit of the same standing. Leibniz, Bertrand Russell, Peter van Inwagen, and Trenton Merricks are well-known examples of such philosophers.1 In this paper I consider this issue for solid objects by focussing on their causal properties. I begin by considering the various different kinds of property that a whole object could possess and the ways in which those properties could be related to the properties of the atoms. In order to assess which properties of the whole are ontologically significant, a distinction is made between algorithmic elimination and causal or explanatory elimination, where a term has been eliminated algorithmically if it can be dispensed with in calculations. For example, it is claimed by instrumentalists that "theoretical terms" are mere convenient calculating devices (parts of algorithms) that could be eliminated and play no role in explanations. But here it is argued that algorithmic elimination does not entail causal elimination. Finally, it is argued that though a solid object and its atoms both have properties, when it comes to the causal action of a solid object, in many significant interactions (though not all) it is the whole object and its properties that act.2In order to form a solid object, certain atoms must be stuck together so that each atom is stuck to each of some neighbouring atoms by the dyadic, solid-making "stuck to" relation and those atoms are stuck to further atoms by the same relation, and finally all the atoms that are constituents of the solid are stuck together by the more general, transitive "stuck to" relation and are stuck to no other atoms. A more detailed account of solid objects is given in section 6 and fh. 26.By 'atom' is meant the fundamental constituents of matter, whatever you take them to be. They could be (1) atoms properly so-called denned by their atomic numbers, molecules, and ions, (2) the first constituents of atoms, namely electrons, protons, and neutrons, (3) the fundamental particles of the standard model, or (4) just plain old, hypothetical, philosophical atoms as hypothesized by people like Democritus and Trenton Merricks. Interatomic forces are then the forces between atoms whatever you take them to be. I believe that there are reasons for thinking that atoms properly so-called, molecules, and ions are real units and therefore respectable "atoms."2. Properties of Wholes and Properties of PartsIn order to discuss solid objects, it is necessary to consider in general the various ways in which it is possible for properties of atoms to be related to properties of a whole object that is constituted out of those atoms. The usual expectation is that the atoms' possessing certain properties, being arranged spatially in a certain way, and with certain forces connecting them, bring about the instantiation of a property of the whole as a matter of natural law or perhaps as a matter of metaphysical necessity. In other words, the properties of the atoms, their spatial arrangement, and the forces between them determine the properties of the whole. There are two ways in which this could happen, first, where the properties of the atoms, their arrangement, and the forces between them determine that a specific property (a determinate) of a certain kind (a determinable) be instantiated by the whole. Secondly, where the properties of the atoms, their arrangement, and the forces between them determine that some property (a determinate) of a certain kind (a determinable) within a certain range be instantiated by the whole, but do not determine which one.3 In such cases, the properties of the atoms, their arrangement, and the forces between them are necessary conditions for the instantiation of a property of a certain kind of the whole, but even jointly they do not constitute sufficient conditions for the instantiation of any specific property ofthat kind. …