On atomic composition as identity

Abstract

In this paper I address two important objections to the theory called ‘(Strong) Composition as Identity’ (‘CAI’): the ‘wall-bricks-and-atoms problem’ (‘WaBrA problem’), and the claim that CAI entails mereological nihilism. I aim to argue that the best version of CAI capable of addressing both problems is the theory I will call ‘Atomic Composition as Identity’ (‘ACAI’) which consists in taking the plural quantifier to range only over proper pluralities of mereological atoms and every non-atomic entity to be identical to the (proper) plurality of atoms it fuses. I will proceed in three main steps. First, I will defend Sider’s (in: Baxter D, Cotnoir A (eds) Composition as identity. Oxford University Press, Oxford, pp 211–221, 2014) idea of weakening the comprehension principle for pluralities and I will show that (pace Calosi in Philos Q 66(263):219–235, 2016a) it can ward off both the WaBrA problem and the threat of mereological nihilism. Second, I will argue that CAI-theorists should uphold an ‘atomic comprehension principle’ which, jointly with CAI, entails that there are only proper pluralities of mereological atoms. Finally, I will present a novel reading of the ‘one of’ relation that not only avoids the problems presented by Yi (J Philos 95:163–190, 1999a, in: Baxter D, Cotnoir A (eds) Composition as identity. Oxford University Press, Oxford, pp 169–191, 2014) and Calosi (Log Log Philos 25(3):429–443, 2016b, Am Philos Q 55(3):281–292, 2018) but can also help ACAI-theorists to make sense of the idea that a composite entity is both one and many.