Material constitution, as I have construed it, is not a mereological relation: It is not defined in terms of a relation of parts to wholes. However, there are many philosophers who suppose that ordinary material objects must be understood in terms of a single, comprehensive relation of parts to wholes. Philosophers who look to mereology to understand objects often simply eschew an ontological account of ordinary objects in favor of a “conceptual” account, according to which there is nothing ontological that makes a person a person or a painting a painting. Ontologically, there are just little items that compose sums, some of which we choose to call persons and others of which we choose to call paintings.

Since the aim of this book is to provide an ontological basis for the familiar objects that we encounter – including people, artworks, artifacts, and ID objects generally – I do not take constitution to be a mereological relation: A piece of paper is not part (proper or improper) of the dollar bill that it constitutes. Constituted objects are not identical to any sums. Nevertheless, I want to show here that, although constitution itself is not a mereological relation, the Constitution View has a place for mereology. Sums are the ultimate constituters.

My goal in this chapter is not so much to defeat opponents as to show that the Constitution View can give an ontological account of our ordinary talk about parts.