Abstract: The main purpose of this book is to give an analysis of ordinary material objects, those material objects to which we take ourselves to be committed in ordinary, scientifically informed discourse. Particular focus is placed on the question of how the parts of such objects are related to the wholes which they compose. Many philosophers today find themselves in the grip of an exceedingly deflationary conception of what it means to be an object, according to which any plurality of objects, no matter how disparate or gerry-mandered, itself composes an object, even if the objects in question fail to exhibit interesting similarities, internal unity, cohesion, or causal interaction amongst each other. This commitment to initially counterintuitive objects follows from the belief that no principled set of criteria is available by means of which to distinguish intuitively gerry-mandered objects from common-sensical ones. The project of this book is to persuade the reader that systematic principles by means of which composition can be restricted can be found, and hence, that we need not embrace this deflationary approach to the question of what it means to be an object. To this end, a more full-blooded neo-Aristotelian account of parthood and composition is developed according to which objects are structured wholes: it is integral to the existence and identity of an object, on this conception, that its parts exhibit a certain manner of arrangement. This structure-based conception of parthood and composition is explored in detail, along with some of its historical precursors as well as some of its contemporary competitors.

Keywords: part, whole, object, composition, structure, mereology, unity, kind, form, matter