The relationship of part to whole is one of the most fundamental there is; this is the first and only full-length study of this concept. This book shows that mereology, the formal theory of part and whole, is essential to ontology. Peter Simons surveys and criticizes previous theories, especially the standard extensional view, and proposes a more adequate account which encompasses both temporal and modal considerations in detail. 'Parts could easily be the standard book on mereology for the next twenty (...) or thirty years.' Timothy Williamson, Grazer Philosophische Studien. (shrink)

I argue that Universalism (the thesis that mereological composition is unrestricted) entails Extensionalism (the thesis that sameness of composition is sufficient for identity) as long as the parthood relation is transitive and satisfies the Weak Supplementation principle (to the effect that whenever a thing has a proper part, it has another part disjoint from the first).

This paper defends Mereological Universalism(the thesis that, for any set S of disjoint objects, there is an object that the members of S compose. Universalism is unpalatable to many philosophers because it entails that if there are such things as my left tennis shoe, W. V. Quine, and the Taj Mahal, then there is another object that those three things compose. This paper presents and criticizes Peter van Inwagen's argument against Universalism and then presents a new argument in favor of (...) Universalism. It turns out that the most reasonable way to resist the argument for Universalism is to deny the existence of artifacts; thus, if we believe in artifacts, we have no real choice other than to embrace Universalism. (shrink)

There is a tradition according to which Parmenides of Elea endorsed the following set of counterintuitive doctrines: (a) There exists exactly one material thing. (b) What exists does not change. (g) Nothing is generated or destroyed. (d) What exists is undivided. For convenience, I will use the label ‘Eleatic monism’ to refer to the conjunction of a–d.

Mereological Universalism is the thesis that, for any disjoint Xs, the Xs automatically compose something. In his book, Material Beings, Peter van Inwagen provides an argument against Universalism that relies on the following crucial premiss: (F) If Universalism is true, then the Xs cannot ever compose two objects, either simultaneously or successively.1 I have argued elsewhere (Rea 1998) that van Inwagen’s defence of (F) fails because it relies on the false assumption that Universalism is incompatible with the view that, for (...) some Xs, what the Xs compose depends upon how the Xs are arranged. However, Matthew McGrath (1998) has recently provided a new – and in his opinion, better – formulation of van Inwagen’s argument for (F). Furthermore, he claims (contrary to what van Inwagen himself apparently thinks) that four of the ten assumptions listed at the outset of Material Beings are ‘jointly sufficient for the falsity of Universalism’. (1998: 121) Those assumptions, as they appear on page 121 of McGrath 1998, are as follows. (shrink)