In a recent article in this journal, Achille Varzi (2009) argues that mereological universalism (U) entails mereological extensionalism (E). The thesis that U entails E (call it ‘T’) has important implications. For example, as is well known, T plays a crucial role in Peter van Inwagen’s argument against universalism (1990: 74–79). In what follows, I show that Varzi’s arguments for T rely on a tendentious assumption about parthood.

Partial grounding is often thought to be formally analogous to proper parthood in certain ways. Both relations are typically understood to be asymmetric and transitive, and as such, are thought to be strict partial orders. But how far does this analogy extend? Proper parthood is often said to obey the weak supplementation principle. There is reason to wonder whether partial grounding, or, more precisely, proper partial grounding, obeys a ground-theoretic version of this principle. In what follows, I argue that it (...) does not. The cases that cause problems for the supplementation principle for grounding also serve as counterexamples to another principle, minimality, defended by Paul Audi. (shrink)

Does a commitment to mereological universalism automatically bring along a commitment to the controversial doctrine of mereological extensionalism—the view that objects with the same proper parts are identical? A recent argument suggests the answer is ‘yes’. This paper attempts a systematic response to the argument, considering nearly every available line of reply. It argues that only one approach—the mutual parts view—can yield a viable mereology where universalism does not entail extensionalism.

The present paper has three closely related aims. We first argue that Agazzi’s scientific realism about Quantum Mechanics is in line with Selleri’s and Tarozzi’s proposal of Quantum Waves. We then go on to formulate rigorously different metaphysical principles such as property compositional determinateness and mereological extensionalism. We argue that, contrary to widespread agreement, realism about Quantum Mechanics actually refutes only the former. Indeed we even formulate a new quantum mechanical argument in favor of extensionalism. We conclude by noting that, (...) given the results of the work, Agazzi’s particular attitude towards Quantum Mechanics is still one of the most promising theoretical perspectives. (shrink)

The paper addresses various questions about the logical and metaphysical relations between notions of parthood, location and persistence. In particular it argues that the conjunction of mereological extensionalism and multilocation, is highly problematic, if not utterly inconsistent. It thus provides an alternate route to reject multilocation, one that does not rely on Barker and Dowe's well known argument, at least for those who endorse extensionality of parthood. It then argues that other major metaphysical theses such as three-dimensionalism turn out to (...) be at odds with extensionalism. (shrink)

David Lewis famously endorsed Unrestricted Composition. His defense of such a controversial principle builds on the alleged innocence of mereology. This innocence defense has come under different attacks in the last decades. In this paper I pursue another line of defense, that stems from some early remarks by van Inwagen. I argue that Unrestricted Composition leads to a better metaphysics. In particular I provide new arguments for the following claims: Unrestricted Composition entails extensionality of composition, functionality of location and four-dimensionalism (...) in the metaphysics of persistence. Its endorsement yields an impressively coherent and powerful metaphysical picture. This picture shows a universe that might not be innocent but it is certainly elegant. (shrink)