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).

Some philosophers say that a whole is “nothing over and above” its parts. Most also take general extensilonal mereology to be treating wholes as “nothing over and above” their parts. It is not always clear, however, what exactly is meant by the phrase “nothing over and above.” Nor is it obvious why the phrase is associated with mereology, and what purpose it serves there. In the words of Peter Van Inwagen : “This slippery phrase has had a lot of employment (...) in philosophy, but what it means is never explained by its employers.” This paper sheds light on the various senses in which one might hold that a whole is “nothing over and above” its parts, and on how these senses are related both to each other and to mereology. (shrink)

Mereological universalists, according to whom every plurality of entities has a fusion, usually claim that most quantifications are restricted to ordinary entities. However, there is no evidence that our usual quantifications over ordinary objects are restricted. In this article I explore an alternative way of reconciling Mereological Universalism with our usual quantifications. I resort to a modest form of ontological expansionism and to the so-called interpretational modalities. Quantifications over ordinary objects are the initial stages of the expansion. From these initial (...) stages, expansions can proceed upwards (fusions of entities in the domain of quantification are added), downwards (parts of entities in the domain are added), and sidewards (entities which are mereologically disjoint from the entities in the domain are added). These expansions are driven by a variety of epistemic and pragmatic reasons and raise different kinds of problems. At each stage, a modalized version of Mereological Universalism is true. By contrast, only at some especially rich stages, standard, non-modalized Mereological Universalism is true as well. Among these especially rich stages, there is a final, metaphysically pre-eminent stage of mereological plenitude. In the last part of the article I discuss some problems and limitations of expansionism. (shrink)

In this paper, I criticize Structured Propositionalism, the most widely held theory of the nature of propositions according to which they are structured entities with constituents. I argue that the proponents of Structured Propositionalism have paid insufficient attention to the metaphysical presuppositions of the view – most egregiously, to the notion of propositional constituency. This is somewhat ironic, since the friends of structured propositions tend to argue as if the appeal to constituency gives their view a dialectical advantage. I criticize (...) four different approaches to providing a metaphysics of propositional constituency: set-theoretic, mereological, hylomorphic, and structure-making. Finally, I consider the option of taking constituency in a deflationary, metaphysically ‘lightweight’ sense. I argue that, though invoking constituency in a lightweight sense may be useful for avoiding the ontological problems that plague the ‘heavyweight’ conception, it no longer proffers a dialectical advantage to Structured Propositionalism. (shrink)

Identifying plausible truthmakers for negative truths has been a serious and perennial problem for truthmaker theory. I argue here that negative truths are indeed made true but not in the way that positive truths are. I rely on a distinction between “existence-independence” and “variation-independence” drawn by Hoffman and Horvath to characterize the unique form of dependence negative truths exhibit on reality. The notion of variation-independence is then used to motivate a principle of truthmaking for contingent negative truths.

I first explore the notion of the world's being such that everything in it is a proper part. I then explore the notion of the world's being such that everything in it both is and has a proper part. Given two well recognized assumptions, I argue that both notions represent genuine metaphysical possibilities. Finally I consider, but dismiss, some possible objections.

In this thesis I argue against unrestricted mereological hybridism, the view that there are absolutely no constraints on wholes having parts from many different logical or ontological categories, an exemplar of which I take to be ‘mixed fusions’. These are composite entities which have parts from at least two different categories – the membered (as in classes) and the non-membered (as in individuals). As a result, mixed fusions can also be understood to represent a variety of cross-category summation such as (...) the abstract with the concrete, the physical with the non-physical, and the possible with the impossible, just to name a few. -/- Proposed by David Lewis (1991) alongside his defence of classical mereology (the major theory of parthood which permits such transcategorial composites through its principle of unrestricted composition) it is my contention that mixed fusions are an under-examined consequence of indiscriminate mereological fusion which harbour a multitude of complications. In my attempt to discern their substantive character, throughout this thesis I make a case study of mixed fusions and uncover several problematic consequences which I think follow from their most plausible assessment. -/- These include: (1) that mixed fusions’ probable membership relations may lead to dubious foundational loops in the mereological Universe, or (2) otherwise that mixed fusions oblige an implausible ontological priority of the mereological Universe as a whole; (3) that mixed fusions contradict the reductive account of set theory they are proposed within, by plausibly being seen to have the same members as their class parts, and (4) that mixed fusions therefore confound a mereological thesis of Composition as Identity, which some (including Lewis) use to support classical mereology – a consequence which is potentially self-defeating; (5) that mixed fusions as sums of abstract and concrete entities both subvert Lewis’s (1986) system of modal realism, while (6) also undermining less expansive theories of possible worlds; and finally, (7) that even where some of the foregoing is resisted, it remains implausible that mixed fusions are ontologically innocent, because their supposed distinction from their parts in this case ensures that they need to be counted as additional entities in one’s ontology. -/- To be clear, I do not advance a theory of mereological hybrid nihilism in the sense of denying all cases of transcategorial composition. (I only cover a few select instances of mereological hybridism via mixed fusions after all.) Rather, I deny that mereological hybridism is plausible in full generality, by demonstrating that any cases of it are at least limited by the constraints that I identify. This in turn vindicates a call for a restriction on parthood theories and composition principles which allow certain types of categorially mixed entities – including restricting classical mereology with its principle of unrestricted composition. -/- Although theories of parthood like the standard classical mereology are not ordinarily developed for the sake of mereological hybrids like mixed fusions, these and other transcategorial composites are still among the logical consequences of such parthood systems operating with sufficient generality. The significance of my thesis, then, comes from showcasing how some of these kinds of entities do not conform to the systems in which they are included as required, and hence I argue for the rejection of unrestricted mereological hybridism as well as any mereological principles which support it. (shrink)

Composition as Identity is the view that an object is identical to its parts taken collectively. I elaborate and defend a theory based on this idea: composition is a kind of identity. Since this claim is best presented within a plural logic, I develop a formal system of plural logic. The principles of this system differ from the standard views on plural logic because one of my central claims is that identity is a relation which comes in a variety of (...) forms and only one of them obeys substitution unrestrictedly. I justify this departure from orthodoxy by showing some problems which result from attempts to avoid inconsistencies within plural logic by means of postulating other non-singular terms besides plural terms. Thereby, some of the main criticisms raised against Composition as Identity can be addressed. Further, I argue that the way objects are arranged is relevant with respect to the question which object they compose, i.e. to which object they are identical to. This helps to meet a second group of arguments against Composition as Identity. These arguments aim to show that identifying composite objects on the basis of the identity of their parts entails, contrary to our common sense view, that rearranging the parts of a composite object does not leave us with a different object. Moreover, it allows us to carve out the intensional aspects of Composition as Identity and to defend mereological universalism, the claim that any objects compose some object. Much of the pressure put on the latter view can be avoided by distinguishing the question whether some objects compose an object from the question what object they compose. Eventually, I conclude that Composition as Identity is a coherent and plausible position, as long as we take identity to be a more complex relation than commonly assumed. (shrink)

An overview of contemporary part-whole theories, with reference to both their axiomatic developments and their philosophical underpinnings.

This entry focuses on two of the more historically important monisms: existence monism and priority monism . Existence monism targets concrete objects and counts by tokens. This is the doctrine that exactly one concrete object exists. Priority monism also targets concrete objects, but counts by basic tokens. This is the doctrine that exactly one concrete object is basic, which will turn out to be the classical doctrine that the whole is prior to its parts.

Abstract: Friends of plural logic—like Oliver & Smiley (2001), Rayo (2002), Yi (2005), and McKay (2006)—have argued that a semantics of plurals based on mereological sums would be too weak, and they have adduced several examples in favor of their claim. However, they have not considered various possible counter-arguments. So how convincing are their own arguments? We show that several of them are easily answered, while some others are more problematic. Overall, the case against mereological singularism—the idea that mereological sums (...) can serve as the semantic values of plurals—turns out to be much less strong than what it is usually presented to be. (shrink)

The branching time analysis grounds the possibilities entailed by temporal indeterminism in a branching temporal structure. I construct a spatial analog of the branching time analysis – the branching space analysis – according to which the possibilities entailed by spatial indeterminism are grounded in branching spatial structure. The construction proceeds in such a way as to show the analogies between the branching space and branching time analyses. I argue that the two views are a package. In particular: the theoretical virtues (...) of the one are theoretical virtues of the other and so if one ought to be accepted, then the other should also be accepted. And: if one ought to be denied, then the other ought to be denied as well. Thus, the branching space analysis functions either as a counterexample to the reductive strategy embodied in the branching time analysis or as a reasonable extension of it – as a lesson learned from it. (shrink)

A critical survey of the fundamental philosophical issues in the logic and formal ontology of space, with special emphasis on the interplay between mereology (the theory of parthood relations), topology (broadly understood as a theory of qualitative spatial relations such as continuity and contiguity), and the theory of spatial location proper.