AAP 2026 CONFERENCE

Under one conception of philosophy, we are to seek the truth under the guidance of logical reasoning. Nothing is more fundamental to that kind of philosophy than entailment—except perhaps a handful of core concepts like being and nonbeing, sameness and difference. Here, we explore a theory that grounds entailment in the being and nonbeing of properties. In a nutshell: we understand ‘properties’ to be ways for things to be. We assume that there exist ways for things to be. We understand one thing to ‘entail’ another when there is no way to avoid it. We take these occurrences of ‘to be,’ and ‘there exist,’ and ‘there is no way,’ and other such terms, as applied to ‘properties’ and ‘ways,’ with robust ontological seriousness. The same ontological seriousness applies to the kind of necessitation that is intrinsic to the laws of nature. Things obey the laws of nature because there is no way for those things to do anything else. To tease out what that means requires the construction of a detailed theory of properties construed as ways for things to be.
 

Cases of coincidence, the paradigmatic example being the statue and the lump of clay, involve purported property differences that motivate the claim that there are numerically distinct coincident objects. These cases are philosophically important insofar as they put pressure on a range of interconnected questions and intuitions about material objects and their individuation, persistence conditions, location, and mereology.

The standard taxonomy of responses to these cases is relatively coarse-grained: one either accepts numerically distinct coincident objects (pluralism) or rejects them (monism), with a handful of further disagreements among variants. I argue that this picture significantly underdescribes the landscape and that disagreement over these cases involves several dimensions.

I will focus on the distinction between different ways that coincident, or merely apparently coincident, objects might be related to one another, differentiating locative coincidence from mereological coincidence. I then offer and defend methodological conceptual pluralism: a particular view about which concept(s) of coincidence we ought to employ, given the goal of clarifying what these cases consist of. This reveals multiple layers of disagreement: metaphysical, conceptual, and higher-order conceptual. The result is a far more fine-grained set of competing views of what these cases involve. It also shows that some arguments for or against the standard coarse-grained positions, in fact, target only subsets of these more fine-grained views.

Metaphysical foundationalists hold that grounding has an explanatory role and that this role can be fulfilled only if there are fundamental entities. Accordingly, anti-foundationalist views face a charge of explanatory failure: without a fundamental level, certain explanatory demands go unmet. Recently, Cameron (2022) has challenged the assumption that grounding is inherently explanatory. If this argument succeeds, it provides the anti-foundationalist a way to resist the foundationalist’s charge by severing the connection between grounding and explanation.

In this talk, I defend foundationalism against this strategy in two ways. First, I show that Cameron’s objections stem from a conflation of distinct explanatory claims and, at times, from misidentification of the direction of the grounding relation. Once we correct these issues, the link between grounding and explanation is successfully preserved. Second, I show that detaching explanation from grounding carries significant theoretical costs: it weakens grounding’s ability to play its central structuring role in metaphysics and blurs its identity, rendering it indistinguishable from other dependence relations. Finally, I argue that separating grounding from explanation undermines our understanding of the nature of grounding itself and exposes it to skeptical concerns about its intelligibility.

Explanatory appeals to abstract ‘objects’ (numbers, moral values/principles, possible worlds etc…) are ubiquitous in philosophy, science, and everyday reasoning. Cicadas emerge in prime-number cycles because of number-theoretic advantages, lying is wrong because it violates the categorical imperative, Celtic FC would have won yesterday’s match had the referee been unbiased. Many philosophers take such claims’ explanatory usefulness to justify ontological commitment to the abstracta involved. Yet, by definition, abstracta are spatially and causally removed from the concrete world we seek to explain, raising a fundamental question: when, if ever, does explanatory appeal to abstracta genuinely license belief in their existence?

To answer this, I propose a methodological framework which distinguishes merely representative/heuristic explanations from metaphysically substantive ones. Two criteria structure the framework: ‘Basis’, scrutinises the reality of explanans and explanandum (independent of their inclusion in a particular explanation); and ‘Relevance’, assessing whether the explanans stands in an appropriate ontic-explanatory relation to the explanandum.

Applying this framework to case studies in mathematics, morality, and modality, I argue that explanatory appeals to abstracta systematically fail both criteria. Abstraction may be an indispensable representational tool, but abstracta themselves are never adequate explanans for why the concrete world truly is as it is.

In this paper, I address the Special Omission Question (SOQ): under what conditions does a disjunction count as an omission? If omissions are events essentially specified as non-occurrences, then their conditions of occurrence can be formulated as disjunctions of overly varied disjuncts. This suggests that omissions are disjunctive events. For example, one might say that the universe omits to contain events that violate the laws of nature (see Lewis 1986a: 190). I suggest that this kind of case still counts as an omission, and I further discuss some additional difficult cases that have largely been ignored in the literature.
I consider three possible answers to the SOQ: always, never, and sometimes. Rather than decisively rejecting the first two options, I develop the ‘sometimes’ view: some disjunctions count as omissions, while others do not. This view provides a way to distinguish genuine omissions from arbitrary disjunctions. Compared with my theory, I suggest that Silver’s (2018) theory is not adequate to account for omissions.

What is time? We suggest we have failed to answer this question in the way it needs to be answered. We go on to offer an answer: time is the great enabler, it makes causation and change possible. We explain what that means, and demonstrate it by applying it to a range of cases.

In ‘Constructing Moral Equality’ (2022) I argued that we can productively think of the human as a social, rather than a natural, kind; and furthermore, that being constructed as human entails being constructed as a moral equal. In this paper I argue that I was wrong (at least in part). Armed with a more nuanced social metaphysical framework, I explore the possibility that while one of the mechanisms through which the human is constructed confers a formal equality of status on all members of the kind, other mechanisms simultaneously constitute some people as inferior.

It is generally accepted that agency requires materiality, since action must originate somewhere. In group agents, this implies that they are agential material objects rather than hovering, mind-like entities (Hess 2025). I argue that the material existence of group agents can be best explained by a Baker-style constitution relation (2000) between a group and its members, which is strictly non-mereological.
First, I argue against Collins (2023) that her mereological account of group agents cannot successfully explain the relation between a group and its members because it fails to meet the non-transitivity desiderata of group agents. I subsequently show how this critique can be generalized to all mereological proposals (Hawley 2017; Hansson Wahlberg 2014). 
Secondly, I argue that the existing constitution accounts of group agents either fail to identify the correct material object from which the action of a group originates (Epstein 2015; Hindriks 2013; Uzquiano 2004) or account for it through mereological views of constitution (Harris 2020), which run into the same aforementioned problem. 
I conclude that a strictly non-mereological constitution account of the material existence of group agents is the most explanatorily successful since it is the only proposal that can meet the non-transitivity desideratum of group agents. 

Beginning from Rudolf Carnap’s well known thesis that ontological commitment is internal to linguistic frameworks, I argue that this view can be considerably enriched by exploring the varied, and sometimes complex, relations between frameworks.  In this paper, I set out the basic features of these relations between frameworks – a relativity of frameworks. Those features are illustrated by showing how they apply to two of the most debated issues in metaphysics and their related semantics: the status of fictional objects and the analysis of true negative existence statements.

Ontological nihilism is a philosophical position that denies the existence of anything. The central concept of this position is nothingness. The origins of ontological nihilism can be found in the Old Testament, in the book of Genesis: God created the world from nothing. I argue that ontological nihilism is contradictory and cannot be true. I will try to prove that nothingness is a fiction and that being is everywhere, because nothingness does not exist. The fictional concept of nothingness arises when existence is separated from being. Then existence is nothing because it arises and disappears. But disappearing does not mean becoming nothing, and arising does not mean arising from nothing. Being contains arising, becoming, and disappearing, which do not exist separately from it. When we say that “God created the world out of nothing,” we mean that God existed before the world and created it out of nothing, that is, out of non-being. Now, let us consider the rephrased biblical statement: “God-being creates being out of non-being.” This statement is contradictory. God, as the very equivalent of being, can only create being from being, that is, from what is, and not from what is not, that is, from non-being.

In the field of metaphysics concerned with causal powers (powers ontology) a central debate concerns whether all properties are powers, or whether some properties are nonpowerful. Some philosophers argue that we need inert (nonpowerful) properties called categorical properties or qualities in order to avoid problematic regresses that emerge if we have a powers-only ontology. In this paper, I argue that all properties are powerful. I propose that what seem like inert properties are powers-in-act, i.e. manifesting powers. I define powers as starting points of change which can be potentialities for motion and change, or already manifesting powers. This definition is in contrast to mainstream definitions in the powers literature wherein powers are defined as mere potentialities, that, when manifested, are replaced by other potentialities. I argue that my definition of powers helps us resolve the regresses normally associated with powers-only ontologies. 
Further, some philosophers have suggested that phenomenal properties (qualia) are paradigmatic categorical properties because they are not potentialities to do anything beyond the experience itself. I suggest in this paper that phenomenal properties are manifestations of potentialities that are nonproductive (i.e., powers that have no end extrinsic to the manifestation of the power). Nonproductive properties are not categorical properties, but manifestations of powers. As such, even phenomenal properties are powers.