Jessica M. Wilson

(Note: this is the lead article in a forthcoming issue of <em>Australasian Philosophical Review</em> edited by Dana Goswick, with comments by Karen Bennett, Ricki Bliss, Kerry McKenzie, Jonathan Schaffer, and others. A wide range of scientific, religious/cosmological, and philosophical views presuppose that there is what I call `metaphysical structure', whereby (i) some goings-on in a given domain D are (absolutely or comparatively) fundamental; and (ii) (comparatively) non-fundamental goings-on in D metaphysically depend on (absolutely or comparatively) fundamental goings-on in D. Such presuppositions motivate two broadly metametaphysical questions: (i) what makes it the case that some goings-on in a domain D are (absolutely or comparatively) fundamental? and (ii) what makes it the case that (comparatively) non-fundamental goings-on in a domain D metaphysically depend on (absolutely or comparatively) fundamental goings-on in D? Here I advance my preferred 'Fundamentality First' package deal approach to metaphysical structure, which couples a primitivist approach to fundamentality with a pluralist approach to metaphysical dependence.

Are we in position to warrantedly establish whether a given artificial intelligence (AI) system is conscious? In short, can we warrantedly establish whether there is AI Consciousness (AIC)? We argue for a provisionally pessimistic answer—probably not—by attending to the traditional problem of other minds. For each of the main response strategies to this problem, we argue that even if the strategy works to establish that other humans and some non-human animals are conscious, the prospect of the strategy’s working to establish that there is AIC—and more generally, to establish whether there is AIC—is unlikely. The upshot is that there a distinctively difficult problem of other AI minds, whose lack of principled resolution is likely to undermine attempts to answer questions about the personal, moral, and agential status of AI systems.

We articulate a collection of desiderata for an account of the dynamical quantities of a physical theory, and we present a theory that meets these desiderata in the case of quantum mechanics. Our theory retains a distinction between the values of dynamical quantities and the truth values of sentences asserting that a system has a particular value of a particular quantity. This allows our theory to incorporate the phenomenon of quantum indeterminacy as a pattern in the properties instantiated by a system in a particular quantum state, while also retaining the semantics of classical logic. We contrast our theory with quantum logic, which flattens the distinction between quantity values and truth values, and we address a series of objections that have been raised to previous attempts to reconcile quantum indeterminacy with classical logic.

It is commonly supposed that metaphysical modal claims are to be evaluated with respect to a single domain of possible worlds: a claim is metaphysically necessary just in case it is true in every possible world, and metaphysically possible just in case it is true in some possible world. This chapter argues that the standard understanding is incorrect; rather, whether a given claim is metaphysically necessary or possible is relative to which world is _indicatively actual_. We motivate our view by attention to discussions in Salmon 1989 and Fine 2005, in which various data are taken to support rejecting the transitivity of accessibility (Salmon) and modal monism (Fine); we argue that relativized metaphysical modality can accommodate these data compatible with both standard modal logic(s) and modal monism. Noting an analogy with two-dimensional semantics, we argue that metaphysical modality has a complex structure, reflecting what is counterfactually possible, relative to each indicatively actual world.

It is often assumed that (rationally compelling, good) reasoning is defeasible if and only if it relies on an invalid argument, and that reasoning is indefeasible if and only if it relies only on valid arguments. We here argue that this common assumption is incorrect. We first argue that this equivalence should not be treated as definitional; we then argue that some reasoning is defeasible despite relying only on valid arguments, while other reasoning is indefeasible despite relying on invalid arguments. More specifically, we argue that deduction’s being subject to rebutting defeaters renders it defeasible, despite its relying only on valid arguments, while abduction’s being immune to rebutting defeaters renders it indefeasible, despite its relying on invalid arguments. We then offer an explanatory diagnosis of the errant assumption at issue, suggesting that it reflects both a too-quick generalization from the case of (enumerative) induction and a general tendency to conflate metaphysical and epistemic notions. Finally, we suggest that a kind of reasoning is an ultimate arbiter of disputes in a domain if and only if it is indefeasible in that domain, so that abduction is an ultimate arbiter of disputes in any domain in which it is operative.

I assess Zhong’s new “causal argument” for physicalism, which differs from previous such arguments in that the premises and conclusion pertain (not just to physical, but) to “physically acceptable” entities or features, which may be either physical or “grounded by” (i.e., metaphysically dependent on) the physical. Zhong argues that his new causal argument improves on previous versions in that the conclusion (unlike previous causal arguments, he maintains) supports non-reductive as well as reductive versions of physicalism, and in that the premises of his argument are better motivated than those of the original arguments. I argue that neither of these motivations are in place. Along the way, I offer a new reason to reject non-contrastive counterfactual accounts of causation.

I address the question of whether there is any role for metaphysics to play on which it is both non-redundant and capable of genuinely illuminating whatever subject matter is at issue. I first argue that metaphysical methodology itself obliges metaphysicians to take this question seriously. I then argue that the currently popular “hands-off” conception of metaphysical theorizing is unable to provide a satisfactory answer to the question of metaphysics. Third, I present my preferred “embedded” conception of metaphysics, and say why it makes good sense of metaphysics as a non-redundant discipline, capable of producing intelligible and illuminating results.

As Rodriguez-Pereyra understands the Problem of Universals, solving it requires specifying the truthmakers of attributions of sparse properties to particulars, so as to resolve the “Many over One”—the puzzle of how the same particular can be different ways. According to Rodriguez-Pereyra, these truthmakers need not involve irreducible properties ; resemblances between particulars will do. Here I’ll set out Rodriguez-Pereyra’s version of resemblance nominalism and note certain of its problems, some of which can be answered with revisions that he could, qua nominalist, accept, and others for which the solution is not so clear.

I discuss certain representative accounts of metaphysical emergence falling into three broad categories, assessing their prospects for satisfying certain criteria; the ensuing dialectic has a bit of the Goldilocks fable about it. At one end of the spectrum are what I call ‘scientistic’ accounts, which characterize metaphysical emergence by appeal to one or another specific feature commonly registered in scientific descriptions of seeming cases of emergence; such accounts, I argue, typically fail to provide a clear basis for ensuring incompatibility with ontological reduction, and thus fail to guarantee satisfaction of the criterion of appropriate contrast (§2). At the other end of the spectrum are what I call ‘abstractionist’ accounts, which characterize emergence in terms floating free of scientific notions; such accounts, I’ll argue, typically fail to guarantee satisfaction of the criterion of illuminating contrast (§3). I’ll then look at several accounts of metaphysical emergence that are what I call ‘substantive’, in appealing to familiar relations or posits which are properly metaphysical, while being intelligibly connected to scientific relations and posits. As we’ll see, the resources of such accounts are up to the tasks of blocking ontological reduction and of enabling investigations into metaphysical emergence to proceed in an illuminating way (§4). I close with some methodological morals (§5)

One might suppose that Everettian quantum mechanics (EQM) is inhospitable to metaphysial indeterminacy (MI), given that, as A. Wilson (2020) puts it, "the central idea of EQM is to replace indeterminacy with multiplicity" (77). But as Wilson goes on to suggest, the popular decoherence-based understanding of EQM (henceforth: DEQM) appears to admit of indeterminacy in both world number and world nature, where the latter indeterminacy---our focus here---is plausibly metaphysical. After a brief presentation of DEQM (S1), we bolster the case for there being MI in world nature in DEQM (S2). The remainder of the paper is devoted to a comparative assessment of the two main approaches to MI for purposes of accommodating this MI---namely, a metaphysical supervaluationist approach (as per Barnes and Williams 2011) and a determinable-based approach (as per Wilson 2013 and Calosi and Wilson 2018 and 2021). We briefly describe each approach (S3), then offer arguments in favour of a determinable-based approach to world nature MI in DEQM (S4).

Note: this is the first published presentation and defense of the 'proper subset strategy' for making sense of non-reductive physicalism or the associated notion of realization; this is sometimes, inaccurately, called "Shoemaker's subset strategy"; if people could either call it the 'subset strategy' or better yet, add my name to the mix I would appreciate it. Horgan claims that physicalism requires "superdupervenience" -- supervenience plus robust ontological explanation of the supervenient in terms of the base properties. I argue that Horgan's account fails to rule out physically unacceptable emergence. I rather suggest that this and other unacceptable possibilities may be ruled out by requiring that each individual causal power in the set associated with a given supervenient property be numerically identical with a causal power in the set associated with its base property. I go on to show that a wide variety of physicalist accounts, both reductive and non-reductive, are implicitly or explicitly designed to meet this condition, and so are more similar than they seem. In particular, non-reductive physicalism accounts typically appeal to a relation plausibly ensuring that the powers of a higher-level property are a proper subset of those of its physical base property.

Is there a need for a distinctively diachronic conception of metaphysical emergence? This chapter argues to the contrary. In the main, its argumentative strategy consists in considering a representative sample of accounts of purportedly diachronic metaphysical emergence, and arguing that in each case, the purportedly diachronic emergence at issue either can (and should) be subsumed under a broadly synchronic account of metaphysical emergence, or else is better seen as simply a case of causation. More specifically, it is argued that emergence as a diachronic causal phenomenon can be synchronically accommodated as involving emergent powers of a composite to produce the effects in question; that dynamic emergence can be synchronically accommodated as involving cotemporal dependence on a temporally extended base; that fusion/transformational emergence is plausibly just causation, subject to conditions standardly satisfied in cases of intra-level causation; and that ‘contextual’ emergence is plausibly just causation, where (as per usual) causes (or associated powers or dispositions) enter into producing effects only given the obtaining of relevant background conditions.

It is commonly supposed that metaphysical modal claims are to be evaluated with respect to a single domain of possible worlds: a claim is metaphysically necessary just in case it is true in every possible world, and metaphysically possible just in case it is true in some possible world. We argue that the standard understanding is incorrect; rather, whether a given claim is metaphysically necessary or possible is relative to which world is indicatively actual. We motivate our view by attention to discussions in Salmon 1989 and Fine 2005, in which various data are taken to support rejecting the transitivity of accessibility and modal monism ; we argue that relativized metaphysical modality can accommodate these data compatible with both standard modal logic and modal monism. Noting an analogy with two-dimensional semantics, we argue that metaphysical modality has a complex structure, reflecting what is counterfactually possible, relative to each indicatively actual world. In arguing for the need for relativization, we are broadly on the same side as Crossley and Humberstone and Davies and Humberstone ; our contribution here is, first, to offer distinctively metaphysical reasons for relativization, and second, to show that relativization can be incorporated in ways minimally departing from standard modal logic

The debate between exceptionalists and anti-exceptionalists about logic is often framed as concerning whether the justification of logical theories is a priori or a posteriori (for short: whether logic is a priori or a posteriori). As we substantiate (S1), this framing more deeply encodes the usual anti-exceptionalist thesis that logical theories, like scientific theories, are abductively justified, coupled with the common supposition that abduction is an a posteriori mode of inference, in the sense that the epistemic value of abduction is (and, indeed, must be) a posteriori. In past work, however, we have argued that this common supposition is incorrect: abduction is an a priori mode of inference, in the sense that the epistemic value of abduction is (and indeed, must be) a priori (Biggs and Wilson 2017a, 2017b, 2019). After sketching our two main argumentative strategies for this conclusion (S2), we go on (S3) to consider its import on the proper understanding of anti-exceptionalism about logic.

Inspired by Cantor's Theorem (CT), orthodoxy takes infinities to come in different sizes. The orthodox view has had enormous influence in mathematics, philosophy, and science. We will defend the contrary view---Countablism---according to which, necessarily, every infinite collection (set or plurality) is countable. We first argue that the potentialist or modal strategy for treating Russell's Paradox, first proposed by Parsons (2000) and developed by Linnebo (2010, 2013) and Linnebo and Shapiro (2019), should also be applied to CT, in a way that vindicates Countabilism. Our discussion dovetails with recent independently developed treatments of CT in Meadows (2015), Pruss (2020), and Scambler (2021), aimed at establishing the mathematical viability, and therefore epistemic possibility, of Countabilism. Unlike these authors, our goal isn't to vindicate the mathematical underpinnings of Countabilism. Rather, we aim to argue that, given that Countabilism is mathematically viable, Countabilism should moreover be regarded as true. After clarifying the modal content of Countabilism, we canvas some of Countabilism's many positive implications, including that Countabilism provides the best account of the pervasive independence phenomena in set theory, and that Countabilism has the power to defuse several persistent puzzles and paradoxes found in physics and metaphysics. We conclude that in light of its theoretical and explanatory advantages, Countabilism is more likely true than not.

In Calosi and Wilson (Phil Studies 2019/2018), we argue that on many interpretations of quantum mechanics (QM), there is quantum mechanical indeterminacy (QMI), and that a determinable-based account of metaphysical indeterminacy (MI), as per Wilson 2013 and 2016, properly accommodates the full range of cases of QMI. Here we argue that this approach is superior to other treatments of QMI on offer, both realistic and deflationary, in providing the basis for an intelligible explanation of the interference patterns in the double-slit experiment. We start with a brief overview of the motivations for QMI and for a determinable-based account of MI (§1). We then apply a developed 'glutty' implementation of determinable-based QMI to the superposition-based QMI present in the double-slit experiment, and positively compare the associated explanation of double-slit interference with that available on a metaphysical supervaluationist account of QMI (§2). We then present and respond to objections, due to Glick (2017) and Torza (2017), either to QMI (§3) or to our specific account of QMI (§4); in these sections we also positively compare our treatment of double-slit interference to that available on Glick's deflationary treatment of QMI. We conclude with some dialectical observations (§5).

Relativized Metaphysical Modality (RMM: Murray and Wilson, 'Relativized metaphysical modality', Oxford Studies in Metaphysics, 2012; Murray, Perspectives on Modal Metaphysics, 2017) exploits 'two-dimensionalist' resources to metaphysical, rather than epistemological, ends: the second dimension offers perspective-dependence without contingency, diverting attacks on 'Classical' analyses of modals (in effect, analyses validating S5 and the Barcan Formulae). Here, we extend the RMM program in two directions. First, we harvest resources for RMM from Lewis's 1980 'Context--Index' (CI) framework: (a) the ban in CI on binding into context-arguments (akin to Kaplan's 'monstrosity' ban) projects a bright line between perspective-dependence and contingency; and (b) CI-postulated connections among meaning, content, truth, argument-structure, context, and modality collectively generate a 'Generalized Humphrey Problem' for any non-Classical analysis (examples covered include appeals to accessibility, contingent domains, and counterpart relations). Second, we sharpen the tools of RMM-based metaphysical analysis, and extend their domain of coverage across familiar anomalies for Classical modals: we revisit earlier RMM-based bulwarks for S5 (against 'Chisholm's Paradox' for moderate flexibility of essence, and nomological necessitarianism); and we now similarly shore up the Barcan Formulae (against the apparent contingency of existence and nonexistence).

I problematize Grounding-based formulations of physicalism. More specifically, I argue, first, that motivations for adopting a Grounding-based formulation of physicalism are unsound; second, that a Grounding-based formulation lacks illuminating content, and that attempts to imbue Grounding with content by taking it to be a strict partial order are unuseful and problematic ; third, that conceptions of Grounding as constitutively connected to metaphysical explanation conflate metaphysics and epistemology, are ultimately either circular or self-undermining, and controversially assume that physical dependence is incompatible with explanatory gaps; fourth, that in order to appropriately distinguish physicalism from strong emergentism, a Grounding-based formulation must introduce one and likely two primitives in addition to Grounding; and fifth, that understanding physical dependence in terms of Grounding gives rise to ‘spandrel’ questions, including, e.g., “What Grounds Grounding?”, which arise only due to the overly abstract nature of Grounding.

Mary Shepherd (1777–1847) was a fierce and brilliant critic of Berkeley and Hume, who moreover offered strikingly original positive views about the nature of reality and our access to it which deserve much more attention (and credit, since she anticipates many prominent views) than they have received thus far. By way of illustration, I focus on Shepherd's 1824 Essay Upon the Relation of Cause and Effect, Controverting the Doctrine of Mr. Hume, Concerning the Nature of that Relation (ERCE). After a brief setup, I canvas certain of her trenchant objections to Hume’s argumentation; I then present the positive core of her response to Hume, which consists in providing novel accounts of how reason alone or reason coupled with experience can justify, first, that every effect must have a cause, and second, that it is necessary that like causes produce like effects. Among other contributions here, Shepherd provides a distinctively metaphysical argument for the claim that nothing can begin to exist 'of itself' (going beyond an appeal to the Principle of Sufficient Reason, in particular), and leverages difference-making considerations to make the case that a single 'experimentum crucis' can justify causal belief (anticipating Mill's 'method of difference'). I close by highlighting salient features of Shepherd's metaphysics of causation, whereby causation is singularist and local (anticipating Ducasse and Anscombe) and involves synchronic interactions (anticipating Mill's and certain contemporary accounts), and according to which objects are essentially characterized by their causes and effects (anticipating contemporary causal or dispositional essentialist positions).

Both the special sciences and ordinary experience suggest that there are metaphysically emergent entities and features: macroscopic goings-on (including mountains, trees, humans, and sculptures, and their characteristic properties) which depend on, yet are distinct from and distinctively efficacious with respect to, lower-level physical configurations and features. These appearances give rise to two key questions. First, what is metaphysical emergence, more precisely? Second, is there any metaphysical emergence, in principle and moreover in fact? Metaphysical Emergence provides clear and systematic answers to these questions. Wilson argues that there are two, and only two, forms of metaphysical emergence of the sort seemingly at issue in the target cases: 'Weak' emergence, whereby a dependent feature has a proper subset of the powers of the feature upon it depends, and 'Strong' emergence, whereby a dependent feature has a power not had by the feature upon which it depends. Weak emergence unifies and illuminates seemingly diverse accounts of non-reductive physicalism; Strong emergence does the same as regards seemingly diverse anti-physicalist views positing fundamental novelty at higher levels of compositional complexity. After defending the in-principle viability of each form of emergence, Wilson considers whether complex systems, ordinary objects, consciousness, and free will are actually metaphysically emergent. She argues that Weak emergence is quite common, and that there is Strong emergence in the important case of free will.

This correction reflects that I forgot to cite Stephan Leuenberger's unpublished work in the paragraph beginning "More promising, perhaps, is the orthodox view ..." in Section 5. The overall argument of Section 5 is a development of an argument I gave in footnote 27 of 'No Work for a Theory of Grounding' (Inquiry, 2014). At issue in the relevant sections of 'No Work...' and 'Grounding-based Formulations...' is whether a proponent of Grounding has resources to accommodate strongly emergent phenomena, where strong emergence is understood as contrasting with physicalism. In 'No Work...', after arguing in the text that an account of strong emergence as involving a failure of full Grounding would not accommodate the live possibility that strongly emergent goings-on might be partially but not completely metaphysically dependent on physical goings on, I considered in note 27 whether strong emergence, again understood as contrasting with physicalism, could be characterized by appeal to a Finean notion of partial Grounding, as the view that strongly emergent goings-on are partially but not fully Grounded in physical goings-on, and I argued that assuming that the notion of partial Grounding was taken to be primitive, then (since there were no prospects of defining full Grounding in terms of primitive partial Grounding along lines of defining a general notion of parthood in terms of primitive proper parthood or identity), such an approach would require that full Grounding also be taken as primitive, with possibly yet another primitive connecting partial and full Grounding. I heard Leuenberger's talk 'Emergence and Failures of Supplementation' in May 2015; for purposes of developing my previous argument (as per Section 5 in 'Grounding-based Formulations...') this talk was helpful since Leuenberger correctly argued that there were also no prospects for implementing the partial Grounding-based strategy by taking full Grounding to be primitive and defining partial Grounding in terms of full Grounding, since that would import a weak supplementation structure that might not be present in cases of strong emergence. I wrote to Leuenberger asking for his slides so that I could reference him and his work (which again is presented in the paragraph beginning "More promising, perhaps, is the orthodox view..."), but somehow forgot to include a citation to his talk, for which I sincerely apologize. One last thing: the erratum is a bit misleading about my use of Leuenberger's work. My discussion of whether a primitivist (i.e., 'non-orthodox') understanding of Finean partial Ground serves as a suitable basis for a partial Grounding-based approach to strong emergence stems from footnote 27 of my 2014, not Leuenberger's 2015 talk, and in both 'No Work...' and 'Grounding-based Formulations...' I argue that such an approach would be problematic, not "suitable", since involving two or three primitives. Also worth noting is that I do not claim or argue that the orthodox conception of partial Grounding as defined in supplementary fashion in terms of full Grounding is *incompatible* with strong emergence. Again, at issue in both 'No Work...' and in 'Grounding-based Formulations...' is strong emergence understood as contrasting with physicalism, so the relevant application of a partial Grounding-based strategy, whether or not involving an 'orthodox' account of partial Grounding as definable in terms of full Grounding, is in my papers one according to which strongly emergent goings-on are partially but not fully Grounded in *physical* goings-on. So far as I can tell, there might be cases of strong emergence that *do* obey supplementation, and which would be compatible with a partial Grounding-based account of strong emergence, where the operative notion of partial Grounding is 'orthodox' (non-primitive). For my purposes, what is important is that cases of strong emergence might not obey supplementation.