Is the world internally connected by a web of necessary connections or is everything loose and independent? Followers of David Hume accept the latter by upholding Hume’s Dictum, according to which there are no necessary connections between distinct existences. Roughly put, anything can coexist with anything else, and anything can fail to coexist with anything else. Hume put it like this: “There is no object which implies the existence of any other if we consider these objects in themselves.” Since Hume’s (...) day, Hume’s Dictum has played a major role in philosophy, especially in contemporary metaphysics. In ruling out necessary connections, Hume’s Dictum implies that causal relations and the laws of nature are contingent. It makes other demands on our metaphysics of science as well; for example, it places restrictions on our metaphysics of counterfactuals, dispositions, and explanation. The principle has applications in other areas too. Hume’s Dictum places constraints on our theories of abstract objects and moral properties. For example, Hume’s Dictum rules out the view that moral properties are distinct from, but necessarily connected to, non-moral properties. While Hume’s Dictum is a prominent principle in metaphysics, few Humeans have defended the principle at length. It is assumed more often than it is argued for. As a result, Hume’s Dictum no longer enjoys the reputation it once did. It’s common to hear complaints about the lack of arguments in support of Hume’s Dictum. Moreover, philosophers are increasingly willing to defend views that are at odds with Hume’s Dictum. A striking example of this is the recent explosion of interest in views that take causal relations and the laws of nature to be necessary. Humeans can no longer afford to be complacent. An extended defense of Hume’s Dictum is called for, and that’s what this dissertation aims to offer. This dissertation has three parts. In the first part, I lay out some preliminaries and offer a precise formulation of Hume’s Dictum. In the second part, I develop three arguments in favor of Hume’s Dictum. In the final part, I defend Hume’s Dictum against objections. (shrink)

We draw out significant consequences of a relatively popular theory of metaphysical modality—branching actualism—for cosmological arguments for God’s existence. According to branching actualism, every possible world shares an initial history with the actual world and diverges only because causal powers (or dispositions, or some such) are differentially exercised. We argue that branching actualism undergirds successful responses to two recent cosmological arguments: the Grim Reaper Kalam argument and a modal argument from contingency. We also argue that branching actualism affords a response (...) to one popular defense of the classic contingency argument. What results are new difficulties for several cosmological arguments arising from the metaphysics of modality. (shrink)

Inspired by the third chapter of Anselm's Proslogion, twentieth century philosophers including Charles Hartshorne and Alvin Plantinga developed “modal” ontological arguments for the existence of God. Such arguments use modal logic to infer God's existence from the premises that (i) God's existence is possible and (ii) if God exists, He exists necessarily. Like other ontological arguments, modal arguments have won few converts to theism; many commentators consider them question‐begging or liable to parody. This article details how recent attempts to defend (...) these arguments have tried to overcome these difficulties by drawing on modern accounts of the epistemology and metaphysics of modality. (shrink)

Modal epistemologies that rely on a fallibilism about modal claims have been gaining traction over the years. This paper critically discusses the accounts of Kung (2009, 2010, 2016) and Dohrn (2018, 2019, 2020b) and argues that they are invariably susceptible to being read as entailing claims of epistemic possibility. Both Kung and Dohrn seek to ground modal intuitions on non‐modal ones, and primarily appeal to the modalizing capacity of imagination to aid in the discovery of modal truths. However, insofar as (...) inference from non‐modal imagination to modal truths remains fallible, then no non‐ad hocdistinction can be made between substantiation of fallible metaphysically modal claims and infallible epistemically modal ones. This is because, barring an agent's infallible knowledge of modal truths, how these truths are argued for must attend the agent's imperfect epistemic access thereof, therefore entailing claims of modality consistent with her epistemic state—that is, claims of epistemic possibility. If modal epistemologies in general non‐modally ground their modal assertions in this fallible fashion, then they seem inevitably interpretable in terms of epistemic possibility as opposed to some non‐epistemic reading of metaphysical possibility. (shrink)

Some philosophers defend the possibility of synchronic multilocation, and have even used it to defend other substantive metaphysical theses. But just how strong is the case for the possibility of synchronic multilocation? The answer to this question depends in part on whether synchronic multilocation is wedded to other controversial metaphysical notions. In this paper, I consider whether the possibility of synchronic multilocation depends on the possibility of time travel, and I conclude that the answer hinges on the nature of time (...) and persistence. (shrink)

Philosophy Compass, Volume 17, Issue 7, July 2022.

Causal essentialists hold that a property essentially bears its causal and nomic relations. Further, as many causal essentialists have noted, the main motivations for causal essentialism also motivate holding that properties are individuated in terms of their causal and nomic relations. This amounts to a kind of identity of indiscernibles thesis; properties that are indiscernible with respect to their causal and nomic relations are identical. This can be compared with the more well-known identity of indiscernibles thesis, according to which particulars (...) that are qualitatively indiscernible are identical. Robert Adams has developed a well-known objection to this thesis by considering a series of possibilities involving nearly qualitatively indiscernible particulars that naturally leads to a possibility involving qualitatively indiscernible particulars. I argue that we can construct parallel cases involving a series of possibilities involving properties that are nearly indiscernible with respect to their causal and nomic relations that naturally lead to possibilities involving properties that are indiscernible with respect to their causal and nomic relations. The same features that make Adams’ argument forceful also carry over to my cases, giving us a powerful objection to the causal essentialist identity of indiscernibles thesis. (shrink)

Many philosophers since Hume have accepted that imagining/conceiving a scenario is our prime guide to knowing its possibility. Stephen Yablo provided a more systematic criterion: one is justified in judging that p is possible if one can imagine a world which one takes to verify p. I defend a version of Yablo’s criterion against van Inwagen’s moderate modal scepticism. Van Inwagen’s key argument is that we cannot satisfy Yablo’s criterion because we are not in a position to spell out far-fetched (...) possible scenarios in relevant detail. Van Inwagen’s argument can be applied to the use of conceivability for everyday possibility claims, leaving us with the spectre of pervasive modal scepticism. In order to answer the sceptical threat, I combine van Inwagen’s main example with general considerations about the nature of metaphysical modality to motivate a version of Yablo’s criterion and show that it does not lead to scepticism. One structural condition of p being metaphysically possible is that it coheres with a complete reality. This condition gives rise to Yablo’s criterion. However, for the criterion to be of any avail, we have to disregard details we are not in a position to specify. To account for our practice of doing so, I use Yablo’s distinction between imagining a world as determinate and imagining it determinately. I present a condition when we may simply disregard details as determinate. The condition results from integrating analogical reasoning into the conceivability test. (shrink)

How should modal reasoning proceed? Here we compare abduction-based and conceiving-based modal epistemologies, and argue that an abduction-based approach is preferable, and by a wide margin.

The present work explores various ways in which contingent evidence can impact metaphysics, while advocating that, just as a scientific realist allows for ampliative inferences to the unobservable, ampliative inferences from possible evidence can warrant possibility claims that lie beyond the reach of sensorial imagination. In slogan form: possible evidence is a guide to possibility. Drawing on Shoemaker’s (1969) argument for the possibility of time without change, I advocate the following principle: If there is a possible world at which the (...) observable facts make it objectively reasonable to conclude that p, then we should conclude that p is possibly true. This provides a route to contingentism in metaphysics, for, if one considers that there are worlds in which the observable facts make it objectively reasonable to conclude that p, and worlds in which the observable facts make it objectively reasonable to conclude that not-p, then my principle tells us that we should conclude that possibly-p and possibly not-p, i.e. that p is contingent. This contingency in what is reasonable to conclude, I suggest, occurs most saliently in debates where evidence of phenomenal experience and empirical science are marshalled to support one theory over another. I also explore some consequences of taking possible evidence to be a guide to possibility in this way, among them being an interesting modal analogue of the lottery paradox. (shrink)

Accounts of modal knowledge are many and varied. How should we choose between them? I propose that we employ inference to the best explanation, and I suggest that there are three desiderata that we should use to rank hypotheses: conservatism, simplicity, and the ability to handle disagreement. After examining these desiderata, I contend that they can’t be used to justify belief in the modal epistemology that fares best, but that they can justify our accepting it in an epistemically significant sense. (...) Finally, I outline a modal epistemology that seems to do well by the standards I’ve recommended. (shrink)