The philosophy of necessity and possibility has flourished in the last half-century, but much less attention has been paid to the question of how we know what can be the case and what must be the case. Many friends of modal metaphysics and many enemies of modal metaphysics have agreed that while empirical discoveries can tell us what is the case, they cannot shed much light on what must be the case or on what non-actual possibilities there are. In this (...) paper, in contrast, I discuss and defend naturalistic approaches to discovering the facts about necessity and possibility. After some remarks about what methodological naturalism in philosophy might amount to, I argue that naturalistic method in modal investigations may not need to be particularly revisionary of much of what is currently being done in modal investigation. I then discuss a number of respects in which a naturalistic orientation in modal investigation may improve on our current epistemic situation. (shrink)

In May 1999, David Lewis sent Timothy Williamson an intriguing letter about knowledge and vagueness. This paper has a brief discussion of Lewis on evidence, and a longer discussion of a distinctive theory of vagueness Lewis puts forward in this letter, one rather different from standard forms of supervaluationism. Lewis's theory enables him to provide distinctive responses to the challenges to supervaluationism famously offered in chapter 5 of Timothy Williamson's 1994 book Vagueness. However these responses bring out a number of (...) very surprising features of Lewis's own view. -/- The letter from Lewis itself is available on the blog of The Age of Metaphysical Revolution Project, University of Manchester. (shrink)

Readers of fictions sometimes resist taking certain kinds of claims to be true according to those fictions, even when they appear explicitly or follow from applying ordinary principles of interpretation. This "imaginative resistance" is often taken to be significant for a range of philosophical projects outside aesthetics, including giving us evidence about what is possible and what is impossible, as well as the limits of conceivability, or readers' normative commitments. I will argue that this phenomenon cannot do the theoretical work (...) that has been asked of it. Resistance to taking things to be fictional is often best explained by unfamiliarity with kinds of fictions than any representational, normative, or cognitive limits. With training and experience, any understandable proposition can be made fictional and be taken to be fictional by readers. This requires a new understanding both of imaginative resistance, and what it might be able to tell us about topics like conceivability or the bounds of possibility. (shrink)

This paper discusses an infinite regress that looms behind a certain kind of historical explanation. The movement of one barbarian group is often explained by the movement of others, but those movements in turn call for an explanation. While their explanation can again be the movement of yet another group of barbarians, if this sort of explanation does not stop somewhere we are left with an infinite regress of barbarians. While that regress would be vicious, it cannot be accommodated by (...) several general views about what viciousness in infinite regresses amounts to. This example is additional evidence that we should prefer a pluralist approach to infinite regresses. (shrink)

Creationism about fictional entities requires a principle connecting what fictions say exist with which fictional entities really exist. The most natural way of spelling out such a principle yields inconsistent verdicts about how many fictional entities are generated by certain inconsistent fictions. Avoiding inconsistency without compromising the attractions of creationism will not be easy.

A standing challenge in the theory of counterfactuals is to solve the “deviation problem”. Consider ordinary counterfactuals involving an antecedent concerning a difference from the actual course of events at a particular time, and a consequent concerning, at least in part, what happens at a later time. In the possible worlds framework, the problem is often put in terms of which are the relevant antecedent worlds. Desiderata for the solution include that the relevant antecedent worlds be governed by the actual (...) laws of nature with no miracles; that the past in those worlds before the antecedent time matches the actual past; that the account is compatible with determinism, and that many of our ordinary counterfactual judgments are correct, and would be correct even given determinism. Many theorists have compromised on one or more of these desiderata, but this paper presents an account employing impossible worlds that satisfies them all. (shrink)

One of the standard approaches to the metaphysics of personal identity has some counter-intuitive ethical consequences when combined with maximising consequentialism and a plausible doctrine about aggregation of consequences. This metaphysical doctrine is the so-called ‘multiple occupancy’ approach to puzzles about fission and fusion. It gives rise to a new version of the ‘utility monster’ problem, particularly difficult problems about infinite utility, and a new version of a Parfit-style ‘repugnant conclusion’. While the article focuses on maximising consequentialism for simplicity, the (...) problems demonstrated apply more widely to a range of ethical views, especially flavours of consequentialism. This article demonstrates how these problems arise, and discusses a number of options available in the light of these problems for a consequentialist tempted by a multiple occupancy metaphysics. (shrink)

_ Source: _Volume 10, Issue 3, pp 441 - 456 Several kinds of historical alternatives are distinguished. Different kinds of historical alternatives are valuable to the practice of history for different reasons. Important uses for historical alternatives include representing different sides of historical disputes; distributing chances of different outcomes over alternatives; and offering explanations of why various alternatives did _not_ in fact happen. Consideration of counterfactuals about what would have happened had things been different in particular ways plays particularly useful (...) roles in reasoning about historical analogues of current conditions; reasoning about causal claims; and in evaluating historical explanations. When evaluating the role of alternative histories in historical thinking, we should keep in mind the uses of historical alternatives that go well beyond the long-term and specific scenarios that are the focus of so-called “counterfactual history”. (shrink)

We reply to recent papers by John Turri and Ben Bronner, who criticise the dispositionalised Nozickian tracking account we discuss in “Mad, Bad and Dangerous to Know.” We argue that the account we suggested can handle the problems raised by Turri and Bronner. In the course of responding to Turri and Bronner’s objections, we draw three general lessons for theories of epistemic dispositions: that epistemic dispositions are to some extent extrinsic, that epistemic dispositions can have manifestation conditions concerning circumstances where (...) their bearers fail to exist, and that contrast is relevant to disposition attributions. (shrink)

This chapter provides an introduction to possible worlds semantics in both logic and the philosophy of language, including a discussion of some of the advantages and challenges for possible worlds semantics.

Curry's paradox for "if.. then.." concerns the paradoxical features of sentences of the form "If this very sentence is true, then 2+2=5". Standard inference principles lead us to the conclusion that such conditionals have true consequents: so, for example, 2+2=5 after all. There has been a lot of technical work done on formal options for blocking Curry paradoxes while only compromising a little on the various central principles of logic and meaning that are under threat. -/- Once we have a (...) sense of the technical options, though, a philosophical choice remains. When dealing with puzzles in the logic of conditionals, a natural place to turn is independently motivated semantic theories of the behaviour of "if... then...". This paper argues that the closest-worlds approach outlined in Nolan 1997 offers a philosophically satisfying reason to deny conditional proof and so block the paradoxical Curry reasoning, and can give the verdict that standard Curry conditionals are false, along with related "contraction conditionals". (shrink)

This paper explores a special kind of loop of grounding: cosmic loops. A cosmic loop is a loop that intuitively requires us to go "around" the entire universe to come back to the original ground. After describing several kinds of cosmic loop scenarios, I will discuss what we can learn from these scenarios about constraints on grounding; the conceivability of cosmic loops; the possibility of cosmic loops; and the prospects for salvaging local reflexivity, asymmetry and transitivity of grounding in a (...) world containing a cosmic loop of ground. The considerations raised in this paper also bear on what we should think about relations that are meant to support grounding relations: in particular, revisions to theories of the part-whole relation are discussed. (shrink)

Methodological naturalism arises as a topic in metaethics in two ways. One is the issue of whether we should be methodological naturalists when doing our moral theorising, and another is whether we should take a naturalistic approach to metaethics itself. Interestingly, these can come apart, and some naturalist programs in metaethics justify a non-scientific approach to our moral theorising. This paper discusses the range of approaches that fall under the general umbrella of methodological naturalism, and how naturalists view the role (...) of science in ethics and metaethics. It discusses how naturalism interacts with the use of intuitions, using conceptual analysis, and reflective equilibrium methods. Finally, it discusses some ways using scientific investigation can make distinctive contributions to ethics and metaethics. (shrink)

A principle endorsed by many theories of objective chance, and practically forced on us by the standard interpretation of the Kolmogorov semantics for chance, is the principle that when a proposition P has a chance, any proposition Q that is necessarily equivalent to P will have the same chance as P. Call this principle SUB (for the substitution of necessary equivalents into chance ascriptions). I will present some problems for a theory of chance, and will argue that the best way (...) to resolve these problems is to reject SUB, and similar principles e.g. for the chances of outcomes or the chances of events. Objective chance, it turns out, carves things more finely than necessary equivalence does. (shrink)

In Metaphysics A, Aristotle offers some objections to Plato’s theory of Forms to the effect that Plato’s Forms would not be explanatory in the right way, and seems to suggest that they might even make the explanatory project worse. One interesting historical puzzle is whether Aristotle can avoid these same objections to his own theory of universals. The concerns Aristotle raises are, I think, cousins of contemporary concerns about the usefulness and explanatoriness of abstract objects, some of which have recently (...) been receiving attention in the philosophy of mathematics. After discussing Aristotle’s objections and their contemporary cousins, the paper discusses some of the main available lines of response to these sorts of challenges, before concluding with an examination of whether these responses could assist Plato or Aristotle in responding to these challenges. (shrink)

Parties to a temporary marriage agree in advance that their marriage will only last for a fixed period of time unless renewed: that it will automatically expire after two years, for instance, or five, or twenty. This paper defends the claim that temporary marriages deserve state recognition. The main argument for this is an application of a principle of marriage equality. Some other arguments for are also canvassed, including an argument from religious freedom, and a number of arguments against recognition (...) are also discussed. The paper also discusses the question of whether such “temporary marriages” are in fact a kind of marriage, and defends the claim that they are, or would be, genuinely marriages. (shrink)

This paper makes a case that we should believe in the existence of worldly states of affairs.

Chrysippus often talks as if there is a third option when we might expect that two options in response to a question are exhaustive. Things are true, false or neither; equal, unequal, or neither; the same, different, or neither.. and so on. There seems to be a general pattern here that calls for a general explanation. This paper offers a general explanation of this pattern, preserving Stoic commitments to excluded middle and bivalence, arguing that Chrysippus employs this trichotomy move when (...) he wishes to argue that apparent contradictories are only contraries, and wishes to endorse a third option. This general explanation of the pattern of trichotomies sheds light on a number of interpretive puzzles, including on Chrysippus's response to the paradox of the cone. The purpose of these trichotomies is also discussed, and it is suggested that they originate from the dialectical context in which philosophical problems were posed. (shrink)

This paper builds on the system of David Lewis’s “Parts of Classes” to provide a foundation for mathematics that arguably requires not only no distinctively mathematical ideological commitments (in the sense of Quine), but also no distinctively mathematical ontological commitments. Provided only that there are enough individual atoms, the devices of plural quantification and mereology can be employed to simulate quantification over classes, while at the same time allowing all of the atoms (and most of their fusions with which we (...) are concerned) to be individuals (that is, urelements of classes). The final section of the paper canvasses some reasons to be committed to the required ontology for other than mathematical reasons. (shrink)