It is widely assumed that sense perception cannot deliver knowledge of nonactual (metaphysical) possibilities. We are not supposed to be able to know that a proposition p is necessary or that p is possible (if p is false) by sense perception. This paper aims to establish that the role of sense perception is not so limited. It argues that we can know lots of modal facts by perception. While the most straightforward examples concern possibility and contingency, others concern (...) necessity and impossibility. The possibility of a perceptual route to some modal knowledge is not as radical as it may at first sound. On the contrary, acknowledging it has benefits. (shrink)

In 1947 Quine wrote one of the most important and influential articles in the twentieth century philosophy - "On What There Is". One of the aims of this article was a critique of Meinong's Theory of Object. The critique was especially focused upon nonactual possibilities, which (according to Meinong) are some kinds of nonexistent objects. In my paper I want to present Neo-Meinongian refutations of Quine's critique. In order to do this I discuss: (i) the main thesis of (...) "On What There Is" ,(ii) premises of Meinongian Theory, (iii) views of proponents and opponents of the idea of nonexistent objects, (iv) Quine's critique aimed at nonactual possibilities, (v) Terence Parsons' theory, based on the distinction between nuclear and extranucler properties, and (vi) noneism, defended by Richard Routley. I also try to give a reply to the most popular critiques aimed at both Neo-Meinongian theories. The main conclusion is that Quine's critique and his arguments against nonactual possibilities aren't dangerous for theories endorsing Meinong's Theory of Object. Contrary to what Gilbert Ryle once claimed (If Meinongianism isn't dead, nothing is), Meinongian theories are still alive and doing well. (shrink)

Robert Adams characterizes actualism regarding possible worlds as «the view that if there are any true statements in which there are said to be nonactual possible worlds, they must be reducible to statements in which the only things there are said to be are things which there are in the actual world, and which are not identical with nonactual possibles.» In this paper, I will briefly explain actualism about possible worlds, showing that an essential pillar of the theory (...) is the claim that truth is distinct from, and ontologically prior to, truth in a world. The rest of the paper is premised on the idea that an interesting philosophical defense of this claim calls for an analysis of truth itself, and is not intended as an objection to actualism, but rather to underscore the interest actualists should have in the question of what truth is. First, I will consider the idea, drawn from Adams and Alan McMichael, that truth differs from truth in a world in its being a matter of correspondence between a proposition and an independent object; that object being, in McMichael's words, the `concrete universe'. Then, I will show that, given such an analysis of truth, the truth conditions for propositions about non-actual possibilities violate the central tenet of actualism, as articulated by Adams. (shrink)

Sometimes, scientific models are either intended to or plausibly interpreted as representing nonactual but possible targets. Call this “hypothetical modeling”. This paper raises two epistemological challenges concerning hypothetical modeling. To begin with, I observe that given common philosophical assumptions about the scope of objective possibility, hypothetical models are fallible with respect to what is objectively possible. There is thus a need to distinguish between accurate and inaccurate hypothetical modeling. The first epistemological challenge is that no account of the epistemology (...) of hypothetical models seems to cohere with the most characteristic function of scientific modeling in general, i.e., surrogative representation. The second epistemological challenge is a version of “reliability challenges” familiar from other areas. There is a challenge to explain how hypothetical models could be a reliable guide to what is possible, given that they are not and cannot be compared against their nonactual targets and updated accordingly. I close with some brief remarks on possible solutions to these challenges. (shrink)

This essay challenges the widely accepted principle that a person is morally responsible for what he has done only if he could have done otherwise. The author considers situations in which there are sufficient conditions for a certain choice or action to be performed by someone, So that it is impossible for the person to choose or to do otherwise, But in which these conditions do not in any way bring it about that the person chooses or acts as he (...) does. In such situations the person may well be morally responsible for what he chooses or does despite his inability to choose or to do otherwise. Finally the author considers certain suggestions for revising the principle he rejects or for replacing it with a principle of an altogether different kind. (shrink)

Drawing upon the life and work of S. Kay Toombs, I explore the impact and import of phenomenological accounts of disability for the existentialist tradition. Through the case of multiple sclerosis, a noncongenital, late-onset, and degenerative disability, I show how the general structures that emerge from its lived experience largely support a mere-difference view of disability and highlight the need for an equitably habitable world. I further argue that phenomenological accounts of disability demonstrate accessibility to be the defining feature of (...) what it means to be embodied as we are. I conclude with a discussion of the more general philosophical relationship between disability, embodiment, and existentialism. (shrink)

Our moral obligations can sometimes be collective in nature: They can jointly attach to two or more agents in that neither agent has that obligation on their own, but they – in some sense – share it or have it in common. In order for two or more agents to jointly hold an obligation to address some joint necessity problem they must have joint ability to address that problem. Joint ability is highly context-dependent and particularly sensitive to shared (or even (...) common) beliefs. As such, joint ability can be deliberately generated in a given collection of agents by providing information related to collective goals and contributory actions. As moral agents, we regularly face problems wherein the outcome of our actions depends on how others choose. There are two ways of deliberating about our own choices in such cases. We can either think of our choices as best responses to others’ choices (I-mode reasoning). Or we can think of our own choices as contributions to the collectively best option (even when we do not know how others are (likely) to choose) (we-mode reasoning). In deliberating about the right (individual) course of action vis-à-vis collective action problems, agents regularly we-frame the case at hand, that is, they include options in their deliberation that are only collectively available, and they we-reason with regard to their individual contributory actions. It is a necessary condition for collective obligations that potential collaborators facing a joint necessity case have grounds to privilege we-reasoning over reasoning in I-mode. (shrink)

Recent work in the philosophy of emotion focuses on challenging dualistic conceptualizations. Three of the most obvious dualisms are the following: 1. emotion opposes reason; 2. emotion is subjective, while reason is objective; 3. emotion lies internal to the subject, while reason is external. With challenges to these dualisms, one of the more interesting questions that has surfaced is the idea of emotional appropriateness in a particular context. Here, consider a widely held belief in the United States associates racialized groups (...) with specific emotions—most notably African American women with anger. Clearly these emotional attributions are essentialistic--and hence racist. But this response is too easy. The acknowledgement that emotion lies both internally in the subject and externally in the world opens the possibility of attributing an emotional temperament to a population group. Yet if an identity group has an emotional temperament, can they be accountable for emotionally appropriate behavior? (shrink)

Internalism holds that epistemic justification is determined by what is internal to the mind, not by facts about the mind-independent world. This paper introduces and defends a new kind of internalism that is rooted in rationalist ideas that have been neglected in recent epistemology, despite inspiring internalist projects in cognitive science. Ignoring rationalist insights has, I argue, damaged the prospects for internalism, by needlessly saddling internalists with empiricist burdens. Internalists can refuse these burdens by accepting a better philosophy of mind. (...) Rather than looking to 17th century rationalists, I look to Kant, and especially his idea that normativity is grounded in the constitution of agency and mind. A Kantian approach can avoid stock objections to internalism, I argue, and can also capture all the alleged benefits of externalism. The paper is structured as follows. In §2, I get back to basics and consider more ways to satisfy the core internalist template than have become standard. I draw attention to rationalist insights about how normativity could be grounded in the constitution of mind, and hypothesize that if internalism respects these insights, some problems disappear. I develop this hypothesis in §3 with a Kantian view. I further defend this view in §4. I conclude in §5 by explaining why Kantian internalism answers the latest challenges to internalism. (shrink)

This paper is inspired by and develops on E. J. Lowe’s work, who writes in his book The Possibility of Metaphysics that ‘metaphysical possibility is an inescapable determinant of actuality’ (1998: 9). Metaphysics deals with possibilities – metaphysical possibilities – but is not able to determine what is actual without the help of empirical research. Accordingly, a delimitation of the space of possibilities is required. The resulting – controversial – picture is that we generally need to know (...) whether something is possible before we can know whether it is actual. In order to appreciate this picture, we need to understand Lowe’s slogan: ‘essence precedes existence’ (Lowe 2008: 40). This slogan has both an ontological and an epistemic reading. The ontological reading is related to the now familiar idea that essence grounds modality, as popularised by Kit Fine. The epistemic reading suggests that we can know the essence of some entity before we know whether or not that entity exists. However, this idea is often met with puzzlement and Lowe himself sadly passed away before he had a chance to clarify this framework. I will present the framework as I understand it, develop it on my own terms, and put forward a qualified defence of it. I will also illustrate how the framework can be put to use with a case study concerning the discovery of transuranic elements. (shrink)

This paper was chosen by The Philosopher’s Annual as one of the ten best articles appearing in print in 2000. Reprinted in Volume XXIII of The Philosopher’s Annual. In his very influential book David Chalmers argues that if physicalism is true then every positive truth is a priori entailed by the full physical description – this is called “the a priori entailment thesis – but ascriptions of phenomenal consciousness are not so entailed and he concludes that Physicalism is false. As (...) he puts it, “zombies” are metaphysically possible. I attempt to show that this argument is refuted by considering an analogous argument in the mouth of a zombie. The conclusion of this argument is false so one of the premises is false. I argue at length that this shows that the original conceivability argument also has a false premise and so is invalid. (shrink)

David Lewis holds that a single possible world can provide more than one way things could be. But what are possible worlds good for if they come apart from ways things could be? We can make sense of this if we go in for a metaphysical understanding of what the world is. The world does not include everything that is the case—only the genuine facts. Understood this way, Lewis's “cheap haecceitism” amounts to a kind of metaphysical anti-haecceitism: it says there (...) aren't any genuine facts about individuals over and above their qualitative roles. (shrink)

The necessity of origin suggests that a person’s identity is determined by the particular pair of gametes from which the person originated. An implication is that speculative scenarios concerning how we might otherwise have been had our gametic origins been different are dismissed as being metaphysically impossible. Given, however, that many of these speculations are intelligible and commonplace in the discourses of competent speakers, it is overhasty to dismiss them as mistakes. This paper offers a way of understanding these speculations (...) that does not commit them to incoherence but aims to make the best sense of what they are expressing. Using the philosophical framework of two‐dimensional semantics, it proposes that the speculative scenarios are best analysed as epistemic possibilities, rather than as metaphysical possibilities. It then explores some implications of this analysis for the ethical challenges associated with the non‐identity problem. (shrink)

In this chapter, I survey what I call Lewisian approaches to modality: approaches that analyze modality in terms of concrete possible worlds and their parts. I take the following four theses to be characteristic of Lewisian approaches to modality. (1) There is no primitive modality. (2) There exists a plurality of concrete possible worlds. (3) Actuality is an indexical concept. (4) Modality de re is to be analyzed in terms of counterparts, not transworld identity. After an introductory section in which (...) I motivate analyzing modality in terms of possible worlds, I devote one section to each of these four theses. For each thesis, I take Lewis’s interpretation and defense as my starting point. I then consider and endorse alternative ways of accepting the thesis, some of which disagree substantially with Lewis’s interpretation or defense. There is more than one way to be a Lewisian about modality. (shrink)

“There are no gaps in logical space,” David Lewis writes, giving voice to sentiment shared by many philosophers. But different natural ways of trying to make this sentiment precise turn out to conflict with one another. One is a *pattern* idea: “Any pattern of instantiation is metaphysically possible.” Another is a *cut and paste* idea: “For any objects in any worlds, there exists a world that contains any number of duplicates of all of those objects.” We use resources from model (...) theory to show the inconsistency of certain packages of combinatorial principles and the consistency of others. (shrink)

This chapter discusses Kant's 1763 "possibility proof" for the existence of God. I first provide a reconstruction of the proof in its two stages, and then revisit my earlier argument according to which the being the proof delivers threatens to be a Spinozistic-panentheistic God—a being whose properties include the entire spatio-temporal universe—rather than the traditional, ontologically distinct God of biblical monotheism. I go on to evaluate some recent alternative readings that have sought to avoid this result by arguing that the (...) relevant facts about real modality can be ultimately grounded in God’s powers or thoughts – or that Kant just leaves the grounding relations mysterious. I argue that the textual and philosophical costs of each of these alternative readings are formidable. The chapter concludes with a discussion of the fate of the proof in the critical period. Some commentators think that it disappears altogether, or that it is downgraded such that it produces a mere regulative idea of God as the most real being. I suggest that the proof survives but that the mode of assent it licenses towards its conclusion changes from knowledge to a certain kind of Belief (Glaube). (shrink)

In the history of modern philosophy systematic connections were assumed to hold between the modal concepts of logical possibility and necessity and the concept of conceivability. However, in the eyes of many contemporary philosophers, insuperable objections face any attempt to analyze the modal concepts in terms of conceivability. It is important to keep in mind that a philosophical explanation of modality does not have to take the form of a reductive analysis. In this paper I attempt to provide a response-dependent (...) account of the modal concepts in terms of conceivability along the lines of a nonreductive model of explanation. (shrink)

Many epistemologists call themselves ‘fallibilists’. But many philosophers of language hold that the meaning of epistemic usages of ‘possible’ ensures a close knowledge- possibility link : a subject’s utterance of ‘it’s possible that not-p’ is true only if the subject does not know that p. This seems to suggest that whatever the core insight behind fallibilism is, it can’t be that a subject could have knowledge which is, for them, possibly false. I argue that, on the contrary, subjects can have (...) such possibly false knowledge. My ultimate aim, then, is to vindicate a very robust form of fallibilism. Uniquely, however, the account I offer does this while also allowing that concessive knowledge attributions – sentences of the form “I know that p, but it’s possible that not-p” – are not only infelicitous but actually false whenever uttered. The account predicts this result without conceding KPL. I argue that my account has the resources to explain some related cases for which the KPL account yields the wrong predictions. Taken as a whole, the linguistic data not only do not support the proposal that subjects cannot have possibly false knowledge, but indeed positively favor the proposal that they can. (shrink)

We provide a new perspective on the relation between the space of description of an object and the appearance of novelties. One of the aims of this perspective is to facilitate the interaction between mathematics and historical sciences. The definition of novelties is paradoxical: if one can define in advance the possibles, then they are not genuinely new. By analyzing the situation in set theory, we show that defining generic (i.e., shared) and specific (i.e., individual) properties of elements of a (...) set are radically different notions. As a result, generic and specific definitions of possibilities cannot be conflated. We argue that genuinely stating possibilities requires that their meaning has to be made explicit. For example, in physics, properties playing theoretical roles are generic; then, generic reasoning is sufficient to define possibilities. By contrast, in music, we argue that specific properties matter, and generic definitions become insufficient. Then, the notion of new possibilities becomes relevant and irreducible. In biology, among other examples, the generic definition of the space of DNA sequences is insufficient to state phenotypic possibilities even if we assume complete genetic determinism. The generic properties of this space are relevant for sequencing or DNA duplication, but they are inadequate to understand phenotypes. We develop a strong concept of biological novelties which justifies the notion of new possibilities and is more robust than the notion of changing description spaces. These biological novelties are not generic outcomes from an initial situation. They are specific and this specificity is associated with biological functions, that is to say, with a specific causal structure. Thus, we think that in contrast with physics, the concept of new possibilities is necessary for biology. (shrink)

The new …eld of judgment aggregation aims to …nd collective judgments on logically interconnected propositions. Recent impossibility results establish limitations on the possibility to vote independently on the propositions. I show that, fortunately, the impossibility results do not apply to a wide class of realistic agendas once propositions like “if a then b” are adequately modelled, namely as subjunctive implications rather than material implications. For these agendas, consistent and complete collective judgments can be reached through appropriate quota rules (which decide (...) propositions using acceptance thresholds). I characterise the class of these quota rules. I also prove an abstract result that characterises consistent aggregation for arbitrary agendas in a general logic. (shrink)

Typically, nudging is a technique for steering the choices of people without giving reasons or using enforcement. In benevolent cases, it is used when people are insufficiently responsive to reason. The nudger triggers automatic cognitive mechanisms – sometimes even biases – in smart ways in order to push irrational people in the right direction. Interestingly, this technique can also be applied to doxastic attitudes. Someone who is doxastically unresponsive to evidence can be nudged into forming true beliefs or doxastic attitudes (...) that are propositionally justified. When doxastic nudging uses non-rational mechanisms, the worry is that nudging cannot result in justified beliefs or knowledge, as the resulting doxastic attitudes lack the right kind of basis. In this paper, I will argue that given the right background views about knowledge, justified beliefs and the relevant processes, epistemic nudging is possible even in these cases. That is, all kinds of nudging can – in appropriate circumstances – produce justified beliefs or knowledge in the nudgee. (shrink)

What makes democracy valuable? One traditional answer holds that participating in democratic self-government amounts to a kind of autonomy: it enables citizens to be the authors of their political affairs. Many contemporary philosophers, however, are skeptical. We are autonomous, they argue, when important features of our lives are up to us, but in a democracy we merely have a say in a process of collective choice. In this paper, we defend the possibility of democratic autonomy, by advancing a conception of (...) it which is impervious to this objection. At the core of our account is the idea of joint authorship. You are a joint author of something when that thing expresses your joint intentions. Democracy may not make any one of us sole author of our political affairs, but it can make us their joint authors. It is in such joint authorship, we claim, that the intrinsic value of democratic self-government consists. (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.

A common view of how-possibly explanations in biology treats them as explanatorily incomplete. In addition to this interpretation of how-possibly explanation, I argue that there is another interpretation, one which features what I term “explanatory strategies.” This strategy-centered interpretation of how-possibly explanation centers on there being a different explanatory context within which how-possibly explanations are offered. I contend that, in conditions where this strategy context is recognized, how-possibly explanations can be understood as complete explanations. I defend this alternative interpretation by (...) analyzing the explanatory value of simple physical models the nineteenth century developmental biologist Wilhelm His constructed for animal development. (shrink)

Among the most remarkable developments in metaphysics since the 1950’s is the explosion of philosophical interest in possible worlds. This paper proposes an explanation of what possible worlds are, and argues that this proposal, the interpreted models conception, should be attractive to anyone who thinks that modal facts are primitive, and so not to be explained in terms of some non-modal notion of “possible world.” I articulate three constraints on any acceptable primitivist explanation of the nature of possible worlds, and (...) show that the interpreted models conception meets the three constraints. (shrink)

This paper argues for the existence of a fourth positive generic value relation that can hold between two items beyond ‘better than’, ‘worse than’, and ‘equally good’: namely ‘on a par’.

It is natural to assume that every value bearer must be good, bad, or neutral. This paper argues that this assumption is false if value incomparability is possible. More precisely, if value incommensurability is possible, then there is a fourth category of absolute value, in addition to the good, the bad, and the neutral.

Despite much discussion over the existence of moral facts, metaethicists have largely ignored the related question of their possibility. This paper addresses the issue from the moral error theorist’s perspective, and shows how the arguments that error theorists have produced against the existence of moral facts at this world, if sound, also show that moral facts are impossible, at least at worlds non-morally identical to our own and, on some versions of the error theory, at any world. So error theorists’ (...) arguments warrant a stronger conclusion than has previously been noticed. This may appear to make them vulnerable to counterarguments that take the possibility of moral facts as a premise. However, I show that any such arguments would be question-begging. (shrink)

This article gives two arguments for believing that our society is unknowingly guilty of serious, large-scale wrongdoing. First is an inductive argument: most other societies, in history and in the world today, have been unknowingly guilty of serious wrongdoing, so ours probably is too. Second is a disjunctive argument: there are a large number of distinct ways in which our practices could turn out to be horribly wrong, so even if no particular hypothesized moral mistake strikes us as very likely, (...) the disjunction of all such mistakes should receive significant credence. The article then discusses what our society should do in light of the likelihood that we are doing something seriously wrong: we should regard intellectual progress, of the sort that will allow us to find and correct our moral mistakes as soon as possible, as an urgent moral priority rather than as a mere luxury; and we should also consider it important to save resources and cultivate flexibility, so that when the time comes to change our policies we will be able to do so quickly and smoothly. (shrink)

We ordinarily think that we human beings have agency: we have control over our choices and make a difference to our environments. Yet it is not obvious how agency can fit into a physical world that is governed by exceptionless laws of nature. In particular, it is unclear how agency is possible if those laws are deterministic and the universe functions like a mechanical clockwork. In this short paper, I first explain the apparent conflict between agency and physical determinism (referring (...) to recent work by Helen Steward on "agency incompatibilism"), then review some salient responses one might give to this conflict, and finally sketch a response that rests on a distinction between “physical” and “agential possibilities.” Agency, I suggest, is a higher-level phenomenon, which comes with its own level-specific notion of possibility, and it cannot be adequately analyzed in physical terms alone or just through the lens of physical possibility. (The paper was written as an informal position paper for a symposium on "Possibilities".). (shrink)

The standard semantics for counterfactuals ensures that any counterfactual with a true antecedent and true consequent is itself true. There have been many recent attempts to amend the standard semantics to avoid this result. I show that these proposals invalidate a number of further principles of the standard logic of counterfactuals. The case against the automatic truth of counterfactuals with true components does not extend to these further principles, however, so it is not clear that rejecting the latter should be (...) a consequence of rejecting the former. Instead I consider how one might defuse putative counterexamples to the truth of true-true counterfactuals. (shrink)

Some defenders of the principle of alternative possibilities (PAP) have responded to the challenge of Frankfurt-style counterexamples (FSCs) to PAP by arguing that there remains a “flicker of freedom” -- that is, an alternative possibility for action -- left to the agent in FSCs. I argue that the flicker of freedom strategy is unsuccessful. The strategy requires the supposition that doing an act-on-one's-own is itself an action of sorts. I argue that either this supposition is confused and leads to (...) counter-intuitive results; or, if the supposition is acceptable, then it is possible to use it to construct a FSC in which there is no flicker of freedom at all. Either way, the flicker of freedom strategy is ineffective against FSCs. Since the flicker of freedom strategy is arguably the best defense of PAP, I conclude that FSCs are successful in showing that PAP is false. An agent can act with moral responsibility without having alternative possibilities available to her. (shrink)

The moral error theory, it seems, could be true. The mere possibility of its truth might also seem inconsequential. But it is not. For, I argue, there is a sense in which the moral error theory is possible that generates an argument against both non‐cognitivism and moral naturalism. I argue that it is an epistemic possibility that morality is subject to some form of wholesale error of the kind that would make the moral error theory true. Denying this possibility has (...) three unwelcome consequences such that allowing for and explaining it is an adequacy condition on meta‐ethical theories. Non‐cognitivism and moral naturalism, I argue, cannot capture the epistemic possibility of wholesale moral error and so are false. My argument additionally provides independent reason to accept Derek Parfit's claim that if moral non‐naturalism is false then nothing matters. I conclude that whether wholesale moral error is epistemically possible may be, in Richard Rorty's words, ‘one of those issues which puts everything up for grabs at once’ and that even if so, and even if non‐cognitivists and moral naturalists remain unmoved by an argument based upon it, this only helps to highlight the significance of my argument. (shrink)

The article investigates the sceptical challenge from an informationtheoretic perspective. Its main goal is to articulate and defend the view that either informational scepticism is radical, but then it is epistemologically innocuous because redundant; or it is moderate, but then epistemologically beneficial because useful. In order to pursue this cooptation strategy, the article is divided into seven sections. Section 1 sets up the problem. Section 2 introduces Borei numbers as a convenient way to refer uniformly to (the data that individuate) (...) different possible worlds. Section 3 adopts the Hamming distance between Borei numbers as a metric to calculate the distance between possible worlds. In Sects. 4 and 5, radical and moderate informational scepticism are analysed using Borei numbers and Hamming distances, and shown to be either harmless (extreme form) or actually fruitful (moderate form). Section 6 further clarifies the approach by replying to some potential objections. In the conclusion, the Peircean nature of the overall approach is briefly discussed. (shrink)

It's currently fashionable to take Putnamian model theoretic worries seriously for mathematics, but not for discussions of ordinary physical objects and the sciences. But I will argue that (under certain mild assumptions) merely securing determinate reference to physical possibility suffices to rule out nonstandard models of our talk of numbers. So anyone who accepts realist reference to physical possibility should not reject reference to the standard model of the natural numbers on Putnamian model theoretic grounds.

In this paper I explore the relationship between the idea of possible worlds and the notion of the beauty of God. I argue that there is a clear contradiction between the idea that God is utterly and completely beautiful on the one hand and the notion that He contains within himself all possible worlds on the other. Since some of the possible worlds residing in the mind of the deity are ugly, their presence seems to compromise God's complete and utter (...) beauty. (shrink)

In this paper, a novel experimental task is developed for testing the highly influential, but experimentally underexplored, possible worlds account of conditionals (Stalnaker, 1968; Lewis, 1973). In Experiment 1, this new task is used to test both indicative and subjunctive conditionals. For indicative conditionals, five competing truth tables are compared, including the previously untested, multi-dimensional possible worlds semantics of Bradley (2012). In Experiment 2, these results are replicated and it is shown that they cannot be accounted for by an alternative (...) hypothesis proposed by our reviewers. In Experiment 3, individual variation in truth assignments of indicative conditionals is investigated via Bayesian mixture models that classify participants as following one of several competing models. As a novelty of this study, it is found that a possible worlds semantics of Lewis and Stalnaker is capable of accounting for participants’ aggregate truth value assignments in this task. Applied to indicative conditionals, we show across three experiments, that the theory both captures participants’ truth values at the aggregate level (Experiments 1 and 2) and that it makes up the largest subgroup in the analysis of individual variation in our experimental paradigm (Experiment 3). (shrink)

In this paper, I examine the case that has been made for origin essentialism and find it wanting. I focus on the arguments of Nathan Salmon and Graeme Forbes. Like most origin essentialists, Salmon and Forbes have been concerned to respect the intuition that slight variation in the origin of an artifact or organism is possible. But, I argue, both of their arguments fail to respect this intuition. Salmon's argument depends on a sufficiency principle for cross-world identity, which should be (...) rejected, if - as Salmon concedes - a given artifact might have been originally made from slightly different material. Similarly, Forbes's argument succeeds only if essentially the same argument can be used to establish a claim that - by his own admission - is too strong, namely that no variation, however slight, in an organism's origin is possible. (shrink)

I argue that if David Lewis’ modal realism is true, modal realists from different possible worlds can fall in love with each other. I offer a method for uniquely picking out possible people who are in love with us and not with our counterparts. Impossible lovers and trans-world love letters are considered. Anticipating objections, I argue that we can stand in the right kinds of relations to merely possible people to be in love with them and that ending a trans-world (...) relationship to start a relationship with an actual person isn't cruel to one's otherworldly lover. (shrink)

A number of authors, including me, have argued that the output of our most complex climate models, that is, of global climate models and Earth system models, should be assessed possibilistically. Worries about the viability of doing so have also been expressed. I examine the assessment of the output of relatively simple climate models in the context of discovery and point out that this assessment is of epistemic possibilities. At the same time, I show that the concept of epistemic (...) possibility used in the relevant studies does not fit available analyses of this concept. Moreover, I provide an alternative analysis that does fit the studies and broad climate modelling practices as well as meshes with my existing view that climate model assessment should typically be of real possibilities. On my analysis, to assert that a proposition is epistemically possible is to assert that it is not known to be false and is consistent with at least approximate knowledge of the basic way things are. I, finally, consider some of the implications of my discussion for available possibilistic views of climate model assessment and for worries about such views. I conclude that my view helps to address worries about such assessment and permits using the full range of climate models in it. (shrink)

Realists about possible worlds typically identify possible worlds with abstract objects, such as propositions or properties. However, they face a significant objection due to Lewis (1986), to the effect that there is no way to explain how possible worlds-as-abstract objects represent possibilities. In this paper, I describe a response to this objection on behalf of realists. The response is to identify possible worlds with propositions, but to deny that propositions are abstract objects, or indeed objects at all. Instead, I (...) argue that realists should follow Prior (1971) and others in treating higher-order quantification (e.g. quantification into predicate or sentence position) as a genuine form of quantification in its own right, and so in particular, not to be analysed in terms of first-order quantification over abstract objects. I argue that from this ‘higher-orderist’ perspective, there is a relatively straightforward answer to the question of how possible worlds-as-propositions succeed in representing possibilities. (shrink)

Metaphysically possible worlds have many uses. Epistemically possible worlds promise to be similarly useful, especially in connection with propositions and propositional attitudes. However, I argue that there is a serious threat to the natural accounts of epistemically possible worlds, from a version of Russell’s paradox. I contrast this threat with David Kaplan’s problem for metaphysical possible world semantics: Kaplan’s problem can be straightforwardly rebutted, the problems I raise cannot. I argue that although there may be coherent accounts of epistemically possible (...) worlds with fruitful applications, any such an account must fundamentally compromise the basic idea behind epistemic possibility. (shrink)

Some argue that theories of universals should incorporate structural universals, in order to allow for the metaphysical possibility of worlds of 'infinite descending complexity' ('onion worlds'). I argue that the possibility of such worlds does not establish the need for structural universals. So long as we admit the metaphysical possibility of emergent universals, there is an attractive alternative description of such cases.

I use modal logic and transfinite set-theory to define metaphysical foundations for a general theory of computation. A possible universe is a certain kind of situation; a situation is a set of facts. An algorithm is a certain kind of inductively defined property. A machine is a series of situations that instantiates an algorithm in a certain way. There are finite as well as transfinite algorithms and machines of any degree of complexity (e.g., Turing and super-Turing machines and more). There (...) are physically and metaphysically possible machines. There is an iterative hierarchy of logically possible machines in the iterative hierarchy of sets. Some algorithms are such that machines that instantiate them are minds. So there is an iterative hierarchy of finitely and transfinitely complex minds. (shrink)

Kripkean examples of necessary a posteriori truths clearly provide a challenge to attempts to connect facts about possibility to facts about what people can conceive. The paper argues for a general principle connecting imaginability under certain special circumstances to possibility; it also discusses some of the issues raised by the resulting position.

In response to suspicions concerning the use of possible worlds in philosophy, this brief paper proposes an analysis of possibility that requires only a single world, using a combination of temporal logic and a potentiality operator.

The Humean view that conceivability entails possibility can be criticized via input from cognitive psychology. A mainstream view here has it that there are two candidate codings for mental representations (one of them being, according to some, reducible to the other): the linguistic and the pictorial, the difference between the two consisting in the degree of arbitrariness of the representation relation. If the conceivability of P at issue for Humeans involves the having of a linguistic mental representation, then it is (...) easy to show that we can conceive the impossible, for impossibilities can be represented by meaningful bits of language. If the conceivability of P amounts to the pictorial imaginability of a situation verifying P, then the question is whether the imagination at issue works purely qualitatively, that is, only by phenomenological resemblance with the imagined scenario. If so, the range of situations imaginable in this way is too limited to have a significant role in modal epistemology. If not, imagination will involve some arbitrary labeling component, which turns out to be sufficient for imagining the impossible. And if the relevant imagination is neither linguistic nor pictorial, Humeans will appear to resort to some representational magic, until they come up with a theory of a ‘third code’ for mental representations. (shrink)