In many diagrams one seems to perceive necessity – one sees not only that something is so, but that it must be so. That conflicts with a certain empiricism largely taken for granted in contemporary philosophy, which believes perception is not capable of such feats. The reason for this belief is often thought well-summarized in Hume's maxim: ‘there are no necessary connections between distinct existences’. It is also thought that even if there were such necessities, perception is too passive or (...) localized a faculty to register them. We defend the perception of necessity against such Humeanism, drawing on examples from mathematics. (shrink)

Modal rationalism includes the thesis that ideal primary positive conceivability entails primary possibility. Modal monism is the thesis that the space of logically possible worlds is coextensive with the space of metaphysically possible worlds. In this paper I explore the relation between the two theses. My aim is to show that the former thesis implies the latter thesis, and that problems with the latter make the former implausible as a complete picture of the epistemology of modality. My argument explores the (...) relation between logical modality and metaphysical modality. (shrink)

Bob Hale presents a broadly Fregean approach to metaphysics, according to which ontology and modality are mutually dependent upon one another. He argues that facts about what kinds of things exist depend on facts about what is possible. Modal facts are fundamental, and have their basis in the essences of things--not in meanings or concepts.

In recent work, E. J. Lowe presents an essence-based account of our knowledge of metaphysical modality that he claims to be superior to its main competitors. I argue that knowledge of essences alone, without knowledge of a suitable bridge principle, is insufficient for knowing that something is metaphysically necessary or metaphysically possible. Yet given Lowe's other theoretical commitments, he cannot account for our knowledge of the needed bridge principle, and so his essence-based modal epistemology remains incomplete. In addition to that, (...) Lowe's account implies a psychologically unrealistic reconstruction of how we ordinarily acquire knowledge of metaphysical modalities. The discussion of Lowe's suggestive essence-based account is also intended as a case study that illustrates a more general problem in the epistemology of modality: the great difficulty of explaining our modal knowledge in terms of a single overtly nonmodal kind of knowledge. The failure of Lowe's account suggests that such a sweeping reductive explanation of our modal knowledge might simply not be available. This should be good news for those philosophers who champion less reductive or more pluralistic accounts of our modal knowledge. (shrink)

In this chapter, it is suggested that our epistemic access to metaphysical modality generally involves rationalist, a priori elements. However, these a priori elements are much more subtle than ‘traditional’ modal rationalism assumes. In fact, some might even question the ‘apriority’ of these elements, but I should stress that I consider a priori and a posteriori elements especially in our modal inquiry to be so deeply intertwined that it is not easy to tell them apart. Supposed metaphysically necessary identity statements (...) involving natural kind terms are a good example: the fact that empirical input is crucial in establishing their necessity has clouded the role and content of the a priori input, as I have previously argued. For instance, the supposed metaphysically necessary identity statement involving water and its microstructure can only be established with the help of a controversial a priori principle concerning the determination of chemical properties by microstructure. The Kripke-Putnam framework of modal epistemology fails precisely because it is unclear whether the required a priori element is present. My positive proposal builds on E. J. Lowe’s work. Lowe holds that our knowledge of metaphysical modality is based on our knowledge of essence. Lowe’s account strives to offer a uniform picture of modal epistemology: essence is the basis of all our modal knowledge. This is the basis of Lowe’s modal rationalism. I believe that Lowe’s proposal is on the right lines in the case of abstract objects, but I doubt that it can be successfully applied to the case of natural kinds. Accordingly, the case of natural kinds will be my main focus and I will suggest that modal rationalism, at least as it is traditionally understood, falls short of explaining modal knowledge concerning natural kinds. Yet, I think that Lowe has identified something of crucial importance for modal epistemology, namely the essentialist, a priori elements present in our modal inquiry. The upshot is that rather than moving all the way from modal rationalism to modal empiricism, a type of hybrid approach, ‘empirically-informed modal rationalism ’, can be developed. (shrink)

Bob Hale presents a broadly Fregean approach to metaphysics, according to which ontology and modality are mutually dependent upon one another. He argues that facts about what kinds of things exist depend on facts about what is possible. Modal facts are fundamental, and have their basis in the essences of things--not in meanings or concepts.

Modality presents notorious philosophical problems, including the epistemic problem of how we could come to know modal facts and metaphysical problems about how to place modal facts in the natural world. These problems arise from thinking of modal claims as attempts to describe modal features of this world that explain what makes them true. Here I propose a different view of modal discourse in which talk about what is “metaphysically necessary” does not aim to describe modal features of the world, (...) but, rather, provides a particularly useful way of expressing constitutive semantic and conceptual rules in the object language. The result is a “modal normativist” view that enables us to avoid the epistemic problems of modality and mitigate the metaphysical worries, while also leaving open the possibility of a unified account of the function of modal language. Finally, I address a serious challenge: we have the norms we do in order to track the modal facts of the world, so that the order of explanation must go in the opposite direction. I close by showing how the normativist may answer that challenge. (shrink)

I lay out the framework for my theory of sensory imagination in “Imagining as a guide to possibility.” Sensory imagining involves mental imagery , and crucially, in describing the content of imagining, I distinguish between qualitative content and assigned content. Qualitative content derives from the mental image itself; for visual imaginings, it is what is “pictured.” For example, visually imagine the Philadelphia Eagles defeating the Pittsburgh Steelers to win their first Super Bowl. You picture the greenness of the field and (...) the football’s brown oblong shape. Some of what you imagine isn’t explicitly pictured, however. That it is Sunday, that it is the Super Bowl: these facts are assigned. (shrink)

The paper provides an explanation of our knowledge of metaphysical modality, or modal knowledge, from our ability to evaluate counterfactual conditionals. The latter ability lends itself to an evolutionary explanation since it enables us to learn from mistakes. Different logical principles linking counterfactuals to metaphysical modality can be employed to extend this explanation to the epistemology of modality. While the epistemological use of some of these principles is either philosophically implausible or empirically inadequate, the equivalence of ‘Necessarily p’ with ‘For (...) all q, if q were the case, p would be the case’ is a suitable starting-point for an explanation of modal knowledge. (shrink)

The paper compares the suitability of two different epistemologies of counterfactuals—(EC) and (W)—to elucidate modal knowledge. I argue that, while both of them explain the data on our knowledge of counterfactuals, only (W)—Williamson’s epistemology—is compatible with all counterpossibles being true. This is something on which Williamson’s counterfactual-based account of modal knowledge relies. A first problem is, therefore, that, in the absence of further, disambiguating data, Williamson’s choice of (W) is objectionably biased. A second, deeper problem is that (W) cannot satisfactorily (...) elucidate modal knowledge. Third, from a naturalistic perspective, the nature of this second problem favours (EC) against (W). (shrink)

Due to the influence of Nathan Salmon’s views, endorsement of the “flexibility of origins” thesis is often thought to carry a commitment to the denial of S4. This paper rejects the existence of this commitment and examines how Peacocke’s theory of the modal may accommodate flexibility of origins without denying S4. One of the essential features of Peacocke’s account is the identification of the Principles of Possibility, which include the Modal Extension Principle (MEP), and a set of Constitutive Principles. Regarding (...) their modal status, Peacocke argues for the necessity of MEP, but leaves open the possibility that some of the Constitutive Principles be only contingently true. Here, I show that the contingency of the Constitutive Principles is inconsistent with the recursivity of MEP, and this makes the account validate S4. It is also shown that, compatibly with the necessity of the Constitutive Principles, the account can still accommodate intuitions about flexibility of origins. However, the account we end up with once those intuitions are consistently accommodated may not be satisfactory, and this opens up the debate about whether or not artefacts allow for some variation in their origins. (shrink)

One of Hume's most well-known works and a masterpiece of philosophy, A Treatise of Human Nature is indubitably worth taking the time to read.

This monograph articulates and defends a theory-based epistemology of modality (TEM). According to TEM, someone justifiably believe an interesting modal claim if and only if (a) she justifiably believes a theory according to which that claim is true, (b) she believes that claim on the basis of that theory, and (c) she has no defeaters for her belief in that claim. The book has two parts. In the first, the author motivates TEM, sets out the view in detail, and defends (...) it against a number of objections. In the second, the author considers whether TEM is worth accepting. To argue that it is, the author sets out criteria for choosing between modal epistemologies, concluding that TEM has a number of important virtues. However, the author also concedes that TEM is cautious: it probably implies that we are not justified in believing some interesting modal claims that we might take ourselves to be justified in believing. This raises a question about TEM's relationship to Peter van Inwagen's modal skepticism, which the author explores in detail. As it turns out, TEM offers a better route to modal skepticism than the one that van Inwagen provides. But rather than being a liability, the author argues that this is a further advantage of the view. Moreover, he argues that other popular modal epistemologies do not fare better: they cannot easily secure more extensive modal justification than TEM. The book concludes by clarifying TEM’s relationship to the other modal epistemologies on offer, contending that TEM need not be a rival to those views, but can instead be a supplement to them. (shrink)

According to modalism, modality is primitive. In this paper, we examine the implications of this view for modal epistemology, and articulate a modalist account of modal knowledge. First, we discuss a theoretical utility argument used by David Lewis in support of his claim that there is a plurality of concrete worlds. We reject this argument, and show how to dispense with possible worlds altogether. We proceed to account for modal knowledge in modalist terms.

There is currently intense interest in the question of the source of our presumed knowledge of truths concerning what is, or is not, metaphysically possible or necessary. Some philosophers locate this source in our capacities to conceive or imagine various actual or non-actual states of affairs, but this approach is open to certain familiar and seemingly powerful objections. A different and ostensibly more promising approach has been developed by Timothy Williamson, according to which our capacity for modal knowledge is just (...) an extension, or by-product, of our general capacity to acquire knowledge of true counterfactual conditionals — a capacity that we deploy ubiquitously in everyday life. Williamson’s account crucially involves a thesis to the effect that modal truths can be explained in terms of counterfactual truths. In this paper, I query Williamson’s account on a number of points, including this thesis. My positive proposal, which owes a debt to the work of Kit Fine on modality and essence, appeals instead to our capacity to grasp essences, understood in a neo-Aristotelian fashion, according to which essences are expressed by ‘real definitions’. (shrink)

In recent work Timothy Williamson argues that the epistemology of metaphysical modality is a special case of the epistemology of counterfactuals. I argue that Williamson has not provided an adequate argument for this controversial claim, and that it is not obvious how what he says should be supplemented in order to derive such an argument. But I suggest that an important moral of his discussion survives this point. The moral is that experience could play an epistemic role which is more (...) epistemically significant than a mere 'enabling' role but not equivalent to an evidential role. (shrink)

There are many modal epistemologies available to us. Which should we endorse? According to Bob Hale, we can start to answer this question by examining the architecture of modal knowledge. That is, we can try to decide between the following claims: knowing that p is possible is essentially a matter of having a well-founded belief that there are no conflicting necessities—a necessity-based approach—and knowing that p is necessary is essentially a matter of having a well-founded belief that there are no (...) conflicting possibilities—a possibility-based approach. Hale argues for the first of these claims, but I contend that his arguments fail. However, it doesn't follow that we should endorse a possibility-based approach. I repurpose Hale's arguments to show those who would endorse possibility-based approaches need to say more about our modal knowledge concerning logic and mathematics; if they can't, then they ought to endorse a hybrid modal epistemology that doesn't give priority to one modality across the board. Additionally, those who endorse possibility-based views may be committed to Peter van Inwagen's modal skepticism. (shrink)

Realist essentialists face a prima facie challenge in accounting for our knowledge of the essences of things, and in particular, in justifying our engaging in thought experiments to gain such knowledge. In contrast, conferralist essentialism has an attractive story to tell about how we gain knowledge of the essences of things, and how thought experiments are a justified method for gaining such knowledge. The conferralist story is told in this essay.

Philosophical theories often hinge on claims about what is necessary or possible. But what are possibilities and necessities, and how could we come to know about them? This book aims to help demystify the methodology of philosophy, by treating such claims not as attempted descriptions of strange facts or distant 'possible worlds', but rather as ways of expressing rules or norms.

Timothy Williamson offers a reductive account of modal knowledge in terms of knowledge of counterfactual conditionals. The account is developed in a broader context of defending two more general theses regarding the subject matter and methodology of philosophy. My primary focus in this paper is Williamson’s account of modal knowledge. I argue (1) that his account of modal knowledge does not support his more general theses regarding the subject matter and methodology of philosophy; (2) that the two central claims of (...) his account of knowledge of counterfactuals are rooted in unsubstantiated empirical assumptions; and (3) that his argument in support of the conclusion that modal knowledge is a special case of counterfactual knowledge rests on three errors: conflating logical reduction and epistemological reduction, a misguided appeal to cognitive economy, and incorrectly locating what needs to be explained by an account of modal knowledge. (shrink)

Kripke claims that there are necessary a posteriori truths and contingent a priori truths. These claims challenge the traditional Kantian view that (K) All knowledge of necessary truths is a priori and all a priori knowledge is of necessary truths. Kripke’s claims continue to be resisted, which indicates that the Kantian view remains attractive. My goal is to identify the most plausible principles linking the epistemic and the modal. My strategy for identifying the principles is to investigate two related questions. (...) Are there compelling general supporting arguments for (K)? Are there decisive counterexamples to (K)? My investigation uncovers two intuitively plausible principles that are not open to decisive counterexamples but which enjoy no compelling independent support. (shrink)

Edmund Husserl has argued that we can intuit essences and, moreover, that it is possible to formulate a method for intuiting essences. Husserl calls this method 'ideation'. In this paper I bring a fresh perspective to bear on these claims by illustrating them in connection with some examples from modern pure geometry. I follow Husserl in describing geometric essences as invariants through different types of free variations and I then link this to the mapping out of geometric invariants in modern (...) mathematics. This view leads naturally to different types of spatial ontologies and it can be used to shed light on Husserl's general claim that there are different ontologies in the eidetic sciences that can be systematically related to one another. The paper is rounded out with a consideration of the role of ideation in the origins of modern geometry, and with a brief discussion of the use of ideation outside of pure geometry. (shrink)

How do we know what's (metaphysically) possible and impossible? Arguments from Kripke and Putnam suggest that possibility is not merely a matter of (coherent) conceivability/imaginability. For example, we can coherently imagine that Hesperus and Phosphorus are distinct objects even though they are not possibly distinct. Despite this apparent problem, we suggest, nevertheless, that imagination plays an important role in an adequate modal epistemology. When we discover what is possible or what is impossible, we generally exploit important connections between what is (...) possible and what we can coherently imagine. We can often come to knowledge of metaphysical modality a priori. (shrink)

David Chalmers supports his contention that there is a possible world populated by our zombie twins by arguing for the assumption that conceivability entails possibility. But, I argue, the modal epistemology he sets forth, ‘modal rationalism,’ ignores the problem of incompleteness and relies on an idealized notion of conceivability. As a consequence, this epistemology can’t justify our quotidian judgments of possibility, let alone those judgments that concern the mind/body connection. Working from the analogy that the imagination is to the possible (...) as perception is to the actual, I set forth a competing epistemology, ‘modal empiricism.’ This epistemology survives the incompleteness objection and allows some of our everyday modal judgments to be justified. But this epistemology can’t justify the claim that Zombie World is possible, which leaves Chalmers’s property dualism without the support it needs. (shrink)

According to modal empiricism, our justification for believing possibility and necessity claims is a posteriori. That is, experience does not merely play an enabling role in modal justification; it isn’t simply that experience explains how, say, we acquire the relevant concepts. Rather, the view is that modal claims answer to the tribunal of experience in roughly the way that claims about quarks and quails answer to it. One serious objection to modal empiricism is the problem of empirical conservativeness: it doesn’t (...) seem that experience can distinguish between modal claims. And if experience can’t manage that, it’s hard to see how it can provide evidence for one claim over the other. So if modal empiricism is true, we ought to be modal skeptics. On the assumption that we shouldn’t be modal skeptics, we should reject modal empiricism. I have two aims here: first, to reply to this objection to modal empiricism; second, to sketch a modal epistemology that fits with the reply I offer. (shrink)