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)

The term ‘naturalism’ has no very precise meaning in contemporary philosophy. Its current usage derives from debates in America in the first half of the last century. The self-proclaimed ‘naturalists’ from that period included John Dewey, Ernest Nagel, Sidney Hook and Roy Wood Sellars. These philosophers aimed to ally philosophy more closely with science. They urged that reality is exhausted by nature, containing nothing ‘supernatural’, and that the scientific method should be used to investigate all areas of reality, including the (...) ‘human spirit’ (Krikorian 1944, Kim 2003). (shrink)

I propose that we approach the epistemology of modality by putting modal metaphysics first and, specifically, by investigating the metaphysics of essence. Following a prominent Neo-Aristotelian view, I hold that metaphysical necessity depends on the nature of things, namely their essences. I further clarify that essences are core properties having distinctive superexplanatory powers. In the case of natural kinds, which is my focus in the paper, superexplanatoriness is due to the fact that the essence of a kind is what causes (...) all the many properties and behaviors that are typically shared by all the instances of the kind. Accordingly, we know what is necessarily true of kinds by knowing what is essential to them in the sense of actually playing such causal-explanatory roles. Modal reasoning aimed at discovering metaphysical necessity thus proceeds via essentialist deduction: we move from essentialist truths to reach necessary truths. (shrink)

Although traditionally neglected, mathematical diagrams have recently begun to attract attention from philosophers of mathematics. By now, the literature includes several case studies investigating the role of diagrams both in discovery and justification. Certain preliminary questions have, however, been mostly bypassed. What are diagrams exactly? Are there different types of diagrams? In the scholarly literature, the term “mathematical diagram” is used in diverse ways. I propose a working definition that carves out the phenomena that are of most importance for a (...) taxonomy of diagrams in the context of a practice-based philosophy of mathematics, privileging examples from contemporary mathematics. In doing so, I move away from vague, ordinary notions. I define mathematical diagrams as forming notational systems and as being geometric/topological representations or two-dimensional representations. I also examine the relationship between mathematical diagrams and spatiotemporal intuition. By proposing an explication of diagrams, I explain certain controversies in the existing literature. Moreover, I shed light on why mathematical diagrams are so effective in certain instances, and, at other times, dangerously misleading. (shrink)

I discuss several problems for Williamson’s counterfactual-theory of modal knowledge and argue that they have a common source, in that the theory neglects to elucidate the proper constraints on modal reasoning. Williamson puts forward an empirical hypothesis that rests on the role of counterfactual reasoning for modal knowledge. But he overlooks central questions of normative modal epistemology. In order for counterfactual reasoning to yield correct beliefs about modality, it needs to be suitably constrained. I argue that what is needed is, (...) specifically, information concerning the nature or essence of things. By integrating this information, essentialist deduction arguably provides a better account of our knowledge of modality. Furthermore, I argue that essences have distinctive causal and explanatory powers—indeed, essences are superexplanatory for how things are. Compared to Williamson’s counterfactual-theory, superexplanatory essentialism clarifies what the proper constraints on modal reasoning are, and why they have such a special status. (shrink)

Is imagination a source of knowledge? Timothy Williamson has recently argued that our imaginative capacities can yield knowledge of a variety of matters, spanning from everyday practical matters to logic and set theory. Furthermore, imagination for Williamson plays a similar epistemic role in cognitive processes that we would traditionally classify as either a priori or a posteriori, which he takes to indicate that the distinction itself is shallow and epistemologically fruitless. In this chapter, I aim to defend the a priori-a (...) posteriori distinction from Williamson’s challenge by questioning his account of imagination. I distinguish two notions of imagination at play in Williamson’s account – sensory vs. belief-like imagination – and show that both face empirical and normative issues. Sensory imagination seems neither necessary nor sufficient for knowledge. Whereas, belief-like imagination isn’t adequately disentangled from inference. Additionally, Williamson’s examples are ad hoc and don’t generalize. I conclude that Williamson’s case against the a priori-a posteriori distinction is unconvincing, and so is the thesis that imagination is an epistemic source. (shrink)

This is the most comprehensive book ever published on philosophical methodology. A team of thirty-eight of the world's leading philosophers present original essays on various aspects of how philosophy should be and is done. The first part is devoted to broad traditions and approaches to philosophical methodology. The entries in the second part address topics in philosophical methodology, such as intuitions, conceptual analysis, and transcendental arguments. The third part of the book is devoted to essays about the interconnections between philosophy (...) and neighbouring fields, including those of mathematics, psychology, literature and film, and neuroscience. (shrink)

The distinction between the a priori and the a posteriori is an old and influential one. But both the distinction itself and the crucial notion of a priori knowledge face powerful philosophical challenges. Many philosophers worry that accepting the a priori is tantamount to accepting epistemic magic. In contrast, this Element argues that the a priori can be formulated clearly, made respectable, and used to do important epistemological work. The author's conception of the a priori and its role falls short (...) of what some historical proponents of the notion may have hoped for, but it allows us to accept and use the notion without abandoning either naturalism or empiricism, broadly understood. This Element argues that we can accept and use the a priori without magic. (shrink)

We seem to be able to acquire evaluative knowledge by mere reflection, or “from the armchair.” But how? This question is especially pressing for proponents of sentimental perceptualism, which is the view that our evaluative knowledge is rooted in affective experiences in much the way that everyday empirical knowledge is rooted in perception. While such empirical knowledge seems partially explained by causal relations between perceptions and properties in the world, in armchair evaluative inquiry, the relevant evaluative properties are typically not (...) even present. The paper shows how sentimental perceptualists can ultimately provide a broadly causal explanation of our reflective evaluative knowledge. (shrink)

The fourteen papers in this collection offer a variety of original contributions to the epistemology of modality. In seeking to explain how we might account for our knowledge of possibility and necessity, they raise some novel questions, develop some unfamiliar theoretical perspectives, and make some intriguing proposals. Collectively, they advance our understanding of the field. In Part I of this Introduction, I give some general background about the contemporary literature in the area, by sketching a timeline of the main tendencies (...) of the past twenty-five years or so, up to the present debates. Next, I focus on four features that largely characterize the latest literature, and the papers in the present collection in particular: (i) an endorsement of the importance of essentialism; (ii) a shift to a “metaphysics-first” approach to modal epistemology; (iii) a focus on metaphysical modality as opposed to other kinds of modality; and (iv) a preference for non-uniform modal epistemology. In Part II, I present the individual papers in the volume. These are organized around the following four chapters, based on their topic: (A) Skepticism & Deflationism; (B) Essentialism; (C) Non-Essentialist Accounts; (D) Applications. -/- LIST OF CONTRIBUTORS: Francesco Berto; Stephen Biggs & Jessica Wilson; Justin Clark-Doane; Philip Goff; Bob Hale; Frank Jackson; Mark Jago; Boris Kment; Antonella Mallozzi; Graham Priest; Gabriel Rabin; Amie Thomasson; Anand Vaidya & Michael Wallner; Jennifer Wang. -/- The volume is dedicated to the memory of Bob Hale. -/- . (shrink)

Two-dimensional (2D) semantics is a formal framework that is used to characterize the meaning of certain linguistic expressions and the entailment relations among sentences containing them. 2D semantics has also been applied to thought contents. In contrast with standard possible worlds semantics, 2D semantics assigns extensions and truth-values to expressions relative to two possible world parameters, rather than just one. So a 2D semantic framework provides finer-grained semantic values than those available within standard possible world semantics, while using the same (...) basic model-theoretic resources. The 2D framework itself is just a formal tool. To develop a semantic theory for someone’s language, a proponent of 2D semantics must do three things: (i) explain what exactly the two possible world parameters represent, (ii) explain the rules for assigning 2D semantic values to a person’s words and sentences, and (iii) explain how 2D semantic values help in understanding the meanings of the person’s words and sentences. (shrink)

Thought experiments invite us to evaluate philosophical theses by making judgements about hypothetical cases. When the judgements and the theses conflict, it is often the latter that are rejected. But what is the nature of the judgements such that they are able to play this role? I answer this question by arguing that typical judgements about thought experiments are in fact judgements of normal counterfactual sufficiency. I begin by focusing on Anna-Sara Malmgren’s defence of the claim that typical judgements about (...) thought experiments are mere possibility judgements. This view is shown to fail for two closely related reasons: it cannot account for the incorrectness of certain misjudgements, and it cannot account for the inconsistency of certain pairs of conflicting judgements. This prompts a reconsideration of Timothy Williamson’s alternative proposal, according to which typical judgements about thought experiments are counterfactual in nature. I show that taking such judgements to concern what would normally hold in instances of the relevant hypothetical scenarios avoids the objections that have been pressed against this kind of view. I then consider some other potential objections, but argue that they provide no grounds for doubt. (shrink)

In this paper, I focus on the Armchair Access Problem for E=K as presented by Nicholas Silins (2005), and I argue, contra Silins, that it does not represent a real threat to E=K. More precisely, I put forward two lines of response, both of which put pressure on the main assumption of the argument, namely, the Armchair Access thesis. The first line of response focuses on its scope, while the second line of response focuses on its nature. The second line (...) of response is the most interesting one, for it represents the framework within which I develop a novel account of second-order knowledge, one that involves evaluation of counterfactual conditionals and the employment of our imaginative capacities, i.e., an imagination-based account of second-order knowledge. The two lines of response are shown to be jointly compatible and mutually supportive. I then conclude that the Armchair Access Problem is not a challenge for E=K, yet it relies on the ambiguity of the notion of armchair knowledge underpinning the Armchair Access thesis. (shrink)

This article discusses the role of a priori and a posteriori knowledge and methods in metaphysics and metametaphysics. Issues discussed include the viability of the distinction, the continuity of a priori and a posteriori methods, connections to modal epistemology, and the role of the distinction for science and naturalistic metaphysics.

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. (shrink)

During the past decade a new twist in the debate regarding the a priori has unfolded. A number of prominent epistemologists have challenged the coherence or importance of the a priori—a posteriori distinction or, alternatively, of the concept of a priori knowledge. My focus in this paper is on these new challenges to the a priori. My goals are to provide a framework for organizing the challenges, articulate and assess a range of the challenges, and present two challenges of my (...) own. (shrink)

Agents can think using concepts they do not fully understand. This paper investigates the question “Under what conditions does a thinker fully understand, or have mastery of, a concept?” I lay out a gauntlet of problems and desiderata with which any theory of concept mastery must cope. I use these considerations to argue against three views of concept mastery, according to which mastery is a matter of holding certain beliefs, being disposed to make certain inferences, or having certain intuitions. None (...) of these attitudes is either necessary or sufficient for mastery. I propose and respond to objections to my own recognition view of the conditions under which a thinker has mastery of a concept. (shrink)

This book concerns the foundations of epistemic modality and hyperintensionality and their applications to the philosophy of mathematics. David Elohim examines the nature of epistemic modality, when the modal operator is interpreted as concerning both apriority and conceivability, as well as states of knowledge and belief. The book demonstrates how epistemic modality and hyperintensionality relate to the computational theory of mind; metaphysical modality and hyperintensionality; the types of mathematical modality and hyperintensionality; to the epistemic status of large cardinal axioms, undecidable (...) propositions, and abstraction principles in the philosophy of mathematics; to the modal and hyperintensional profiles of the logic of rational intuition; and to the types of intention, when the latter is interpreted as a hyperintensional mental state. Chapter \textbf{2} argues for a novel type of expressivism based on the duality between the categories of coalgebras and algebras, and argues that the duality permits of the reconciliation between modal and hyperintensional cognitivism and modal and hyperintensional expressivism. Elohim develops a novel, topic-sensitive truthmaker semantics for dynamic epistemic logic, and develops a novel, dynamic two-dimensional semantics grounded in two-dimensional hyperintensional Turing machines. Chapter \textbf{3} provides an abstraction principle for two-dimensional (hyper-)intensions. Chapter \textbf{4} advances a topic-sensitive two-dimensional truthmaker semantics, and provides three novel interpretations of the framework along with the epistemic and metasemantic. Chapter \textbf{5} applies the fixed points of the modal $\mu$-calculus in order to account for the iteration of epistemic states in a single agent, by contrast to availing of modal axiom 4 (i.e. the KK principle). The fixed point operators in the modal $\mu$-calculus are rendered hyperintensional, which yields the first hyperintensional construal of the modal $\mu$-calculus in the literature and the first application of the calculus to the iteration of epistemic states in a single agent instead of the common knowledge of a group of agents. Chapter \textbf{6} advances a solution to the Julius Caesar problem based on Fine's `criterial' identity conditions which incorporate conditions on essentiality and grounding. Chapter \textbf{7} provides a ground-theoretic regimentation of the proposals in the metaphysics of consciousness and examines its bearing on the two-dimensional conceivability argument against physicalism. The topic-sensitive epistemic two-dimensional truthmaker semantics developed in chapters \textbf{2} and \textbf{4} is availed of in order for epistemic states to be a guide to metaphysical states in the hyperintensional setting. -/- Chapters \textbf{8-12} provide cases demonstrating how the two-dimensional hyperintensions of hyperintensional, i.e. topic-sensitive epistemic two-dimensional truthmaker, semantics, solve the access problem in the epistemology of mathematics. Chapter \textbf{8} examines the interaction between Elohim's hyperintensional semantics and the axioms of epistemic set theory, large cardinal axioms, the Epistemic Church-Turing Thesis, the modal axioms governing the modal profile of $\Omega$-logic, Orey sentences such as the Generalized Continuum Hypothesis, and absolute decidability. These results yield inter alia the first hyperintensional Epistemic Church-Turing Thesis and hyperintensional epistemic set theories in the literature. Chapter \textbf{9} examines the modal and hyperintensional commitments of abstractionism, in particular necessitism, and epistemic hyperintensionality, epistemic utility theory, and the epistemology of abstraction. Elohim countenances a hyperintensional semantics for novel epistemic abstractionist modalities. Elohim suggests, too, that higher observational type theory can be applied to first-order abstraction principles in order to make first-order abstraction principles recursively enumerable, i.e. Turing machine computable, and that the truth of the first-order abstraction principle for two-dimensional hyperintensions is grounded in its being possibly recursively enumerable and the machine being physically implementable. Chapter \textbf{10} examines the philosophical significance of hyperintensional $\Omega$-logic in set theory and discusses the hyperintensionality of metamathematics. Chapter \textbf{11} provides a modal logic for rational intuition and provides a hyperintensional semantics. Chapter \textbf{12} avails of modal coalgebras to interpret the defining properties of indefinite extensibility, and avails of hyperintensional epistemic two-dimensional semantics in order to account for the interaction between interpretational and objective modalities and the truthmakers thereof. This yields the first hyperintensional category theory in the literature. Elohim invents a new mathematical trick in which first-order structures are treated as categories, and Vopenka's principle can be satisfied because of the elementary embeddings between the categories and generate Vopenka cardinals in the category of Set in category theory. Chapter \textbf{13} examines modal responses to the alethic paradoxes. Elohim provides a counter-example to epistemic closure for logical deduction. Chapter \textbf{14} examines, finally, the modal and hyperintensional semantics for the different types of intention and the relation of the latter to evidential decision theory. (shrink)

Many versions of the ontological argument have two shortcomings: First, despite the arguments put forward, for example, by Hugh Chandler and Nathan Salmon, they assume that S5 is the correct modal logic for metaphysical modality. Second, despite the classical arguments put forward, for example, by David Hume and Immanuel Kant or the more recent arguments put forward, for example, by John Findlay and Richard Swinburne, they assume that necessary existence is possible. The aim of the paper is to develop an (...) alternative version of the ontological argument that, by an appeal to the logic of ‘actually’, avoids these two shortcomings. The version helps to leave aside unnecessary debates about the modal logic S5 or about the possibility of necessary existence and to focus on the actual challenge for the debate about the ontological argument: the challenge to evaluate the claim that it is possible that God exists. (shrink)

Can we acquire apriori knowledge of mathematical facts from the outputs of computer programs? People like Burge have argued (correctly in our opinion) that, for example, Appel and Haken acquired apriori knowledge of the Four Color Theorem from their computer program insofar as their program simply automated human forms of mathematical reasoning. However, unlike such programs, we argue that the opacity of modern LLMs and DNNs creates obstacles in obtaining apriori mathematical knowledge from them in similar ways. We claim though (...) that if a proof-checker automating human forms of proof-checking is attached to such machines, then we can obtain apriori mathematical knowledge from them after all, even though the original machines are entirely opaque to us and the proofs they output may not, themselves, be human-surveyable. (shrink)

Recently, philosophers have put forth views in the epistemology of disagreement that emphasize the epistemic relevance of the first-person perspective in disa- greement. In the first part of the paper, I attempt a rational reconstruction of these views. I construe these views as invoking the first-person perspective to explain why it is rational for parties to a disagreement to privilege their own opinions in the absence of independent explanations for doing so—to privilege without independent explanations. I reconstruct three ways privilege (...) might be thought to arise: by demotion, through self-trust, and through the epistemic immediacy in the first-person perspective. I argue that none of these ways, and none of the views that make use of them, clarify a compelling account of the epistemic relevance of the first-person perspective. In the second part of the paper, I try to discern some lessons and outline an alternative approach. According to this approach, the epistemic relevance of the first-person perspective is not to explain privilege without independent explanations but to explain the epistemic limits of intersubjective understanding. These limits are manifest in reflective disagreement and explain how other minds matter for one’s own mind in the pursuit of knowledge. The resulting view about the epistemology of disagreement is neither skeptical nor dogmatic, but dialectical, involving an active mental state that conceptualizes not only the subject matter but also one’s own and others’ minds in thinking and rational interaction at the epistemic limits of intersubjective understanding. (shrink)

In this paper, we explore the traditional conception of a prioricity as epistemic independence of evidence from sense experience. We investigate the fortunes of the traditional conception in the light of recent challenges by Timothy Williamson. We contend that Williamson’s arguments can be resisted in various ways. En route, we argue that Williamson’s views are not as distant from tradition as they might seem at first glance.

Contemporary epistemologists typically define a priori justification as justification that is independent of sense experience. However, sense experience plays at least some role in the production of many paradigm cases of a priori justified belief. This raises the question of when experience is epistemically relevant to the justificatory status of the belief that is based on it. In this paper, I will outline the answers that can be given by the two currently dominant accounts of justification, i.e. evidentialism and reliabilism. (...) While for the evidentialist, experience is epistemically relevant only if it is used as evidence, the reliabilist requires that the reliability of the relevant process depends on the reliability of experiential processes. I will argue that the reliabilist account accommodates our pre-theoretic classifications much better. In the final part of my paper I will use the reliabilist criterion to defend the a priori—a posteriori distinction against recent challenges by Hawthorne and Williamson. (shrink)

Philosophy and Phenomenological Research, EarlyView.

Although thought experiments were first discovered as a sui generis methodological tool by philosophers of science (most prominently by Ernst Mach), the tool can also be found – even more frequently – in contemporary philosophy. Thought experiments in philosophy and science have a lot in common. However, in this chapter we will concentrate on thought experiments in philosophy only. Their use has been the centre of attention of metaphilosophical discussion in the past decade, and this chapter will provide an overview (...) of the results this discussion has achieved and point out which issues are still open. (shrink)

Williamson and others have recently argued against the significance of the a priori/a posteriori distinction. My aim in this paper is to explain, defend, and expand upon one of these arguments. In the first section, I develop in some detail a line of argument sketched in Williamson. In the second section, I consider two replies to Williamson and show that they miss the structure of the challenge, as I understand it. The problem for defenders of the distinction is to find (...) a way to draw it without leaving out some paradigmatic a priori knowledge or including some paradigmatic a posteriori knowledge. Interestingly, the two replies fail in opposite directions. I then consider the view that, in cases of a priori knowledge, one needs only understanding and some reasoning to gain justified belief. Such reasoning, I argue, should itself not be dependent on experience. Next, I consider, and reject, the attempt to spell out independence of experience for reasoning based on a link between the modal and epistemic status of the proposition involved. Finally, I provide some general grounds to think that the role of experience in forming a reasoning competence, while not evidential, is not devoid of normative value. The main reason is that the normative status of intellectual competences depends on the experiences that constitute their acquisition and development. (shrink)

In recent years, several philosophers have argued that the a priori/a posteriori distinction is a legitimate distinction but does not carve at the epistemological joints and is theoretically unimportant. In this paper, I do two main things. First, I respond to the most prominent recent challenge to the significance of the a priori/a posteriori distinction – the central argument in Williamson (2013). Second, I discuss the question of what the theoretical significance of the a priori/a posteriori distinction is. -/- I (...) first present the a priori/a posteriori distinction as it is typically developed. I then turn to Williamson’s challenge to the significance of the distinction. Williamson points out that we often use the same cognitive mechanisms in coming to have a priori and a posteriori knowledge. So how could it be, asks Williamson, that there is a “deep epistemological difference” between the two? In response to this challenge, I argue that there is an important disanalogy between Williamson’s central example of a case of a priori knowledge and his central example of a case of a posteriori knowledge. Although the beliefs in the two cases are formed in similar ways, the ways in which their justification can be defeated are different. This suggests that there is an important epistemological difference between the two cases, one that cannot be captured in terms of the cognitive mechanisms used to form the beliefs. -/- Although Williamson’s argument is unsuccessful, there remains the question of just what the theoretical significance of the a priori/a posteriori distinction is. I argue that the point of the distinction is not to enable us to represent some joint in nature, but rather to help us to identify epistemological problem cases. We understand – more-or-less – the epistemology of simple perceptual knowledge. The epistemology of non-perceptual knowledge is far less clear. The purpose of labeling a case of knowledge as a priori is to claim that its epistemology should not be assimilated to the epistemology of perception. Instead, it is something of a puzzle case. -/- This proposal has an important implication. There are several ways in which a case of knowledge can be different from a simple case of perceptual knowledge. Two differences are perhaps the most important: (i) the justification of the belief does not involve phenomenality, and (ii) the belief does not stand in a causal relation to what the belief is about. When beliefs about some subject matter fit either (i) or (ii), an epistemological puzzle arises. So there is more than one kind of epistemological puzzle to solve. This suggests that there is an important theoretical role for (at least) two distinctions in the ballpark of the traditional a priori/a posteriori distinction. (shrink)

Agustín Rayo’s The Construction of Logical Space offers an exciting and ambitious defense of a broadly Carnapian approach to metaphysics. This essay will focus on one of the main differences between Rayo’s and Carnap’s approaches. Carnap distinguished between analytic, a priori “meaning postulates”, and empirical claims, which were both synthetic and knowable only a posteriori. Like meaning postulates, they determine the boundaries of logical space. But Rayo is skeptical that the a priori/a posteriori or analytic/synthetic distinctions can do the work (...) Carnap wanted them to, so unlike meaning postulates, ‘just is’-statements aren’t assumed to be analytic or knowable a priori. This essay will concern the epistemology of ‘just is’-statements in Rayo’s picture. If not by a priori reflection, how can we determine which ones to accept? I’ll distinguish two competing strands in Rayo’s work. The less radical, Lewisian strand holds that the question of whether to accept a ‘just is’-statement can be addressed in a neutral, non-question-begging way, by a kind of cost-benefit analysis. The more radical, Kuhnian strand holds that there can be no ‘just is’-statement-independent, rational choice of which ‘just is’-statements to accept. I argue that Rayo faces strong internal pressure to adopt the Kuhnian picture. While it is possible for Rayo to resist these Kuhnian pressures, natural strategies for doing so leave his view more similar to Carnap’s than the above gloss suggested. (shrink)

This paper argues that every inductive inference is covertly deductive and that validity might involve different kinds of necessity (logical, nomological, metaphysical). The main distinction is between inductivism, the view that some inferences are genuinely inductive, and deductivism, the notion that all inductive inferences are covertly deductive. Section 2 presents the problems of inductivism, highlighting its conceptual deficiencies and advancing deductivism as an alternative. In section 3, I argue that the epistemic commitments of inductivism and deductivism presuppose fallibilism and infallibilism, (...) respectively. Section 4 attempts to clarify the metaphysical assumptions of both positions and suggest a modal interpretation of probability that illuminates some puzzles regarding chancy counterfactuals. Section 5 concludes. (shrink)

The debate around the notions of a priori knowledge and a posteriori knowledge has proven crucial for the development of many fields in philosophy, such as metaphysics, epistemology, metametaphysics etc. We advocate that the recent debate on the two notions is also fruitful for man-made distributed computing systems and for the epistemic analysis thereof. Following a recently proposed modal and fallibilistic account of a priori knowledge, we elaborate the corresponding concept of a priori belief: We propose a rich taxonomy of (...) types of a priori beliefs and their role for the different agents that participate in the system engineering process, which match the existing view exceedingly well and are particularly promising for explaining and dealing with unexpected behaviors in fault-tolerant distributed systems. Developing such a philosophical foundation will provide a sound basis for eventually implementing our ideas in a suitable epistemic reasoning and analysis framework and, hence, constitutes a mandatory first step for developing methods and tools to cope with the various challenges that emerge in such systems. (shrink)

Much of contemporary metaethics revolves around the issue of “naturalism.” However, there is little agreement on what “naturalism” is or why it should be of significance. In this paper, I aim to rectify this situation by providing a set of necessary conditions on what positions ought to count as “naturalistic.” A metaethical view should count as an instance of naturalism only if it claims that there can be evidence for normative claims that is both public and spatiotemporal. I argue that, (...) unlike other characterizations of “naturalism,” this view shows a clear difference between many metaethical positions and the sciences. The view thereby renders debates about naturalism philosophically significant: the division between naturalists and non‐naturalists is that between philosophers who hold that ethics is relevantly similar to the sciences and those who deny this. (shrink)

O objectivo deste artigo consiste em introduzir a noção de conhecimento a priori e os problemas que a envolvem. Começa-se por caracterizar o conhecimento a priori e aquilo que o distingue do conhecimento a posteriori para de seguida avaliar-se as dificuldades que uma compreensão adequada da noção de independência da experiência enfrenta. A noção de a priori é distinguida da de necessidade, à qual, tradicionalmente, tem sido associada. Por fim, o problema do a priori é formulado e as principais teorias (...) que a ele respondem brevemente discutidas. (shrink)

What is the role of imagination in a priori knowledge? Here I provide a partial answer, arguing that imagination can be used to shed light on which experiences merely enable knowledge, versus which are evidential. I reach this partial answer by considering in detail Timothy’s Williamson’s recent argument that the a priori/a posteriori distinction is insignificant. There are replies to the argument by Boghossian and Casullo that might work on their own terms, but my reply examines the assumptions that Williamson (...) makes about the role of imagination in knowledge generation. I show that Williamson’s argument does not account for important distinctions from recent discussions of imaginative content. When these distinctions are not ignored, we can see that Williamson’s argument attributes a subject knowledge on the basis of a faulty application of universal generalization. I close by connecting my positive account of the role of imagination in the a priori to a debate about the role of memory in the a priori that played out 25 years ago. (shrink)

Gettier’s paper, “Is Justified True Belief Knowledge?,” is widely taken to be a paradigm example of the sort of philosophical methodology that has been so hotly debated in the recent literature. Reflection on it motivates the following four theses about that methodology: (A) Intuitive judgments form an epistemically distinctive kind. (B) Intuitive judgments play an epistemically privileged role in philosophical methodology. (C) If intuitive judgments play an epistemically privileged role in philosophical methodology, then their role is to be taken as (...) given inputs into generally accepted forms of reasoning. (D) Philosophical methodology is reasonable. Negative experimental philosophers have empirically challenged (D). Radical responses to their challenge include Williamson’s rejection of (A) and Cappelen and Deutsch’s rejection of (B). Here I follow traditionalists in maintaining (A), (B), and (D), but suggest questioning (C), which has largely been taken as a fixed point in the literature. (shrink)

This book is about the idea that some true statements would have been true no matter how the world had turned out, while others could have been false. It develops and defends a version of the idea that we tell the difference between these two types of truths in part by reflecting on the meanings of words. It has often been thought that modal issues—issues about possibility and necessity—are related to issues about meaning. In this book, the author defends the (...) view that the analysis of meaning is not just a preliminary to answering modal questions in philosophy; it is not merely that before we can find out whether something is possible, we need to get clear on what we are talking about. Rather, clarity about meaning often brings with it answers to modal questions. In service of this view, the author analyzes the notion of necessity and develops ideas about linguistic meaning, applying them to several puzzles and problems in philosophy of language. Meaning and Metaphysical Necessity will be of interest to scholars and advanced students working in metaphysics, philosophy of language, and philosophical logic. [See my homepage for a sample chapter.]. (shrink)

Interview with professor Robert D Rupert.

In this paper, I defend the view that any good account of the logical form of thought experiments should contain a conditional. Moreover, there are some reasons to think it should be a counterfactual conditional. First, I defend Williamson’s account of the logical form of thought experiments against a competing account offered by Ichikawa and Jarvis. The two accounts have a similar structure, but Williamson’s posits a counterfactual conditional where Ichikawa and Jarvis’ posits a strict conditional. Williamson’s motivation is related (...) to the problem of deviant realizations, and Ichikawa and Jarvis propose to take care of this problem by enriching the content of the thought experiment in the way we enrich the content of a text of fiction. However, this sort of enrichment is also compatible with Williamson’s account. I then consider a different view, defended by Malmgren, on which a complex possibility claim exhausts our reasoning on typical thought experiments. I argue that this account, leaving out a conditional, fails to represent an important part of our reasoning with thought experiments. This is brought out by reflection on the relationship between thought experiments and similar actual cases and by reflection on the requirement, formulated by Malmgren herself, that our reasoning should have an adequate level of generality. (shrink)

The view that contradictions cannot be true has been part of accepted philosophical theory since at least the time of Aristotle. In this regard, it is almost unique in the history of philosophy. Only in the last forty years has the view been systematically challenged with the advent of dialetheism. Since Graham Priest introduced dialetheism as a solution to certain self-referential paradoxes, the possibility of true contradictions has been a live issue in the philosophy of logic. Yet, despite the arguments (...) advanced by dialetheists, many logicians and philosophers still hold the opinion that contradictions cannot be true. -/- Rather than advocating the truth of certain contradictions, this thesis offers a different challenge to the classical logician. By showing that it can be philosophically coherent to propose that true contradictions are metaphysically possible, the thesis suggests that the classical logician must do more than she currently has to justify her confidence in the impossibility of true contradictions. Simply fighting off the dialetheist’s putative examples of true contradictions at the actual world isn’t enough to justify the classical logician’s conclusion that true contradictions are impossible. -/- To aid the thesis dialectically, we introduce a new position, absolutism, which hypothesises that it’s metaphysically possible for at least one contradiction to be true, contrasting with the dialetheic hypothesis that some contradictions are true in the actual world. We demonstrate that absolutism can be given a philosophically coherent interpretation, an appropriate logic, and that certain criticisms are completely toothless against absolutism. The challenge put to the classical logician is then: On what logical or philosophical grounds can we rule out the metaphysical possibility of true contradictions? (shrink)

This book concerns the foundations of epistemic modality and hyperintensionality and their applications to the philosophy of mathematics. David Elohim examines the nature of epistemic modality, when the modal operator is interpreted as concerning both apriority and conceivability, as well as states of knowledge and belief. The book demonstrates how epistemic modality and hyperintensionality relate to the computational theory of mind; metaphysical modality and hyperintensionality; the types of mathematical modality and hyperintensionality; to the epistemic status of large cardinal axioms, undecidable (...) propositions, and abstraction principles in the philosophy of mathematics; to the modal and hyperintensional profiles of the logic of rational intuition; and to the types of intention, when the latter is interpreted as a hyperintensional mental state. Chapter \textbf{2} argues for a novel type of expressivism based on the duality between the categories of coalgebras and algebras, and argues that the duality permits of the reconciliation between modal and hyperintensional cognitivism and modal and hyperintensional expressivism. Elohim develops a novel, topic-sensitive truthmaker semantics for dynamic epistemic logic, and develops a novel, dynamic two-dimensional semantics grounded in two-dimensional hyperintensional Turing machines. Chapter \textbf{3} provides an abstraction principle for two-dimensional (hyper-)intensions. Chapter \textbf{4} advances a topic-sensitive two-dimensional truthmaker semantics, and provides three novel interpretations of the framework along with the epistemic and metasemantic. Chapter \textbf{5} applies the fixed points of the modal $\mu$-calculus in order to account for the iteration of epistemic states in a single agent, by contrast to availing of modal axiom 4 (i.e. the KK principle). The fixed point operators in the modal $\mu$-calculus are rendered hyperintensional, which yields the first hyperintensional construal of the modal $\mu$-calculus in the literature and the first application of the calculus to the iteration of epistemic states in a single agent instead of the common knowledge of a group of agents. Chapter \textbf{6} advances a solution to the Julius Caesar problem based on Fine's `criterial' identity conditions which incorporate conditions on essentiality and grounding. Chapter \textbf{7} provides a ground-theoretic regimentation of the proposals in the metaphysics of consciousness and examines its bearing on the two-dimensional conceivability argument against physicalism. The topic-sensitive epistemic two-dimensional truthmaker semantics developed in chapters \textbf{2} and \textbf{4} is availed of in order for epistemic states to be a guide to metaphysical states in the hyperintensional setting. -/- Chapters \textbf{8-12} provide cases demonstrating how the two-dimensional hyperintensions of hyperintensional, i.e. topic-sensitive epistemic two-dimensional truthmaker, semantics, solve the access problem in the epistemology of mathematics. Chapter \textbf{8} examines the interaction between Elohim's hyperintensional semantics and the axioms of epistemic set theory, large cardinal axioms, the Epistemic Church-Turing Thesis, the modal axioms governing the modal profile of $\Omega$-logic, Orey sentences such as the Generalized Continuum Hypothesis, and absolute decidability. These results yield inter alia the first hyperintensional Epistemic Church-Turing Thesis and hyperintensional epistemic set theories in the literature. Chapter \textbf{9} examines the modal and hyperintensional commitments of abstractionism, in particular necessitism, and epistemic hyperintensionality, epistemic utility theory, and the epistemology of abstraction. Elohim countenances a hyperintensional semantics for novel epistemic abstractionist modalities. Elohim suggests, too, that higher observational type theory can be applied to first-order abstraction principles in order to make first-order abstraction principles recursively enumerable, i.e. Turing machine computable, and that the truth of the first-order abstraction principle for two-dimensional hyperintensions is grounded in its being possibly recursively enumerable and the machine being physically implementable. Chapter \textbf{10} examines the philosophical significance of hyperintensional $\Omega$-logic in set theory and discusses the hyperintensionality of metamathematics. Chapter \textbf{11} provides a modal logic for rational intuition and provides a hyperintensional semantics. Chapter \textbf{12} avails of modal coalgebras to interpret the defining properties of indefinite extensibility, and avails of hyperintensional epistemic two-dimensional semantics in order to account for the interaction between interpretational and objective modalities and the truthmakers thereof. This yields the first hyperintensional category theory in the literature. Elohim invents a new mathematical trick in which first-order structures are treated as categories, and Vopenka's principle can be satisfied because of the elementary embeddings between the categories and generate Vopenka cardinals in the category of Set in category theory. Chapter \textbf{13} examines modal responses to the alethic paradoxes. Elohim provides a counter-example to epistemic closure for logical deduction. Chapter \textbf{14} examines, finally, the modal and hyperintensional semantics for the different types of intention and the relation of the latter to evidential decision theory. (shrink)

I claim that Heisenberg’s notion of a closed theory and its analysis by Erhard Scheibe fit well with the philosophy of later Wittgenstein or its generalization. The notion of a closed theory corresponds to the notions of a form of life and rule/concept. I suggest the possibility of reconciling the views of Heisenberg, Dirac, and Bohr about inter-theoretical relations within a rational naturalistic pragmatism à la Wittgenstein and Robert Brandom’s analytic interpretation of Kantian synthetic unity of apperception. In particular, I (...) explain why a “closed theory” is “closed”, “accurate” (and even “perfect”), and “final” (as Heisenberg claims), and why it is also “open” and “approximate” in Dirac’s sense. That being said, unlike Alisa Bokulich (2004, 2006, 2008), I rather favour Heisenberg’s philosophical position. (shrink)