Actuality, Necessity, and Logical Truth

The traditional view that all logical truths are metaphysically necessary has come under attack in recent years. The contrary claim is prominent in David Kaplan’s work on demonstratives, and Edward Zalta has argued that logical truths that are not necessary appear in modal languages supplemented only with some device for making reference to the actual world (and thus independently of whether demonstratives like ‘I’, ‘here’, and ‘now’ are present). If this latter claim can be sustained, it strikes close to the heart of the traditional view. I begin this paper by discussing and refuting Zalta’s argument in the context of a language for propositional modal logic with an actuality connective (section 1). This involves showing that his argument in favor of real world validity his preferred explication of logical truth, is fallacious. Next (section 2) I argue for an alternative explication of logical truth called general validity. Since the rule of necessitation preserves general validity, the argument of section 2 provides a reason for affirming the traditional view. Finally (section 3) I show that the intuitive idea behind the discredited notion of real world validity finds legitimate expression in an object language connective for deep necessity. Earlier versions of this paper were read at the universities of Graz, Maribor, and Salzburg, and at a workshop on the philosophy of logic at the National Autonomous University of Mexico (UNAM) in Mexico City. My thanks to those present at these events for many helpful suggestions. Thanks are also due to an anonymous referee for Philosophical Studies.     

On Categories and A Posteriori Necessity: A Phenomenological Echo

This article argues for two related theses. First, it defends a general thesis: any kind of necessity, including metaphysical necessity, can only be known a priori. Second, however, it also argues that the sort of a priori involved in modal metaphysical knowledge is not related to imagination or any sort of so‐called epistemic possibility. Imagination is neither a proof of possibility nor a limit to necessity. Rather, modal metaphysical knowledge is built on intuition of philosophical categories and the structures they form.     

Causal Powers and the Necessity of Realization

Non-reductive physicalists hold that mental properties are realized by physical properties. The realization relation is typically taken to be a metaphysical necessitation relation. Here, I explore how the metaphysical necessitation feature of realization can be explained by what is known as ‘the subset view’ of realization. The subset view holds that the causal powers that are associated with a realized property are a proper subset of the causal powers that are associated with the realizer property. I argue that the said explanation of the metaphysical necessitation feature requires a careful treatment of the relationship between properties and causal powers.     

Recognition,Freedom, and the Self in Fichte's Foundations of Natural Right

In this paper I present an interpretation of J. G. Fichte's transcendental argument for the necessity of mutual recognition (Anerkennung) in Foundations of Natural Right. Fichte's argument purports to show that, as a condition of the possibility of self‐consciousness, we must take ourselves to stand in relations of mutual recognition with other agents like ourselves. After reconstructing the steps of Fichte's argument, I present what I call the ‘modal dilemma’, which highlights a serious ambiguity in Fichte's deduction. According to the modal dilemma, the conclusion to Fichte's transcendental argument—that as a condition of the possibility of our self‐consciousness, we must recognize and be recognized by others—expresses either metaphysical or normative necessity. However, no normative conclusion follows from Fichte's premises, and the metaphysical claim that does follow from his argument appears to be implausibly strong. Thus the argument looks like a failure on either interpretation of the conclusion's modality. In the penultimate section of the paper, I propose a new interpretation of the argument that avoids the modal dilemma and provides a normative grounding of Fichte's concept of right.     

JUSTIFYING METAPHYSICAL NIHILISM: A RESPONSE TO CAMERON

Ross Cameron charges the subtraction argument for metaphysical nihilism with equivocation: each premise is plausible only under different interpretations of 'concrete'. This charge is ungrounded; the argument is both valid and supported by basic modal intuitions.     

Genuine Violations of Laws

Could laws of nature be violated, in the sense that some proposition is both a law and false? I argue that opponents of regularity theories of laws should accept the metaphysical possibility of such genuine violations. I begin with a clarification of this claim. The main argument is then developed in three steps. I first argue that opponents of regularity theory should endorse the modal-essence view: certain modal principles are essential to the laws of nature. Second, I argue that the modal-essence view entails sophisticated modal primitivism. Third, I argue from sophisticated primitivism to the metaphysical possibility of genuine violations of laws.     

Modal Expansionism

There are various well-known paradoxes of modal recombination. This paper offers a solution to a variety of such paradoxes in the form of a new conception of metaphysical modality. On the proposed conception, metaphysical modality exhibits a type of indefinite extensibility. Indeed, for any objective modality there will always be some further, broader objective modality; in other terms, modal space will always be open to expansion.

     

Essence and modal knowledge

During the last quarter of a century, a number of philosophers have become attracted to the idea that necessity can be analyzed in terms of a hyperintensional notion of essence. One challenge for proponents of this view is to give a plausible explanation of our modal knowledge. The goal of this paper is to develop a strategy for meeting this challenge. My approach rests on an account of modality that I developed in previous work, and which analyzes modal properties in terms of the notion of a metaphysical law (which is a generalization of the concept of an essential truth). I discuss what information about the metaphysical laws (including essential truths) is required for modal knowledge. Moreover, I describe two ways in which we might be able to acquire this information. The first way employs inference to the best explanation. The metaphysical laws, including the essential truths, play a crucial role in causal and grounding explanations and we can gain knowledge of these laws by abductive inferences from facts of which we have perceptual or a priori knowledge. The second way of gaining information about the metaphysical laws rests on knowledge that is partly constitutive of competence with the concepts that are needed to express the relevant information. Finally, I consider how knowledge of the metaphysical laws can be used to establish modal claims, paying special attention to the much-discussed connection between conceiving and possibility.

     

The Argument for Subject Body Dualism from Transtemporal Identity Defended

In my argument for subject body dualism criticized by Ludwig I use the locution of a genuine and factual difference between two possibilities. Ludwig distinguishes three interpretations of this locution. According to his analysis the argument does not go through on any of these interpretations. In my response I agree that the argument is unsuccessful if ‘factual difference’ is understood in the first way. The second reading—according to a plausible understanding—cannot be used for the argument either. The discussion of this reading raises fundamental issues about different notions of propositional content. I disagree with Ludwig's diagnosis with respect to the third reading. Contrary to Ludwig's claim, there is no modal error involved if ‘factual difference’ is understood in the third way. Ludwig's objection to the argument according to its third reading can be answered by pointing out that every individual has its identity conditions necessarily. ¹ At this point fundamental and general metaphysical issues (concerning the link between identity conditions and the nature of ontological categories and between transworld and transtemporal identity) prove relevant. Finally, I make more explicit how ‘factual difference’ should be understood in the context of the argument (this is a fourth reading not considered by Ludwig) and explain how this reading strengthens the argument (compared to the third reading) by weakening its central premise. I conclude that Ludwig's attempt at undermining the argument from transtemporal identity for subject body dualism is unsuccessful.     

Autopoietic Enactivism,Phenomenology, and the Problem of Naturalism: A Neutral Monist Proposal

In this paper, I compare the original version of the enactive view—autopoietic enactivism—with Husserl’s phenomenology, regarding the issue of the relationship between consciousness and nature. I refer to this issue as the “problem of naturalism.” I show how the idea of the co-determination of subject and object of cognition, which is at the heart of autopoietic enactivism, is close to the phenomenological form of correlationism. However, I argue that there is a tension between an epistemological reading of the subject-object correlation that renounces to search for its metaphysical ground, and the enactivist focus on the biological basis of cognition, which seems to imply a view of nature as the metaphysical ground of the conscious mind. A similar problem arises in Husserl’s phenomenology in the contrast between the idea of the fundamental subject-object correlation, the concept of nature as a correlate of transcendental constitution, and the investigation of the corporeal and material grounding of consciousness. I find a way out of this problem by drawing on the distinction between static and genetic phenomenology. I argue that the investigation of the temporality of experience in genetic phenomenology leads us to investigate the metaphysical ground of the subject-object correlation, understood dynamically as co-constitution and co-origination. Then I propose to complement phenomenology and enactivism with a form of neutral monism, which conceives of the co-constitution of subject and object as grounded in a flow of fundamental, pre-phenomenal qualities.

     

How can we come to know metaphysical modal truths?

Those who aim to give an account of modal knowledge face two challenges: the integration challenge of reconciling an account of what is involved in knowing modal truths with a plausible story about how we can come to know them, and the reliability challenge of giving a plausible account of how we could have evolved a reliable capacity to acquire modal knowledge. I argue that recent counterfactual and dispositional accounts of modal knowledge cannot solve these problems regarding specifically metaphysical modal truths—leaving us with the threat of skepticism about large portions of metaphysics, and certain other areas of philosophy. I argue, however, that both of these problems look insuperable only if we assume that metaphysical modal discourse serves a describing or tracking function. If we adopt instead a normativist approach to metaphysical modal discourse, which sees the basic function of modal discourse as giving us perspicuous ways of conveying, reasoning with, and renegotiating semantic rules, the problems show up very differently. The modal normativist can give a plausible response to both of the classic problems of how we can come to know metaphysical modal truths.

     

Modal Objectivity1

It is widely agreed that the intelligibility of modal metaphysics has been vindicated. Quine's arguments to the contrary supposedly confused analyticity with metaphysical necessity, and rigid with non‐rigid designators.² But even if modal metaphysics is intelligible, it could be misconceived. It could be that metaphysical necessity is not absolute necessity – the strictest real (non‐epistemic, non‐deontic) notion of necessity – and that no proposition of traditional metaphysical interest is necessary in every real sense. If there were nothing otherwise “uniquely metaphysically significant” about metaphysical necessity, then paradigmatic metaphysical necessities would be necessary in one sense of “necessary”, not necessary in another, and that would be it. The question of whether they were necessary simpliciter would be like the question of whether the Parallel Postulate is true simpliciter – understood as a pure mathematical conjecture, rather than as a hypothesis about physical spacetime. In a sense, the latter question has no objective answer. In this article, I argue that paradigmatic questions of modal metaphysics are like the Parallel Postulate question. I then discuss the deflationary ramifications of this argument. I conclude with an alternative conception of the space of possibility. According to this conception, there is no objective boundary between possibility and impossibility. Along the way, I sketch an analogy between modal metaphysics and set theory.     

The Cogito and the Metaphysics of Mind

Descartes used the cogito to make two points the epistemological point that introspection affords us absolute certainty of our existence, and the metaphysical point that subjects are thinking things logically distinct from bodies. Most philosophers accept Descartes’s epistemological claim but reject his metaphysical claim. I argue that we cannot do this if the cogito works, then subjects are non-physical. Although I refrain from endorsing an argument for dualism based on this conditional, I discuss how such an argument would differ from the conceivability arguments pursued by Descartes in the Sixth Meditation and by contemporary philosophers. Unlike those arguments, this argument would not be refuted by the discovery of a posteriori identities between physical and phenomenological properties. In other words, it is possible to argue for substance dualism even if phenomenal properties are physical properties.     

THE TROUBLE WITH MARY

Abstract: Two arguments are famously held to support the conclusion that consciousness cannot be explained in purely physical or functional terms – hence, that physicalism is false: the modal argument and the knowledge argument. While anti‐physicalists appeal to both arguments, this paper argues there is a methodological incoherence in jointly maintaining them: the modal argument supports the possibility of zombies; but the possibility of zombies undercuts the knowledge argument. At best, this leaves anti‐physicalists in a considerably weakened rhetorical position. At worst, it shows that commonsense intuitions on which anti‐physicalists rely mislead us about the true nature of conscious experience.     

Continuity of change in Kant’s dynamics

Since his Metaphysische Anfangsgründe der Naturwissenschaft was first published in 1786, controversy has surrounded Immanuel Kant’s conception of matter. In particular, the justification for both his dynamical theory of matter and the related dismissal of mechanical philosophy are obscure. In this paper, I address these longstanding issues and establish that Kant’s dynamism rests upon Leibnizian, metaphysical commitments held by Kant from his early pre-Critical texts on natural philosophy to his major critical works. I demonstrate that, throughout his corpus and inspired by Leibniz, Kant endorses the a priori law of continuity of alteration as a truth of metaphysics, according to which all alterations in experience must occur gradually through all intervening degrees. The principle thus legislates against mechanical philosophy’s absolutely impenetrable atoms, as they would would involve instantaneous changes of velocity in impact. This reveals the metaphysical incoherencies in mechanical philosophy and leaves Kant’s own dynamical theory of matter, grounded on material forces, as the only viable approach to physical explanation. Subsequently, I demonstrate that Kant nevertheless made conceptual space in his system for the theoretical consideration of mechanical explanations, which makes manifest one of the positive roles that the faculty of reason can play with respect to natural science.

     

THE MODAL ARGUMENT FOR A PRIORI JUSTIFICATION

Kant famously argued that, from experience, we can only learn how something actually is, but not that it must be so. In this paper, I defend an improved version of Kant's argument for the existence of a priori knowledge, the Modal Argument , against recent objections by Casullo and Kitcher. For the sake of the argument, I concede Casullo's claim that we may know certain counterfactuals in an empirical way and thereby gain epistemic access to some nearby, nomologically possible worlds. But I maintain that our beliefs about metaphysical necessities still cannot be justified empirically. Furthermore, I reject Casullo's deflationary thesis about the significance of such justification. Kitcher's most troublesome objection is that we can gain any modal justification whatsoever through testimony , i.e. in an experiential way. This can be countered by distinguishing between productive sources of justification, like perception, and merely reproductive sources, like testimony. Thus, some productive a priori source will always be needed somewhere. ¹     

Does the deduction theorem fail for modal logic?

Various sources in the literature claim that the deduction theorem does not hold for normal modal or epistemic logic, whereas others present versions of the deduction theorem for several normal modal systems. It is shown here that the apparent problem arises from an objectionable notion of derivability from assumptions in an axiomatic system. When a traditional Hilbert-type system of axiomatic logic is generalized into a system for derivations from assumptions, the necessitation rule has to be modified in a way that restricts its use to cases in which the premiss does not depend on assumptions. This restriction is entirely analogous to the restriction of the rule of universal generalization of first-order logic. A necessitation rule with this restriction permits a proof of the deduction theorem in its usual formulation. Other suggestions presented in the literature to deal with the problem are reviewed, and the present solution is argued to be preferable to the other alternatives. A contraction- and cut-free sequent calculus equivalent to the Hilbert system for basic modal logic shows the standard failure argument untenable by proving the underivability of ${\square\,A}$ from A.     

On the Possibility of Skeptical Scenarios

Abstract: It is generally accepted that skeptical scenarios must be possible to raise legitimate skeptical doubt. I argue that if the possibility in question is supposed to be genuine metaphysical possibility, the skeptic's reasoning does not straightforwardly succeed. I first motivate the metaphysical possibility requirement on skeptical scenarios: it's a plausible position that several authors accept and that a family of prominent views—sensitivity, safety, relevant alternatives—are committed to. I argue that plausible constraints in modal epistemology show that justification for believing that certain global skeptical scenarios are metaphysically possible rests on some justified beliefs about the external world, and that this undermines the skeptical argument. While there may still be local skeptical challenges, skeptics cannot appeal to the metaphysical possibility of skeptical scenarios to generate global external world skepticism.     

Vagueness and the Metaphysics of Consciousness

An argument is offered for this conditional: If our current concept conscious state is sharp rather than vague, and also correct (at least in respect of its sharpness), then common versions of familiar metaphysical theories of consciousness are false – namely versions of the identity theory, functionalism, and dualism that appeal to complex physical or functional properties in identification, realization, or correlation. Reasons are also given for taking seriously the claim that our current concept conscious state is sharp. The paper ends by surveying the theoretical options left open by the concept’s sharpness and the truth of the conditional argued for in the paper.