What sort of logic do we get if we adopt a supervaluational semantics for vagueness? As it turns out, the answer depends crucially on how the standard notion of validity as truth preservation is recasted. There are several ways of doing that within a supervaluational framework, the main alternative being between “global” construals (e.g., an argument is valid iff it preserves truth-under-all-precisifications) and “local” construals (an argument is valid iff, under all precisifications, it preserves truth). The former alternative is by (...) far more popular, but I argue in favor of the latter, for (i) it does not suffer from a number of serious objections, and (ii) it makes it possible to restore global validity as a defined notion. (shrink)

I focus on three mereological principles: the Extensionality of Parthood (EP), the Uniqueness of Composition (UC), and the Extensionality of Composition (EC). These principles are not equivalent. Nonetheless, they are closely related (and often equated) as they all reflect the basic nominalistic dictum, No difference without a difference maker. And each one of them—individually or collectively—has been challenged on philosophical grounds. In the first part I argue that such challenges do not quite threaten EP insofar as they are either self-defeating (...) or unsupported. In the second part I argue that they hardly undermine the tenability of EC and UC as well. (shrink)

I argue that Universalism (the thesis that mereological composition is unrestricted) entails Extensionalism (the thesis that sameness of composition is sufficient for identity) as long as the parthood relation is transitive and satisfies the Weak Supplementation principle (to the effect that whenever a thing has a proper part, it has another part disjoint from the first).

One logic or many? I say—many. Or rather, I say there is one logic for each way of specifying the class of all possible circumstances, or models, i.e., all ways of interpreting a given language. But because there is no unique way of doing this, I say there is no unique logic except in a relative sense. Indeed, given any two competing logical theories T1 and T2 (in the same language) one could always consider their common core, T, and settle (...) on that theory. So, given any language L, one could settle on the minimal logic T0 corresponding to the common core shared by all competitors. That would be a way of resisting relativism, as long as one is willing to redraw the bounds of logic accordingly. However, such a minimal theory T0 may be empty if the syntax of L contains no special ingredients the interpretation of which is independent of the specification of the relevant L-models. And generally—I argue—this is indeed the case. (shrink)

ABSTRACTEvaluative aesthetic discourse communicates that the speaker has had first-hand experience of what is talked about. If you call a book bewitching, it will be assumed that you have read the book. If you say that a building is beautiful, it will be assumed that you have had some visual experience with it. According to an influential view, this is because knowledge is a norm for assertion, and aesthetic knowledge requires first-hand experience. This paper criticizes this view and argues for (...) an alternative view, according to which aesthetic discourse expresses affective states of mind, analogously to how assertions express beliefs. It is because these affective states require first-hand experience that aesthetic discourse communicates that such acquaintance is at hand. The paper furthermore argues that the lack of an experience requirement for aesthetic belief ascriptions constitutes a problem for the kind of expressivist who claims that evaluative belief states are covert non-cognitive states. (shrink)

In the first section, I characterize skeptical theism more fully. This is necessary in order to address some important misconceptions and mischaracterizations that appear in the essays by Maitzen, Wilks, and O’Connor. In the second section, I describe the most important objections they raise and group them into four “families” so as to facilitate an orderly series of responses. In the four sections that follow, I respond to the objections.

It is widely held within contemporary metaethics that there is a lack of linguistic support for evaluative expressivism. On the contrary, it seems that the predictions that expressivists make about evaluative discourse are not borne out. An instance of this is the so-called problem of missing Moorean infelicity. Expressivists maintain that evaluative statements express non-cognitive states of mind in a similar manner to how ordinary descriptive language expresses beliefs. Conjoining an ordinary assertion that p with the denial of being in (...) the corresponding belief state famously gives rise to Moorean infelicity:?? It’s raining but I don’t believe that it’s raining. If expressivists are right, then conjoining evaluative statements with the denial of being in the relevant non-cognitive state of mind should give rise to similar infelicity. However, as several theorists have pointed out, this does not seem to be the case. Statements like the following are not infelicitous: Murder is wrong but I don’t disapprove of it. In this paper, I argue that evaluative statements express the kind of states that are attributed by ‘find’-constructions in English and that these states are non-cognitive in nature. This addresses the problem of missing Moorean infelicity and, more generally, goes to show that there are linguistic facts which support expressivism about evaluative discourse. (shrink)

Ian Rumfitt has proposed systems of bilateral logic for primitive speech acts of assertion and denial, with the purpose of ‘exploring the possibility of specifying the classically intended senses for the connectives in terms of their deductive use’ : 810f). Rumfitt formalises two systems of bilateral logic and gives two arguments for their classical nature. I assess both arguments and conclude that only one system satisfies the meaning-theoretical requirements Rumfitt imposes in his arguments. I then formalise an intuitionist system of (...) bilateral logic which also meets those requirements. Thus Rumfitt cannot claim that only classical bilateral rules of inference succeed in imparting a coherent sense onto the connectives. My system can be extended to classical logic by adding the intuitionistically unacceptable half of a structural rule Rumfitt uses to codify the relation between assertion and denial. Thus there is a clear sense in which, in the bilateral framework, the difference between classicism and intuitionism is not one of the rules of inference governing negation, but rather one of the relation between assertion and denial. (shrink)

This paper discusses proof-theoretic semantics, the project of specifying the meanings of the logical constants in terms of rules of inference governing them. I concentrate on Michael Dummett’s and Dag Prawitz’ philosophical motivations and give precise characterisations of the crucial notions of harmony and stability, placed in the context of proving normalisation results in systems of natural deduction. I point out a problem for defining the meaning of negation in this framework and prospects for an account of the meanings of (...) modal operators in terms of rules of inference. (shrink)

The outcomes of sports and competitive games excite intense emotions in many people, even when those same people acknowledge that those outcomes are of trifling importance. I call this incongruity between the judged importance of the outcome and the intense reactions it provokes the Puzzle of Sport. The puzzle can be usefully compared to another puzzle in aesthetics: the Paradox of Fiction, which asks how it is we become emotionally caught up with events and characters we know to be unreal. (...) In this article, I examine the prospects of understanding our engagement with competitive games on the model of our engagement with works of fiction, thus enabling analogous explanations for both puzzles. I show that there are significant problems with such an approach and offer an alternative, mobilizing ideas from David Velleman and Thomas Nagel, that appeals to the volatility of our motivational attitudes. (shrink)

A well-known theory about under which circumstances a statement is true in a fiction is The Reality Principle, which originate in the work of David Lewis: (RP) Where p1... pn are the primary fictional truths of a fiction F , it is true in F that q iff the following holds: were p1 ... pn the case, q would have been the case (Walton 1990: 44). RP has been subjected to a number of counterexamples, up to a point where, in (...) the words of Stacie Friend “it is widely recognized that the Reality Principle […] cannot be a universal inference rule for implied story-truths” (Friend 2017: 33). This chapter argues that the strength of these counterexamples is widely overestimated, and that they do not, on closer scrutiny, constitute reasons for rejecting RP. (shrink)

There is much discussion about whether the human mind is a computer, whether the human brain could be emulated on a computer, and whether at all physical entities are computers (pancomputationalism). These discussions, and others, require criteria for what is digital. I propose that a state is digital if and only if it is a token of a type that serves a particular function - typically a representational function for the system. This proposal is made on a syntactic level, assuming (...) three levels of description (physical, syntactic, semantic). It suggests that being digital is a matter of discovery or rather a matter of how we wish to describe the world, if a functional description can be assumed. Given the criterion provided and the necessary empirical research, we should be in a position to decide on a given system (e.g. the human brain) whether it is a digital system and can thus be reproduced in a different digital system (since digital systems allow multiple realization). (shrink)

Since the 1960s, metaphysics has flourished in Anglo-American philosophy. Far from wanting to avoid metaphysics, philosophers have embraced it in droves. There have been critics, to be sure; but the criticisms have received answers and the enterprise has carried on.

In "Rethinking Sadomasochism," Patrick Hopkins challenges the "radical" feminist claim that sadomasochism is incompatible with feminism. He does so by appeal to the notion of "simulation." I argue that Hopkins's conclusions are generally right, but they cannot be inferred from his "simulation" argument. I replace Hopkins's "simulation" with Kendall Walton's more sophisticated theory of "make-believe." I use this theory to better argue that privately conducted sadomasochism is compatible with feminism.

In bilateral logic formulas are signed by + and –, indicating the speech acts assertion and denial. I argue that making an assumption is also speech act. Speech acts cannot be embedded within other speech acts. Hence we cannot make sense of the notion of making an assumption in bilateral logic. Attempts to solve this problem are considered and rejected.

The focus of this paper are Dummett's meaning-theoretical arguments against classical logic based on consideration about the meaning of negation. Using Dummettian principles, I shall outline three such arguments, of increasing strength, and show that they are unsuccessful by giving responses to each argument on behalf of the classical logician. What is crucial is that in responding to these arguments a classicist need not challenge any of the basic assumptions of Dummett's outlook on the theory of meaning. In particular, I (...) shall grant Dummett his general bias towards verificationism, encapsulated in the slogan 'meaning is use'. The second general assumption I see no need to question is Dummett's particular breed of molecularism. Some of Dummett's assumptions will have to be given up, if classical logic is to be vindicated in his meaning-theoretical framework. A major result of this paper will be that the meaning of negation cannot be defined by rules of inference in the Dummettian framework. (shrink)

This paper studies a formalisation of intuitionistic logic by Negri and von Plato which has general introduction and elimination rules. The philosophical importance of the system is expounded. Definitions of ‘maximal formula’, ‘segment’ and ‘maximal segment’ suitable to the system are formulated and corresponding reduction procedures for maximal formulas and permutative reduction procedures for maximal segments given. Alternatives to the main method used are also considered. It is shown that deductions in the system convert into normal form and that deductions (...) in normal form have the subformula property. (shrink)

This paper presents a sequent calculus and a dual domain semantics for a theory of definite descriptions in which these expressions are formalised in the context of complete sentences by a binary quantifier I. I forms a formula from two formulas. Ix[F, G] means ‘The F is G’. This approach has the advantage of incorporating scope distinctions directly into the notation. Cut elimination is proved for a system of classical positive free logic with I and it is shown to be (...) sound and complete for the semantics. The system has a number of novel features and is briefly compared to the usual approach of formalising ‘the F ’ by a term forming operator. It does not coincide with Hintikka’s and Lambert’s preferred theories, but the divergence is well-motivated and attractive. (shrink)

In this paper, I'll present a general way of "reading off" introduction/elimination rules from elimination/introduction rules, and define notions of harmony and stability on the basis of it.

This brief note corrects an error in one of the reduction steps in my paper 'Normalisation for Bilateral Classical Logic with some Philosophical Remarks' published in the Journal of Applied Logics 8/2 (2021): 531-556.

Sentences containing definite descriptions, expressions of the form ‘The F’, can be formalised using a binary quantifier ι that forms a formula out of two predicates, where ιx[F, G] is read as ‘The F is G’. This is an innovation over the usual formalisation of definite descriptions with a term forming operator. The present paper compares the two approaches. After a brief overview of the system INFι of intuitionist negative free logic extended by such a quantifier, which was presented in (...) (Kürbis 2019), INFι is first compared to a system of Tennant’s and an axiomatic treatment of a term forming ι operator within intuitionist negative free logic. Both systems are shown to be equivalent to the subsystem of INFι in which the G of ιx[F, G] is restricted to identity. INFι is then compared to an intuitionist version of a system of Lambert’s which in addition to the term forming operator has an operator for predicate abstraction for indicating scope distinctions. The two systems will be shown to be equivalent through a translation between their respective languages. Advantages of the present approach over the alternatives are indicated in the discussion. (shrink)

In this commentary, I suggest expanding the deliberative aspects of critical care policy development in two ways. First, critical-care policy development should expand the scope of deliberation by leaving fewer issues up to expertise or private choice. For instance. it should allow deliberation about the relevance of age, disability, social position, and psychological well-being to allocation decisions. Second, it should broaden both the set of costs considered and the set of stakeholders represented in the deliberative process. In particular, it should (...) consider efforts to reduce the cost of end-of-life care and to redirect resources away from the provision of costly interventions, and should expand the set of individuals included in deliberation to include stakeholders outside the health-care system. (shrink)

Molnar argues that the problem of truthmakers for negative truths arises because we tend to accept four metaphysical principles that entail that all negative truths have positive truthmakers. This conclusion, however, already follows from only three of Molnar´s metaphysical principles. One purpose of this note is to set the record straight. I provide an alternative reading of two of Molnar´s principles on which they are all needed to derive the desired conclusion. Furthermore, according to Molnar, the four principles may be (...) inconsistent. By themselves, however, they are not. The other purpose of this note is to propose some plausible further principles that, when added to the four metaphysical theses, entail a contradiction. (shrink)

Will future lethal autonomous weapon systems (LAWS), or ‘killer robots’, be a threat to humanity? The European Parliament has called for a moratorium or ban of LAWS; the ‘Contracting Parties to the Geneva Convention at the United Nations’ are presently discussing such a ban, which is supported by the great majority of writers and campaigners on the issue. However, the main arguments in favour of a ban are unsound. LAWS do not support extrajudicial killings, they do not take responsibility away (...) from humans; in fact they increase the abil-ity to hold humans accountable for war crimes. Using LAWS in war would probably reduce human suffering overall. Finally, the availability of LAWS would probably not increase the probability of war or other lethal conflict—especially as compared to extant remote-controlled weapons. The widespread fear of killer robots is unfounded: They are probably good news. (shrink)

The thesis of this paper is that utopianism is a theoretical necessity—we couldn’t, for example, engage in normative political philosophy without it—and, further, that in consciously embracing utopianism we will consequently experience an enrichment of our political lives. Thus, the title of my paper has a double meaning: it highlights the fact that utopianism always plays a normative role in political philosophy, as its concern is inevitably the promotion of a certain vision of the good life; and secondly it suggests (...) that there normatively ‘ought to be’ a recognized and respectable role for utopianism within political philosophy. The first meaning, I believe, is self-explanatory. Regarding the second, it expresses my hope to— in short— take what is old, and through a modest process of rehabilitation, make it new again. (shrink)

This note corrects an error in my paper 'Normalisation and Subformula Property for a System of Classical Logic with Tarski's Rule' (Archive for Mathematical Logic 61 (2022): 105-129, DOI 10.1007/s00153-021-00775-6): Theorem 2 is mistaken, and so is a corollary drawn from it as well as a corollary that was concluded by the same mistake. Luckily this does not affect the main result of the paper.

One of the most historically recent and damaging blows to the reputation of utopianism came from its association with the totalitarian regimes of Hitler’s Third Reich and Mussolini’s Fascist party in World War II and the prewar era. Being an apologist for utopianism, it seemed to some, was tantamount to being an apologist for Nazism and all of its concomitant horrors. The fantasy principle of utopia was viewed as irretrievably bound up with the irrationalism of modern dictatorship. While these conclusions (...) are somewhat understandable given the broad strokes that definitions of utopia are typically painted with, I will show in this paper that the link between the mythos of fascism and the constructs of utopianism results from an unfortunate conflation at the theoretical level. The irrationalism of any mass ethos and the rationalism of the thoughtful utopian planner are, indeed, completely at odds with each other. I arrive at this conclusion via an analysis of the concepts of myth and narrative, and the relationships these have with the concept of utopia. (shrink)

The fundamental assumption of Dummett’s and Prawitz’ proof-theoretic justification of deduction is that ‘if we have a valid argument for a complex statement, we can construct a valid argument for it which finishes with an application of one of the introduction rules governing its principal operator’. I argue that the assumption is flawed in this general version, but should be restricted, not to apply to arguments in general, but only to proofs. I also argue that Dummett’s and Prawitz’ project of (...) providing a logical basis for metaphysics only relies on the restricted assumption. (shrink)

Tailoring the design of robot bodies for control purposes is implicitly performed by engineers, however, a methodology or set of tools is largely absent and optimization of morphology (shape, material properties of robot bodies, etc.) is lag- ging behind the development of controllers. This has become even more prominent with the advent of compliant, deformable or "soft" bodies. These carry substantial potential regarding their exploitation for control – sometimes referred to as "mor- phological computation" in the sense of offloading computation (...) needed for control to the body. Here, we will argue in favor of a dynamical systems rather than com- putational perspective on the problem. Then, we will look at the pros and cons of simple vs. complex bodies, critically reviewing the attractive notion of “soft” bodies automatically taking over control tasks. We will address another key dimension of the design space – whether model-based control should be used and to what extent it is feasible to develop faithful models for different morphologies. ----- This paper was also published in the 2014 AISB proceedings http://aisb50.org/representation-of-reality-humans-animals-and-machines/ - http://doc.gold.ac.uk/aisb50/. (shrink)

I want to suggest that the major influence of classical arguments for embodiment like "The Embodied Mind" by Varela, Thomson & Rosch (1991) has been a changing of positions rather than a refutation: Cognitivism has found ways to retreat and regroup at positions that have better fortification, especially when it concerns theses about artificial intelligence or artificial cognitive systems. For example: a) Agent-based cognitivism' that understands humans as taking in representations of the world, doing rule-based processing and then acting on (...) them (sense-plan-act) is often limited to conscious decision processes; and b) Purely syntactic cognition is compatible with embodiment, or supplemented by embodiment (e.g. for 'grounding'). While the empirical thesis of embodied cognition ('embodied cognitive science') is true and the practical engineering thesis ('morphological computation', 'cheap design') is often true, the conceptual thesis ('embodiment is necessary for cognition') is likely false - syntax is often enough for cognition, unless grounding is really necessary. I conclude that it has become more sensible to integrate embodiment with traditional approaches rather than "fight for embodiment" or "against cognitivism". (shrink)

Within contemporary metaethics, it is widely held that there is a “presumption of realism” in moral thought and discourse. Anti-realist views, like error theory and expressivism, may have certain theoretical considerations speaking in their favor, but our pretheoretical stance with respect to morality clearly favors objectivist metaethical views. This article argues against this widely held view. It does so by drawing from recent discussions about so-called “subjective attitude verbs” in linguistics and philosophy of language. Unlike pretheoretically objective predicates (e.g., “is (...) made of wood”, “is 185 cm tall”), moral predicates embed felicitously under subjective attitude verbs like the English “find”. Moreover, it is argued that the widespread notion that moral discourse bears all the marks of fact-stating discourse is rooted in a blinkered focus on examples from English. Cross-linguistic considerations suggest that subjective attitude verbs are actually the default terms by which we ascribe moral views to people. Impressions to the contrary in English have to do with some unfortunate quirks of the term “think”. (shrink)

Bilateralists hold that the meanings of the connectives are determined by rules of inference for their use in deductive reasoning with asserted and denied formulas. This paper presents two bilateral connectives comparable to Prior's tonk, for which, unlike for tonk, there are reduction steps for the removal of maximal formulas arising from introducing and eliminating formulas with those connectives as main operators. Adding either of them to bilateral classical logic results in an incoherent system. One way around this problem is (...) to count formulas as maximal that are the conclusion of reductio and major premise of an elimination rule and to require their removability from deductions. The main part of the paper consists in a proof of a normalisation theorem for bilateral logic. The closing sections address philosophical concerns whether the proof provides a satisfactory solution to the problem at hand and confronts bilateralists with the dilemma that a bilateral notion of stability sits uneasily with the core bilateral thesis. (shrink)

Cognitive penetration of perception is the idea that what we see is influenced by such states as beliefs, expectations, and so on. A perceptual belief that results from cognitive penetration may be less justified than a nonpenetrated one. Inferentialism is a kind of internalist view that tries to account for this by claiming that some experiences are epistemically evaluable, on the basis of why the perceiver has that experience, and the familiar canons of good inference provide the appropriate standards by (...) which experiences are evaluated. I examine recent defenses of inferentialism by Susanna Siegel, Peter Markie, and Matthew McGrath and argue that the prospects for inferentialism are dim. (shrink)

The philosophy of AI has seen some changes, in particular: 1) AI moves away from cognitive science, and 2) the long term risks of AI now appear to be a worthy concern. In this context, the classical central concerns – such as the relation of cognition and computation, embodiment, intelligence & rationality, and information – will regain urgency.

There is widespread agreement that while on a Dummettian theory of meaning the justified logic is intuitionist, as its constants are governed by harmonious rules of inference, the situation is reversed on Huw Price's bilateralist account, where meanings are specified in terms of primitive speech acts assertion and denial. In bilateral logics, the rules for classical negation are in harmony. However, as it is possible to construct an intuitionist bilateral logic with harmonious rules, there is no formal argument against intuitionism (...) from the bilateralist perspective. Price gives an informal argument for classical negation based on a pragmatic notion of belief, characterised in terms of the differences they make to speakers' actions. The main part of this paper puts Price's argument under close scrutiny by regimenting it and isolating principles Price is committed to. It is shown that Price should draw a distinction between A or ¬A making a difference. According to Price, if A makes a difference to us, we treat it as decidable. This material allows the intuitionist to block Price's argument. Abandoning classical logic also brings advantages, as within intuitionist logic there is a precise meaning to what it might mean to treat A as decidable: it is to assume A ∨ ¬A. (shrink)

Persons are widely believed to be rational, planning agents that are both author and main character of their life stories. A major goal is to keep these narratives coherent as they unfold, and part of a fulfilled life allegedly stems from this coherence. My aim is to challenge these convictions by considering two related claims about persons and their lives. Contrary to the widespread theoretical conviction in philosophy of mind and action, persons are fundamentally emotional and affective rather than rational (...) and deliberative beings. And so, on a practical level, persons need not constantly aspire to integrate their past, present, and future into a coherent whole in order to live fulfilled lives. Needless to say, I cannot hope to defend these claims and their relation in great detail with a few brief strokes. In addition to theoretical reflections, I discuss some practical implications and potential benefits that come with discarding the daunting task of continuously keeping track of one's life story. Drawing on insights from a contemplative Buddhist tale, I venture that the practice of letting go can break the spell, and give rise to an alleviating source of liberation from life's troubles.Export citation. (shrink)

Intentions are commonly conceived of as discrete mental states that are the direct cause of actions. In the last several decades, neuroscientists have taken up the project of finding the neural implementation of intentions, and a number of areas have been posited as implementing these states. We argue, however, that the processes underlying action initiation and control are considerably more dynamic and context sensitive than the concept of intention can allow for. Therefore, adopting the notion of ‘intention’ in neuroscientific explanations (...) can easily lead to misinterpretation of the data, and can negatively influence investigation into the neural correlates of intentional action.We suggest reinterpreting the mechanisms underlying intentional action, and we will discuss the elements that such a reinterpretation needs to account for. (shrink)

This is a commentary on MM McCabe's "First Chop your logos... Socrates and the sophists on language, logic, and development". In her paper MM analyses Plato's Euthydemos, in which Plato tackles the problem of falsity in a way that takes into account the speaker and complements the Sophist's discussion of what is said. The dialogue looks as if it is merely a demonstration of the silly consequences of eristic combat. And so it is. But a main point of MM's paper (...) is that there is serious philosophy in the Euthydemos, too. MM argues that to counter the sophist brothers Euthydemos and Dionysodoros, Socrates points out that that there are different aspects to the verb 'to say' that run in parallel to the different aspects of the very 'to learn'. So just as there is continuity rather than ambiguity between 'to learn' and 'to understand', so there is continuity between the different aspects of saying. Thus Socrates puts forward a teleological account of both learning and meaning. Following up on some of MM's thoughts, I argue that the sophists subscribe, despite appearance, to a theory of meaning that respects serious and widely accepted philosophical theses on meaning. -/- Forthcoming in the Australasian Philosophical Review. The curator of the volume is Fiona Leigh, and the committee also has Hugh Benson and Tim Clarke. You can find MM's paper as well as the commentaries by Nicholas Denyer and Russell E. Jones and Ravi Sharma (and myself) by registering. (shrink)

This paper presents a way of formalising definite descriptions with a binary quantifier ι, where ιx[F, G] is read as ‘The F is G’. Introduction and elimination rules for ι in a system of intuitionist negative free logic are formulated. Procedures for removing maximal formulas of the form ιx[F, G] are given, and it is shown that deductions in the system can be brought into normal form.

This paper considers a formalisation of classical logic using general introduction rules and general elimination rules. It proposes a definition of ‘maximal formula’, ‘segment’ and ‘maximal segment’ suitable to the system, and gives reduction procedures for them. It is then shown that deductions in the system convert into normal form, i.e. deductions that contain neither maximal formulas nor maximal segments, and that deductions in normal form satisfy the subformula property. Tarski’s Rule is treated as a general introduction rule for implication. (...) The general introduction rule for negation has a similar form. Maximal formulas with implication or negation as main operator require reduction procedures of a more intricate kind not present in normalisation for intuitionist logic. (shrink)

Rumfitt has given two arguments that in unilateralist verificationist theories of meaning, truth collapses into correct assertibility. In the present paper I give similar arguments that show that in unilateral falsificationist theories of meaning, falsehood collapses into correct deniability. According to bilateralism, meanings are determined by assertion and denial conditions, so the question arises whether it succumbs to similar arguments. I show that this is not the case. The final section considers the question whether a principle central to Rumfitt's first (...) argument, ‘It is assertible that if and only if it is assertible that it is assertible that ’, is one that bilateralists can reject, and concludes that they cannot. It follows that the logic of assertibility and deniability, according to a result by Williamson, is the little known modal logic K4 studied by Sobociński. The paper ends with a plaidoyer for bilateralists to adopt this logic. (shrink)

This paper formulates a bilateral account of harmony that is an alternative to one proposed by Francez. It builds on an account of harmony for unilateral logic proposed by Kürbis and the observation that reading the rules for the connectives of bilateral logic bottom up gives the grounds and consequences of formulas with the opposite speech act. I formulate a process I call 'inversion' which allows the determination of assertive elimination rules from assertive introduction rules, and rejective elimination rules from (...) rejective introduction rules, and conversely. It corresponds to Francez's notion of vertical harmony. I also formulate a process I call 'conversion', which allows the determination of rejective introduction rules from assertive elimination rules and conversely, and the determination of assertive introduction rules from rejective elimination rules and conversely. It corresponds to Francez's notion of horizontal harmony. The account has a number of features that distinguish it from Francez's. (shrink)

Bilateralists, who accept that there are two primitive speech acts, assertion and denial, can offer an attractive definition of consequence: Y follows from X if and only if it is incoherent to assert all formulas X and to deny all formulas Y. The present paper argues that this definition has consequences many will find problematic, amongst them that truth coincides with assertibility. Philosophers who reject these consequences should therefore reject this definition of consequence.

Supervenience in metaethics is the notion that there can be no moral dif-ference between two acts, persons or events without some non-moral difference underlying it. If St. Francis is a good man, there could not be a man exactly like St. Francis in non-evaluative respects that is not good. The phenomenon was first systematically discussed by R. M. Hare (1952), who argued that realists about evaluative properties struggle to account for it. As is well established, Hare, and following him, Simon (...) Blackburn, mistakenly took the relevant phenomenon to be weak rather than strong supervenience, and the explanations they offered for it are accordingly outdated. In this paper, I present a non-factualist account of strong su-pervenience of the evaluative and argue that it fares better than compet-ing realist views in explaining the conceptual nature of the phenomenon, as well as in offering an account of the supervenience of the evaluative in general, rather than more narrowly the moral. While Hare and Blackburn were wrong about the specifics, they were right in that non-factualists can offer a plausible account of the supervenience of the evaluative, that in certain respects is superior to competing realist explanations. (shrink)

This paper presents rules of inference for a binary quantifier I for the formalisation of sentences containing definite descriptions within intuitionist positive free logic. I binds one variable and forms a formula from two formulas. Ix[F, G] means ‘The F is G’. The system is shown to have desirable proof-theoretic properties: it is proved that deductions in it can be brought into normal form. The discussion is rounded up by comparisons between the approach to the formalisation of definite descriptions recommended (...) here and the more usual approach that uses a term-forming operator ι, where ιxF means ‘the F’. (shrink)

Thought experiments that concoct bizarre possible world modalities are standard fare in debates on personal identity. Appealing to intuitions raised by such evocations is often taken to settle differences between conflicting theoretical views that, albeit, have practical implications for ethical controversies of personal identity in health care. Employing thought experiments that way is inadequate, I argue, since personhood is intrinsically linked to constraining facts about the actual world. I defend a moderate modal skepticism according to which intuiting across conceptually incongruent (...) worlds constitutes ‘invalid intuitioninferences’—i.e., carrying over intuitions gathered from facts about possible worlds that are at odds with facts about the actual world, for the purpose of making claims about real-life persons and their identity, leads to conceptual incongruences. Such a methodological fallout precludes accurate, informative judgments about personal identity in the actual world, calling into question the adequacy of thought experimental considerations for potential real world applications in medical ethics. (shrink)

This paper draws attention to a proof of the necessity of identity given by Arthur Prior. In its simplicity, it is comparable to a proof of Quine's, popularised by Kripke, but it is slightly different. Prior's Polish notation is transcribed into a more familiar idiom. Prior's proof is followed by a proof of the necessity of difference, possibly the first such proof in the literature, which is also repeated here and transcribed. The paper concludes with a brief discussion of Prior's (...) views on identity and difference over time. (shrink)

The problem of negative truth is the problem of how, if everything in the world is positive, we can speak truly about the world using negative propositions. A prominent solution is to explain negation in terms of a primitive notion of metaphysical incompatibility. I argue that if this account is correct, then minimal logic is the correct logic. The negation of a proposition A is characterised as the minimal incompatible of A composed of it and the logical constant ¬. A (...) rule based account of the meanings of logical constants that appeals to the notion of incompatibility in the introduction rule for negation ensures the existence and uniqueness of the negation of every proposition. But it endows the negation operator with no more formal properties than those it has in minimal logic. (shrink)