This paper examines the question of the extensional correctness of Tarskian definitions of logical truth and logical consequence. I identify a few different informal properties which are necessary for a sentence to be an informal logical truth and look at whether they are necessary properties of Tarskian logical truths. I examine arguments by John Etchemendy and Vann McGee to the effect that some of those properties are not necessary properties of some Tarskian logical (...) truths, and find them unconvincing. I stress the point that since the hypothesis that Tarski's definitions are extensionally correct is deeply entrenched, the burden of proof is still on the shoulders of Tarski's critics, who have not lifted the burden. (shrink)

The starting point of this paper concerns the apparent difference between what we might call absolute truth and truth in a model, following Donald Davidson. The notion of absolute truth is the one familiar from Tarski’s T-schema: ‘Snow is white’ is true if and only if snow is white. Instead of being a property of sentences as absolute truth appears to be, truth in a model, that is relative truth, is evaluated in terms of (...) the relation between sentences and models. I wish to examine the apparent dual nature of logical truth (without dwelling on Davidson), and suggest that we are dealing with a distinction between a metaphysical and a linguistic interpretation of truth. I take my cue from John Etchemendy, who suggests that absolute truth could be considered as being equivalent to truth in the ‘right model’, i.e., the model that corresponds with the world. However, the notion of ‘model’ is not entirely appropriate here as it is closely associated with relative truth. Instead, I propose that the metaphysical interpretation of truth may be illustrated in modal terms, by metaphysical modality in particular. One of the tasks that I will undertake in this paper is to develop this modal interpretation, partly building on my previous work on the metaphysical interpretation of the law of non-contradiction (Tahko 2009). After an explication of the metaphysical interpretation of logical truth, a brief study of how this interpretation connects with some recent important themes in philosophical logic follows. In particular, I discuss logical pluralism and propose an understanding of pluralism from the point of view of the metaphysical interpretation. (shrink)

Translated from: W.V.O.Quine, W. H. O. (1986): Philosophy of Logic. Second Edition. Harvard University Press. Cambridge, Massachusetts and London, England, 47-61.

The concern of deductive logic is generally viewed as the systematic recognition of logical principles, i.e., of logical truths. This paper presents and analyzes different instantiations of the three main interpretations of logical principles, viz. as ontological principles, as empirical hypotheses, and as true propositions in virtue of meanings. I argue in this paper that logical principles are true propositions in virtue of the meanings of the logical terms within a certain linguistic framework. Since these (...) principles also regulate and control the process of deduction in inquiry, i.e., they are prescriptive for the use of language and thought in inquiry, I argue that logic may, and should, be seen as an instrument or as a way of proceeding (modus procedendi) in inquiry. (shrink)

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. (shrink)

Does general validity or real world validity better represent the intuitive notion of logical truth for sentential modal languages with an actuality connective? In (Philosophical Studies 130:436–459, 2006) I argued in favor of general validity, and I criticized the arguments of Zalta (Journal of Philosophy 85:57–74, 1988) for real world validity. But in Nelson and Zalta (Philosophical Studies 157:153–162, 2012) Michael Nelson and Edward Zalta criticize my arguments and claim to have established the superiority of real world validity. (...) Section 1 of the present paper introduces the problem and sets out the basic issues. In Sect. 2 I consider three of Nelson and Zalta’s arguments and find all of them deficient. In Sect. 3 I note that Nelson and Zalta direct much of their criticism at a phrase (‘true at a world from the point of view of some distinct world as actual’) I used only inessentially in Hanson (Philosophical Studies 130:436–459, 2006), and that their account of the philosophical foundations of modal semantics leaves them ill equipped to account for the plausibility of modal logics weaker than S5. Along the way I make several general suggestions for ways in which philosophical discussions of logical matters–especially, but not limited to, discussions of truth and logical truth for languages containing modal and indexical terms–might be facilitated and made more productive. (shrink)

The paper deals with the question whether logical truth carry information. On the one hand it seems that we gain new information by drawing inferences or arriving at some theorems. On the other hand the formal accounts of information and information content which are most widely known today say that logical truth carry no information at all. The latter is shown by considering these accounts. Then several ways to deal with the dilemma are distinguished, especially syntactic (...) and ontological solutions. A version of a syntactical solution is favoured. (shrink)

Tarski implicitly postulated that a certain pre-theoretical concept of logical consequence and his technical concept of logical consequence are co-extensional. This chapter makes explicit a few theses about logical consequence or logical truth that sound Tarskian somehow, including one that most deserves the name ‘Tarski's Thesis’. Some of these theses are probably true or close to true but weaker than Tarski's. Some are false but stronger than Tarski's. Tarski's Thesis plausibly postulated that a sentence of (...) a classical language possibly extended with non-traditional extensional logical constants is logically true, if it is true in all classical interpretations of all its non-logical constants. But it is noted that this thesis turns out to be false on most conceptions of logical truth, for some sentences of a classical language extended with extensional logical constants are true in all classical interpretations of all its non-logical constants, but are not necessary. (shrink)

In this paper, I ask whether we should see different logical systems as appropriate for different domains (or perhaps in different contexts) and whether this would amount to a form of logical pluralism. One, though not the only, route to this type of position, is via pluralism about truth. Given that truth is central to validity, the commitment the typical truth pluralist has to different notions of truth for different domains may suggest differences regarding (...) validity in those different domains. Indeed, as we’ll see, the differences between the proposed multiple notions of truth are often of a type that is clearly significant in relation to logical features, such as whether or not a constructive notion of truth is at issue. I criticise domain-based logical pluralism. Having done so I introduce a context-based framework that operates with a context-relative notion of validity. I show that this context-based framework can be employed by the domain-specific logical pluralist, but that framework also allows for logical pluralism that does not involve several domains. Different contexts may demand rules of classical logic, where others only justify intuitionistic rules, even when the same domain (e.g. mathematics) is at issue. (shrink)

Danielle Macbeth disagrees with the view that there are logical truths in an ontological sense, and argues that we have no adequate epistemological account of our access to such features of reality. In my response I recall some main aspects of my ontological and epistemological formulation of logic as a science, and argue that neither Quine’s considerations against meaning, nor Benacerraf’s considerations against Gödel’s realism, show the untenability of an approach to logical truth in terms of (...) class='Hi'>logical propositions that denote logical states of affairs.Danielle MacBeth discorda da tese que há verdades lógicas em um sentido ontológico e argumenta que não há um tratamento adequado de nosso acesso epistêmico à tais aspectos da realidade. Em minha réplica relembro algumas características principais de minha formulação ontológica e epistemológica da lógica como ciência, e argumento que nem as considerações de Quine contra a noção de significado, nem as considerações de Benacerraf contra o realismo de Gödel, mostram a invalidade de uma concepção de verdade lógica em termos de proposições que denotam estados de coisa lógicos. (shrink)

In my response to Guillermo Rosado-Haddock I discuss the two main issues raised in his paper. The first is that by allowing Henkin’s general models as a legitimate model-theoretic interpretation of second-order logic, I undermine my defense of second-order logic against Quine’s views concerning the primacy of first-order logic. The second is that my treatment of logical truth and logical properties does not take into account various systems of logic and properties of systems of logic such as (...) the Löwenheim-Skolem property.Em minha réplica à Guillermo Rosado-Haddock discuto as duas questões centrais levantadas em seu artigo. A primeira é que ao permitir modelos gerais de Henkin como uma interpretação legítima da lógica de segunda ordem, desvirtuo minha defesa da lógica de segunda ordem contra a visão de Quine respeito à primazia da lógica de primeira ordem. A segunda é que meu tratamento da verdade lógica e das propriedades lógicas não leva em consideração diversos sistemas de lógica e propriedades de sistemas de lógica tais como a propriedade de Löwenheim-Skolem. (shrink)

This volume is a collection of my essays on philosophy of logic from a phenomenological perspective. They deal with the four kinds of logic I have been concerned with: formal logic, transcendental logic, speculative logic and hermeneutic logic. Of these, only one, the essay on Hegel, touches upon 'speculative logic', and two, those on Heidegger and Konig, are concerned with hermeneutic logic. The rest have to do with Husser! and Kant. I have not tried to show that the four logics (...) are compatible. I believe, they are--once they are given a phenomenological underpinning. The original plan of writing an Introduction in which the issues would have to be formulated, developed and brought together, was abandoned in favor of writing an Introductory Essay on the 'origin'- in the phenomenological sense -of logic. J.N.M. Philadelphia INTRODUCTION: THE ORIGIN OF LOGIC The question of the origin of logic may pertain to historical origin (When did it all begin? Who founded the science of logic?), psychological origin (When, in the course of its mental development, does the child learn logical operations?), cultural origin (What cultural - theological, metaphysical and linguisti- conditions make such a discipline as logic possible?), or transcendental constitutive origin (What sorts of acts and/or practices make logic possible?). (shrink)

In this paper, I consider the criticism due to Hartry Field, John Pollack, William Hanson and James Hawthorne that the Kripkean requirement that a logical truth in modal logic be true at all possible worlds in _all quantified model structures is unmotivated and misses some logical truths. These authors do not see the basis for making the logical truth of a modal sentence turn on more than the model structure given by one reading of the (...) modal operator(s) which occur in the sentence. The primary goal here is to motivate the Kripkean requirement. (shrink)

W. V. Quine thinks logical truth can be defined in purely extensional terms, as follows: a logical truth is a true sentence that exemplifies a logical form all of whose instances are true. P. F. Strawson objects that one cannot say what it is for a particular use of a sentence to exemplify a logical form without appealing to intensional notions, and hence that Quine's efforts to define logical truth in purely extensional (...) terms cannot succeed. Quine's reply to this criticism is confused in ways that have not yet been noticed in the literature. This may seem to favour Strawson's side of the debate. In fact, however, a proper analysis of the difficulties that Quine's reply faces suggests a new way to clarify and defend the view that logical truth can be defined in purely extensional terms. (shrink)

Thirty-two years ago W. V. Quine proposed a definition of 'logical truth' that has been widely repeated and reprinted. Quine himself seems to have recognized that this definition is wrong in detail; in section 1 we eliminate this fault. What has perhaps been less widely observed is that, in abandoning the model-theoretic account of logical truth in favor of a "substitutional" account, Quine's definition swells the ranks of the logical truths and makes the classification of (...) a sentence as a logical truth dependent both on the interpretation of its extralogical words and on the extralogical vocabulary available in the language. (shrink)

Classical logic counts sentences such as ‘Alice is identical with Alice’ as logically true. A standard objection to classical logic is that Alice’s self-identity, for instance, is not a matter of logic because the identity of particular objects is not a matter of logic. For this reason, many philosophers argue that classical logic is not the right logic, and that it should be abandoned in favour of free logic — logic free of existential commitments with respect to singular terms. In (...) most standard free logics, sentences such as ‘Alice is identical with Alice’ are not logically true. This paper argues that this objection from existential commitments is some- what superficial and that there is a deeper reason why ‘Alice is identical with Alice’ should not be considered a logical truth. Indeed, a key fundamental thought about the nature of logic is that a logical truth is true in virtue of its logical form. The fundamental problem I raise is that a sentence such as ‘Alice is identical with Alice’ appears to not even be true in virtue of its logical form. Thus this paper argues that given that such a sentence is not true in virtue of its logical form, it should not be counted as logically true. It moreover argues, on the same grounds, that even the sentences which free logicians regard as logically true shouldn’t be regarded as logically true. So in this sense free logic is no repair to classical logic. (shrink)

In the paper (Braüner, 2001) we gave a minimal condition for the existence of a homophonic theory of truth for a modal or tense logic. In the present paper we generalise this result to arbitrary modal logics and we also show that a modal logic permits the existence of a homophonic theory of truth if and only if it permits the definition of a socalled master modality. Moreover, we explore a connection between the master modality and hybrid logic: (...) We show that if attention is restricted to bidirectional frames, then the expressive power of the master modality is exactly what is needed to translate the bounded fragment of first-order logic into hybrid logic in a truth preserving way. We believe that this throws new light on Arthur Prior's fourth grade tense logic. (shrink)

Some remarks on determination, physicalism, model theory, and logical truth.//An attempt to defend physicalism against objections that its bases are indeterminate.

Anti-realism is a doctrine about logic, language, and meaning that is based on the work of Wittgenstein and Frege. In this book, Professor Tennant clarifies and develops Dummett's arguments for anti-realism and ultimately advocates a radical reform of our logical practices.

On the model-theoretic account, a sentence is logically true just in case it is true on all possible semantic interpretations. We dierentiate four ways one can interpret the modality 'possible' in this definition, and argue that one of these readings is not subject to the criticism levelled against the model-theoretic account by Etchemendy. By explicating the four readings we also draw some consequences for what linguistic evidence a selection of logical theories should be sensitive to.

This fourth and final volume of writings by Elizabeth Anscombe reprints her _ Introduction to Wittgenstein's Tractatus_, together with a number of later essays on thought and language in which she explores issues of reason, representation, truth and existence. As with previous volumes this gathers hitherto inaccessible publications and previously unpublished texts. Singly and collectively the four volumes provide for a broader and deeper understanding of the thought of one of the twentieth century's most important anglophone philosophers.

We shall be concerned with the modal logic BK—which is based on the Belnap–Dunn four-valued matrix, and can be viewed as being obtained from the least normal modal logic K by adding ‘strong negation’. Though all four values ‘truth’, ‘falsity’, ‘neither’ and ‘both’ are employed in its Kripke semantics, only the first two are expressible as terms. We show that expanding the original language of BK to include constants for ‘neither’ or/and ‘both’ leads to quite unexpected results. To be (...) more precise, adding one of these constants has the effect of eliminating the respective value at the level of BK-extensions. In particular, if one adds both of these, then the corresponding lattice of extensions turns out to be isomorphic to that of ordinary normal modal logics. (shrink)

Gottlob Frege takes logic to be the science of truth throughout his career. However, the mature Frege makes remarks which seem to go against the idea that logic is the science of truth. This paper shows that we can explain away this tension in the mature Frege’s conception of logic if we accept that truth is an object, that is, the truth-vale True qua the reference of a sentence, for Frege. Even though the main thesis of (...) this paper is a conditional, I provide reasons why we ought to consider the possibility seriously that truth is an object for Frege. I also explain how we can make sense of Frege’s conception of logic as the science of truth while accepting truth is an object. (shrink)

I came to the topic of the title in connection with my logical investigations of the Is-Ought problem in multimodal logics . There are infinitely many mathematically possible modal logics. Are they all philosophically serious candidates? Which modal logic the “right” one — does such a question make sense? A similar question can be raised for the infinite variety of propositional logics weaker than classical logics. The Vienna Circle concept of logic was that logic holds merely by form, independently (...) from the facts of the world. Have we lost this concept completely? Is it a matter of arbitrary choice, of mere subjective-practical appropriateness, which logic one chooses? Is Quine right that there is no distinction between analytic and synthetic truth, even if we take “analytic truth” in the narrow sense of “logical truth”? These are the questions which have motivated this paper. (shrink)

A formula is a contingent logical truth when it is true in every model M but, for some model M , false at some world of M . We argue that there are such truths, given the logic of actuality. Our argument turns on defending Tarski’s definition of truth and logical truth, extended so as to apply to modal languages with an actuality operator. We argue that this extension is the philosophically proper account of validity. (...) We counter recent arguments to the contrary presented in Hanson’s ‘Actuality, Necessity, and Logical Truth’ (Philos Stud 130:437–459, 2006 ). (shrink)

Kant's question 'How are synthetic judgments a priori possible?' pre- cipitated the Critique of Pure Reason. Question and answer notwith- standing, Mill and others persisted in doubting that such judgments were possible at all. At length some of Kant's own clearest purported.

Anti-realistic conceptions of truth and falsity are usually epistemic or inferentialist. Truth is regarded as knowability, or provability, or warranted assertability, and the falsity of a statement or formula is identified with the truth of its negation. In this paper, a non-inferentialist but nevertheless anti-realistic conception of logical truth and falsity is developed. According to this conception, a formula (or a declarative sentence) A is logically true if and only if no matter what is told (...) about what is told about the truth or falsity of atomic sentences, A always receives the top-element of a certain partial order on non-ontic semantic values as its value. The ordering in question is a told-true order. Analogously, a formula A is logically false just in case no matter what is told about what is told about the truth or falsity of atomic sentences, A always receives the top-element of a certain told-false order as its value. Here, truth and falsity are pari passu , and it is the treatment of truth and falsity as independent of each other that leads to an informational interpretation of these notions in terms of a certain kind of higher-level information. (shrink)

I provide a motivation for Wittgenstein's holding to the view that a necessary condition of an item's possessing a sense is its being capable of truth and capable of falsehood. I argue that Wittgenstein adopted the relevant view in order to defend an approach to the determination of logical truth on which the subject matter of a proposition is irrelevant to our making such a determination. This approach was itself conceived of as a remedy to that employed (...) by Russell, and to a conception of logical truth on which the axiom of reducibility counts as logically true. (shrink)

Shapiro and Taschek have argued that simply using intuitionistic logic and its Heyting semantics, one can show that there are no gaps in warranted assertability. That is, given that a discourse is faithfully modeled using Heyting's semantics for the logical constants, then if a statement _S is not warrantedly assertable, its negation (superscript box) _S is. Tennant has argued for this conclusion on similar grounds. I show that these arguments fail, albeit in illuminating ways. An appeal to constructive logic (...) does not commit one to this strong epistemological thesis, but appeals to semantics of intuitionistic logic none the less do give us certain conclusions about the connections between warranted assertability and truth. (edited). (shrink)

by Mark Weinstein King’s College London, UK: College Publications, 2013. Pp. viii, 1-232. Softcover. ISBN-13: 978-1-84890-100-1, ISBN-10: 1848901003. US$ 17.00.

In the first part of this paper, I express doubts that Tarski and Carnap were guilty of some confusions about the relations between truth and meaning, attributed to them by Soames. In the second part, I consider Quine's Carrollian argument against conventionalism about logical truth, discussed only briefly and approvingly by Soames, and I explore the question whether some not obviously incorrect forms of conventionalism about logical truth, such as what I call "finitary conventionalism", are (...) immune to Quine's argument. (shrink)

Starting from certain metalogical results, I argue that first-order logical truths of classical logic are a priori and necessary. Afterwards, I formulate two arguments for the idea that first-order logical truths are also analytic, namely, I first argue that there is a conceptual connection between aprioricity, necessity, and analyticity, such that aprioricity together with necessity entails analyticity; then, I argue that the structure of natural deduction systems for FOL displays the analyticity of its truths. Consequently, each philosophical approach (...) to these truths should account for this evidence, i.e., that first-order logical truths are a priori, necessary, and analytic, and it is my contention that the semantic account is a better candidate. (shrink)

According to a traditional view all logical truths are necessary however, this thesis recently has been faced with various critiques from different points of view. Introducing some logical operators, David Kaplan and Edward Zalta claim that there are logical truths regarding common definition ‒ that are not necessary. William Hanson objects Zalta's examples believing that they rely on unjustified presuppositions especially he does not accept real world validity as a proper notion for presenting logical truth. (...) Nelson and Zalta reply to his objections claiming that they have unacceptable grounds. In this paper, we introduce logical truths, then present Kaplan's and Zalta's examples and explore Hanson's objections together with their replies. At last we try to show the metaphysical roots of the debates. (shrink)

Finitely algebraizable deductive systems were introduced by Blok and Pigozzi to capture the essential properties of those deductive systems that are very tightly connected to quasivarieties of universal algebras. They include the equivalential logics of Czelakowski. Based on Blok and Pigozzi’s work, Herrmann defined algebraizable deductive systems. These are the equivalential deductive systems that are also truth-equational, in the sense that the truth predicate of the class of their reduced matrix models is explicitly definable by some set of (...) unary equations. Raftery undertook the task of characterizing the property of truth-equationality for arbitrary deductive systems. In this paper, following Raftery, we extend the notion of truth-equationality for logics formalized as $\pi$-institutions and abstract several of the results that hold for deductive systems in this more general categorical context. (shrink)

The aim of this paper is to show what sorts of logics are required by externalist and internalist accounts of the meanings of natural kind nouns. These logics give us a new perspective from which to evaluate the respective positions in the externalist-internalist debate about the meanings of such nouns. The two main claims of the paper are the following: first, that adequate logics for internalism and externalism about natural kind nouns are second-order logics; second, that an internalist second-order logic (...) is a free logic—a second order logic free of existential commitments for natural kind nouns, while an externalist second-order logic is not free of existential commitments for natural kind nouns—it is existentially committed. (shrink)

It is a consequence of Quine’s confirmation holism that the logical laws are in principle revisable. Some have worried this is at odds with another dictum in Quine, viz., that any translation which construes speakers as systematically illogical is ipso facto inadequate. In this paper, I try to formulate exactly what the problem is here, and offer a solution to it by (1) disambiguating the term ‘logic,’ and (2) appealing to a Quinean understanding of ‘necessity.’ The result is that (...) the different theses in Quine’s philosophy of logic are to be situated within different contexts of inquiry. (shrink)

I expose a tension in Bertrand Russell's, _Introduction to Mathematical Philosophy, between his account of logical truth and his view that logical truth is knowable without taking into account what the world is like. Russell makes the logical truth of a sentence turn on the actual truth of its second-order universal closure. But this results in making logical truth relative to the number of worldly individuals. I aim to use the tension (...) in _Introduction to Mathematical Philosophy to classify the status of the model-theoretic account as an analysis of the modal notions in classical logic. (shrink)

Gary Kemp: Quine's Relationship with Analytic Philosophy: I try to explain why Quine, for all his fame amongst analytic philosophers, has so few explicit followers within analytic philosophy of the past fifty years – despite the fact that naturalism, at least as broadly conceived, is so popular. Partly it's because Quine's particular version of naturalism is so demanding, partly it's because the nature and seriousness of his commitment to extensionalism are not well recognized, and partly because his views were formulated (...) from an extremely general and abstract point of view in the philosophy of science. I focus on the second and especially on the third. Quine is more radical and more alien than is customarily appreciated. (shrink)

In this short paper I am concerned with basically two especially important issues in Oswaldo Chateaubriand’s Logical Forms II; namely, the dispute between first- and higher-order logic and his conception of logical truth and related notions, like logical property, logical state of affairs and logical falsehood. The first issue was also present in the first volume of the book, but the last is privative of the second volume. The extraordinary significance of both issues for (...) philosophy is emphasized and, though there is a basic agreement with Chateaubriand’s views, some critical remarks are interspersed.Neste pequeno artigo considero basicamente duas questões particularmente importantes em Logical Forms II de Oswaldo Chateaubriand; a saber, a disputa entre a lógica de primeira e de segunda ordem e sua concepção de verdade lógica e noções relacionadas, como as de propriedade lógica, estado de coisas lógico e falsidade lógica. A primeira questão também estava presente no primeiro volume do livro, mas a última apenas aparece no segundo volume. Enfatizo o significado extraordinário de ambas as questões para a filosofia e, embora haja uma concordância básica com as visões de Chateaubriand, algumas observações críticas são inseridas. (shrink)

An earlier article by the author, "quine and strawson on logical theory" ("analysis" volume 34, pages 207-208), is expanded and defended against criticisms made by charles sayward in "the province of logic" ("analysis" volume 36, pages 47-48). it is shown that quine's definition of logical truth presupposes an understanding of "possibility," even if the term 'sentence' is used set-theoretically, and that if quine is allowed the concept of "possibility," then strawson must be allowed modal concepts for his (...) purposes. the traditional claim that an argument is valid if and only if the corresponding conditional is necessary is also defended. (shrink)

Quine claims that the analytic-synthetic distinction lacks a proper characterization of a notion to be used to reduce analytic statements "depending upon essential predication" to logically true statements. the author shows that the same arguments used by quine against analyticity can also be used against logical truth; if one notion is "given up", the other must be also. notions such as "filling blanks alike" and "identical propositions" presupposed by logical truth have the same deficiencies as does (...) analyticity. logical truth is not more basic than analyticity; the two notions stand or fall together. (shrink)

This paper analyzes the logical truths as (very roughly) those truths that would still have been true under a certain range of counterfactual perturbations.What’s nice is that the relevant range is characterized without relying (overtly, at least) upon the notion of logical truth. This approach suggests a conception of necessity that explains what the different varieties of necessity (logical, physical, etc.) have in common, in virtue of which they are all varieties of necessity. However, this approach (...) places the counterfactual conditionals in an unfamiliar foundational role. (shrink)