There have been few attempts to answer the challenges for alethic pluralists to maintain standard accounts of the logical operators and of logical consequence in a sufficiently systematic and precise way. This chapter presents a pluralist account of logic and semantics that answers these challenges. The chapter also shows how to accommodate logical pluralism and ontological pluralism within an extension of the framework.

Differences among scientific, mathematical, and ethical subject matters motivate a pluralism where distinct domains of subject matter are associated with distinct truth properties and logics. However, it is unclear how such pluralism might accommodate potentially attractive epistemic norms, such as that one ought to believe only what is true, and that one ought to believe what is logically true. In this paper, I show how such pluralism can accommodate such norms by supplementing the account developed in Yu (2017a,b) with (...) epistemic, doxastic, and deontic operators. The upshot is that pluralism is compatible with, even if not committed to, monism about epistemic norms. (shrink)

This chapter contains sections titled: Introduction Mixed Inferences and Mixed Compounds Alethic Pluralism as Functionalism More than One Logic? Conclusion.

There have been few attempts to answer the twin challenges for alethic pluralists to maintain standard accounts of the logical operators and of logical consequence in a sufficiently systematic and precise way. In this paper, I propose an account of logic and semantics on behalf of pluralists that answers both challenges in a sufficiently systematic and precise way. Crucially, the account accommodates mixed atomics, and its first-order extension also accommodates quantified sentences. Accordingly, pluralists can answer all the distinctively logical (...) challenges for their view. (shrink)

Alethic pluralism holds that there are many ways of being true. The view has been accused of being unable to do justice to the traditional account of logical validity, understood as necessary truth preservation. In this paper I reformulate the debate in terms of the naturalness of generic truth, and discuss some notable consequences of this more careful reformulation. I show not only that some alleged solutions, like the resort to plural quantification, are ineffective, but also that the problem (...) is not really posed by mixed inferences, as usually thought. Finally, I argue that the traditional account of logical validity does carry a commitment to generic truth, so that a strong version of alethic pluralism can hardly vindicate it. (shrink)

It has been argued that alethic pluralists -- who hold that there are several distinct truth properties -- face a problem when it comes to defining validity. Via consideration of the classical concept of logical consequence, and of strategies for defining validity in many-valued logics, this paper proposes two new kinds of solution to the problem.

The purpose of this work is to provide an answer to two fundamental questions: 1) Can a non-alethic logic be a Meinongian logic? And consequently 2) Can a non-alethic logic be an adequate logic for a Meinongian theory of objects? Using the results of da Costa and da Costa & Marconi and furthermore of da Costa I propose a minimal non-alethic logic of the first order with identity and Hilbert’s "-symbol which can bring into Meinongian spirit the (...) most relevant aspects of Meinongian logic underlying Meinong’s theory of objects. This is just a first approach of mine, to account for a complex thought, but so interesting, too as Meinong’s thought. Furthermore, giving a positive answer to 1) and 2) I indicate a plausible way which can avoid both difficult approaches and the attempt to refuse the theory of objects in order to do not compromise standard logic and some of its own laws. My approach shows that Meinong’s theory can be a valid ontology, because there is adequate and not banal logic underlying it. • DOI:10.5007/1808-1711.2010v14n1p99. (shrink)

The purpose of this paper is to describe a set of temporal alethic–deontic systems, i.e. systems that include temporal, alethic and deontic operators. All in all we will consider 2,147,483,648 systems. All systems are described both semantically and proof theoretically. We use a kind of possible world semantics, inspired by the so-called T x W semantics, to characterize our systems semantically and semantic tableaux to characterize them proof theoretically. We also show that all systems are sound and complete (...) with respect to their semantics. (shrink)

In my paper 'Validity in Simple Partial Logic'(2002) I made comparison between several definitions of validity in Simple Partial Logic(SPL) and adopted two of them as most appropriate. In this paper, after elaborating more on these two definitions than in my previous paper and considering the characteristics of Partial Semantics, in which these definitions are given, I construct a tableau proof system and prove its soundness and completeness. Then, based on the characterization of Partial Semantics, I will show that we (...) can regard SPL as a logic of extensional alethic modality. (shrink)

This chapter contains sections titled: Introduction Modal propositional Logics (MPLs) Modal Quantificational Logics(QMLs).

A contrary-to-duty obligation (sometimes called a reparational duty) is a conditional obligation where the condition is forbidden, e.g. “if you have hurt your friend, you should apologise”, “if he is guilty, he should confess”, and “if she will not keep her promise to you, she ought to call you”. It has proven very difficult to find plausible formalisations of such obligations in most deontic systems. In this paper, we will introduce and explore a set of temporal alethic dyadic deontic (...) systems, i.e., systems that include temporal, alethic and dyadic deontic operators. We will then show how it is possible to use our formal apparatus to symbolise contrary-to-duty obligations and to solve the so-called contrary-to-duty (obligation) paradox, a problem well known in deontic logic. We will argue that this response to the puzzle has many attractive features. Semantic tableaux are used to characterise our systems proof theoretically and a kind of possible world semantics, inspired by the so-called T× W semantics, to characterise them semantically. Our models contain several different accessibility relations and a preference relation between possible worlds, which are used in the definitions of the truth conditions for the various operators. Soundness results are obtained for every tableau system and completeness results for a subclass of them. (shrink)

According to strong pluralist theories of truth, ‘true’ designates different properties depending on which sentences it’s applied to. An influential objection to strong pluralism claims it can’t make sense of logically complex sentences whose components have different truth-properties. For example, if ‘true’ designates correspondents for ‘Tabby is a cat’, and it designates coherence for ‘Tabby is beautiful’, what does it designate for ‘Tabby is a beautiful cat’ (Tappolet 1997)? Will Gamester (2019) has proposed a novel pluralist theory meant to avoid (...) the problem. The theory construes ‘true’ as designating a different property for each possible logical structure, and he has challenged monists to identify shortcomings of the theory in virtue of its pluralism. This paper answers Gamester’s challenge and identifies three such shortcomings. (1) The theory can’t make sense of the idea that all true conjunctions share the property of having true conjuncts, in virtue of which they are true. (2) The theory imposes unmotivated syntactic constraints on the language in which the theory of truth is formulated. (3) Avoiding the second shortcoming requires arbitrary choices among equally good candidates for “the” logical form of sentences and hence the designation of ‘true’ as applied to them. (shrink)

In this contribution I will examine Cotnoir’s (2013) solution to the problems that alethic pluralism faces when it comes to logical paradoxes. I will argue that his proposal fails to be a viable option and I will put forward an alternative approach, more Tarskian in spirit, but with the same “pluralist” trait of Cotnoir’s solution. Such an alternative approach is based on the idea that each truth predicate can be associated with an index that fully describes its relation with (...) other truth predicates.I will show how such indexes must be constrained in order to avoid logical paradoxes. (shrink)

O propósito deste trabalho é fornecer uma resposta a duas questões fundamentais: 1) pode uma lógica não alética ser uma lógica meinongiana? E consequentemente 2) pode uma lógica não alética ser uma lógica adequada a uma teoria meinongiana dos objetos? Usando os resultados de da Costa (1989) e da Costa & Marconi (1986) e além disso de da Costa (1986 e 1993), proponho uma lógica minimal não alética de primeira ordem com identidade e o símblo " de Hilbert (da Costa (...) et al. 1992) que podem colocar em um espírito meinongiano os aspectos mais relevantes da lógica meinongiana subajcente à teoria dos objetos de Meinong. Esta é apenas uma primeira abordagem minha, para dar conta de reflexões complexas, mas também interessante como o pensamento de Meinong. Além disso, dando uma resposta positiva a 1) e 2) indico um modo plausível que pode evitar ambas as difíceis abordagens e a tentativa de recusar a teoria dos objetos de modo a não comprometer a lógica padrão e algumas de suas leis. Minha abordagem mostra que a teoria de Meinong pode ser uma ontologia válida, porque há uma lógica adequada e não banal subjacente a ela. DOI:10.5007/1808-1711.2010v14n1p99. (shrink)

The paper develops a set of quantified temporal alethic boulesic doxastic systems. Every system in this set consists of five parts: a ‘quantified’ part, a temporal part, a modal (alethic) part, a boulesic part and a doxastic part. There are no systems in the literature that combine all of these branches of logic. Hence, all systems in this paper are new. Every system is defined both semantically and proof-theoretically. The semantic apparatus consists of a kind of$$T \times W$$T×Wmodels, (...) and the proof-theoretical apparatus of semantic tableaux. The ‘quantified part’ of the systems includes relational predicates and the identity symbol. The quantifiers are, in effect, a kind of possibilist quantifiers that vary over every object in the domain. The tableaux rules are classical. The alethic part contains two types of modal operators for absolute and historical necessity and possibility. According to ‘boulesic logic’ (the logic of the will), ‘willing’ (‘consenting’, ‘rejecting’, ‘indifference’ and ‘non-indifference’) is a kind of modal operator. Doxastic logic is the logic of beliefs; it treats ‘believing’ (and ‘conceiving’) as a kind of modal operator. I will explore some possible relationships between these different parts, and investigate some principles that include more than one type of logical expression. I will show that every tableau system in the paper is sound and complete with respect to its semantics. Finally, I consider an example of a valid argument and an example of an invalid sentence. I show how one can use semantic tableaux to establish validity and invalidity and read off countermodels. These examples illustrate the philosophical usefulness of the systems that are introduced in this paper. (shrink)

The purpose of this paper is to describe a set of quantified temporal alethic-deontic systems, i.e., systems that combine temporal alethicdeontic logic with predicate logic. We consider three basic kinds of systems: constant, variable and constant and variable domain systems. These systems can be augmented by either necessary or contingent identity, and every system that includes identity can be combined with descriptors. All logics are described both semantically and proof theoretically. We use a kind of possible world semantics, (...) inspired by the so-called T × W semantics, to characterize them semantically and semantic tableaux to characterize them proof theoretically. We also show that all systems are sound and complete with respect to their semantics. (shrink)

The paper argues against a commitment to metaphysical necessity, semantic modalities are enough. The best approaches to elucidate the semantic modalities are (still) versions of lingustic ersatzism and fictionalism, even if only developed in parts. Within these necessary properties and the difference between natural and semantic laws can be accounted for. The proper background theory for this is an updated version of Logical Empiricism, which is congenial to recent trends in Structural Realism. The anti-metaphysical attitude of Logical Empiricism deserves revitalization. (...) Another target besides metaphysical necessity are substantial forms of iterated modalities, as used, for instance, in the philosophy of religion. (shrink)

This chapter contains sections titled: Introduction Model Theory Proof Theory Modal Predicate Logic.

The non-alethic systems N1 of da Costa and A of Grana are both paraconsistent and paracomplete. Based on them, a multi-agent doxastic logic NADK can be obtained by logical expansion. The soundness and completeness of NADK are proved and its special theorems are also presented. In this logic, the belief version of the laws of contradiction and excluded middle, as well as the principle of explosion are all invalid. Therefore, it may provide a reliable logical basis for any theory (...) which has paraconsistent or paracomplete epistemic conflicts, such as true contradictions, true contrarieties, and belief paradoxes. We also explain in detail how a non-alethic doxastic logic provides a reliable logical basis for tolerating these three types of epistemic conflicts. The present paper is the deepening and development of system N1 and A. (shrink)

This chapter contains sections titled: Introduction Intensions Models About Quantification Truth in Models Equality Rigidity De Re/De Dicto Partial Designation Designation and Existence Definite Descriptions What Next?

This paper will introduce and explore a set of quantified counterfactual temporal alethic-deontic systems, that is, systems that combine counterfactual temporal alethic-deontic logic with predicate logic. I will consider three types of systems: constant, variable and constant and variable domain systems. Every system can be combined with either necessary or contingent identity. All logics are described both semantically and proof theoretically. I use a kind of possible world semantics, inspired by the so-called T x W semantics, to (...) characterise them semantically and semantic tableaux to characterise them proof theoretically. Our models contain several different accessibility relations and a similarity relation between possible worlds, which are used in the definitions of the truth conditions for the various operators. Soundness results are obtained for every tableau system and completeness results for a subclass of these. (shrink)

The challenge for alethic pluralists to maintain a standard, truth-functional account of the logical operators has received some attention. In this paper, I consider a related but more fundamental challenge, to maintain a compositional account of the logical operators, which has received much less attention. I argue that, given natural assumptions, pluralists cannot answer this challenge.

One of the most important “folk” anti-realist thoughts about certain areas of our thought and discourse—basic taste, for instance, or comedy—is that their lack of objectivity crystallises in the possibility of “faultless disagreements”: situations where one party accepts P, another rejects P, and neither is guilty of any kind of mistake of substance or shortcoming of cognitive process. On close inspection, however, it proves challenging to make coherent sense of this idea, and a majority of theorists have come to reject (...) it as incoherent. There are two significant exceptions in the contemporary literature: relativists often hold it up as something of a coup for their view that it can make straightforward sense of faultless disagreement; and the author of this paper has argued (Wright 2006) that making judicious intuitionistic revisions to classical logic can provide resources that suffice to stabilise the notion. The present paper argues that neither relativism nor intuitionism in fact provides a satisfactory account and indicates how an alethic pluralist framework enables us to do better. (shrink)

According to alethic functionalism, truth is a higher-order multiply realizable property of propositions. After briefly presenting the views main principles and motivations, I defend alethic functionalism from recent criticisms raised against it by Cory Wright. Wright argues that alethic functionalism will collapse either into deflationism or into a view that takes true as simply ambiguous. I reject both claims.

Some philosophers have argued that truth is a norm of judgement and have provided a variety of formulations of this general thesis. In this paper, I shall side with these philosophers and assume that truth is a norm of judgement. What I am primarily interested in here are two core questions concerning the judgement-truth norm: (i) what are the normative relationships between truth and judgement? And (ii) do these relationships vary or are they constant? I argue for a pluralist picture—what (...) I call Normative Alethic Pluralism (NAP)—according to which (i) there is more than one correct judgement-truth norm and (ii) the normative relationships between truth and judgement vary in relation to the subject matter of the judgement. By means of a comparative analysis of disagreement in three areas of the evaluative domain—refined aesthetics, basic taste and morality—I show that there is an important variability in the normative significance of disagreement—I call this the variability conjecture. By presenting a variation of Lynch’s scope problem for alethic monism, I argue that a monistic approach to the normative function of truth is unable to vindicate the conjecture. I then argue that normative alethic pluralism provides us with a promising model to account for it. (shrink)

I have two objectives in this paper. The first is to investigate whether, and to what extent, truth is valuable. I do this by first isolating the value question from other normative questions. Second, I import into the debate about the nature of truth some key distinctions hailing from value theory. This will help us to clarify the sense in which truth is valuable. I then argue that there is significant variability in the value of truth in different areas of (...) discourse. I shall call this the axiological variability conjecture. I illustrate and substantiate AVC by contrasting the occurrence of disagreement in two paradigmatically evaluative areas of discourse, viz. matters of taste, on the one hand, and morality, on the other. I claim that there is a reasonable tendency to care much more about settling moral disagreements than taste disagreements and that this difference has to do, at least partly but significantly, with the different value that truth exhibits in these two areas of discourse. I then turn to the second objective of the paper—namely, to discuss how pluralistic accounts of the nature of truth may deal with the value of truth in light of AVC. I will argue that AVC is a problem for all versions of truth pluralism that are committed to the following two theses: that truth is a value concept; and that this characteristic of the concept has to be reflected in the metaphysical nature of any admissible truth properties—i.e., all the various properties that are admissible in the pluralist account are value-conferring properties and thus intrinsically valuable. In so doing, I will focus primarily on Michael Lynch’s functionalist incarnation of truth pluralism. Lynch terms this “Manifestation Alethic Pluralism”. My reason for this is twofold: first and foremost, MAP is a paradigmatic exemplification of a model of truth pluralism that is committed to both and ; second, MAP has, to date, enjoyed the most discussion, and currently provides the most developed account of truth pluralism. However, I argue that MAP lacks the resources to account for AVC. Owing to this, I suggest two ways out for an advocate of MAP, which force various structural changes in her view. (shrink)

According to the standard view, alethic (or modal) statements are intensional in that the Principle of Substitution (PS) fails for them -- e.g. substituting 'nine' in "Necessarily, nine is composite" with the co-referring 'the number of planets' turns this statement from true to false. It is argued in the paper that we could avoid ascribing intensionality to alethic statements altogether by separating between singular and functional uses of definite descriptions: on the singular use the description given above amounts (...) to 'the actual number of planets', which is salva veritate substitutable to 'nine' in all alethic statements; on the functional use, in turn, that description is really a function from possible worlds to numbers, and thus the Principle of Substitution is not violated in this case either, since such a function cannot be held to be co-referential with 'nine'. (shrink)

Stephen Barker presents a novel approach to solving semantic paradoxes, including the Liar and its variants and Curry’s paradox. His approach is based around the concept of alethic undecidability. His approach, if successful, renders futile all attempts to assign semantic properties to the paradoxical sentences, whilst leaving classical logic fully intact. And, according to Barker, even the T-scheme remains valid, for validity is not undermined by undecidable instances. Barker’s approach is innovative and worthy of further consideration, particularly by those (...) of us who aim to find a solution without logical revisionism. As it stands, however, the approach is unsuccessful, as I shall demonstrate below. (shrink)

This paper shows that the Dawson technique of modelling deontic logics into alethic modal logics to gain insight into deontic formulas is not available for modelling a normal (in the spirit of Anderson) relevance deontic modal logic into either of the normal relevance alethic modal logics R S4or R M. The technique is to construct an extension of the well known entailment matrix set M 0and show that the model of the deontic formula P (A (...) v B). PA v PB is excluded. (shrink)

Alethic pluralists often claim that accommodating certain alethic platitudes motivates rejecting deflationism in favour of a pluralist inflationism about truth. Deflationists claim that the logical role of the truth predicate, viz providing something equivalent to variables for sentence-in-use positions and quantifiers governing them, is sufficient to account for the appeal to truth in the alethic platitudes. Surprisingly, however, most deflationists face an insufficiently acknowledged problem with respect to explaining how this mode of generalizing works. The standard substitutional (...) or higher-order interpretations of sentential quantifiers and variables do not meet two desiderata that we claim any adequate account of them must satisfy. To address this issue, we review and extend A. N. Prior's adverbial understanding of sentential quantification, explain how it satisfies the desiderata, and respond to some objections. This shows that deflationists can accommodate and account for the alethic platitudes by applying this non-nominal understanding of generalizing on sentence positions. (shrink)

Thinking about truth can be more dangerous than it looks. Of course, our concept of truth is the source of one of the most frustrating and impenetrable paradoxes humans have ever contemplated, the liar paradox, but that is just the beginning of its treachery. In an effort to understand why one of the most beloved and revered members of our conceptual repertoire could cause us so much trouble, philosophers have for centuries proposed “solutions” to the liar paradox. However, it seems (...) that our concept of truth takes offense to our efforts to understand it because it appears to retaliate against those who propose “solutions” to the liar. It takes its revenge on us by creating new paradoxes from our own attempts to find resolution. That is, most proposed solutions to the liar paradox give rise to new, more insidious paradoxes—often called revenge paradoxes. For our attempts at understanding, truth rewards us with inconsistent theories, untenable logics, and a deep feeling of bewilderment. It is as if our concept of truth lashes out at us because it wants to remain a mystery. After a few run-ins with truth, many philosophers have the good sense to keep their distance. Far from being the serene, profound concept most people take it to be, those of us who think much about the liar paradox know truth to be a vengeful bully—a conceptual misanthrope. (shrink)

I put forward precise and appealing notions of reference, self-reference, and well-foundedness for sentences of the language of first-order Peano arithmetic extended with a truth predicate. These notions are intended to play a central role in the study of the reference patterns that underlie expressions leading to semantic paradox and, thus, in the construction of philosophically well-motivated semantic theories of truth.

I use the principle of truth-maker maximalism to provide a new solution to the semantic paradoxes. According to the solution, AUS, its undecidable whether paradoxical sentences are grounded or ungrounded. From this it follows that their alethic status is undecidable. We cannot assert, in principle, whether paradoxical sentences are true, false, either true or false, neither true nor false, both true and false, and so on. AUS involves no ad hoc modification of logic, denial of the T-schema's validity, or (...) obvious revenge. (shrink)