First-order formalisations are often preferred to propositional ones because they are thought to underwrite the validity of more arguments. We compare and contrast the ability of some well-known logics—these two in particular—to formally capture valid and invalid arguments. We show that there is a precise and important sense in which first-order logic does not improve on propositional logic in this respect. We also prove some generalisations and related results of philosophical interest. The rest of the article investigates the results’ philosophical (...) significance. A first moral is that the correct way to state the oft-cited superiority of first-order logic vis-`a-vis propositional logic is more nuanced than often thought. The second moral concerns semantic theory; the third logic’s use as a tool for discovery. A fourth and final moral is that second-order logic’s transcendence of first-order logic is greater than first-order logic’s transcendence of propositional logic. (shrink)

General-elimination harmony articulates Gentzen’s idea that the elimination-rules are justified if they infer from an assertion no more than can already be inferred from the grounds for making it. Dummett described the rules as not only harmonious but stable if the E-rules allow one to infer no more and no less than the I-rules justify. Pfenning and Davies call the rules locally complete if the E-rules are strong enough to allow one to infer the original judgement. A method is given (...) of generating harmonious general-elimination rules from a collection of I-rules. We show that the general-elimination rules satisfy Pfenning and Davies’ test for local completeness, but question whether that is enough to show that they are stable. Alternative conditions for stability are considered, including equivalence between the introduction- and elimination-meanings of a connective, and recovery of the grounds for assertion, finally generalizing the notion of local completeness to capture Dummett’s notion of stability satisfactorily. We show that the general-elimination rules meet the last of these conditions, and so are indeed not only harmonious but also stable. (shrink)

Frege's philosophical writings, including the “logistic project,” acquire a new insight by being confronted with Kant's criticism and Wittgenstein's logical and grammatical investigations. Between these two points a non-formalist history of logic is just taking shape, a history emphasizing the Greek and Kantian inheritance and its aftermath. It allows us to understand the radical change in rationality introduced by Gottlob Frege's syntax. This syntax put an end to Greek categorization and opened the way to the multiplicity of expressions producing their (...) own intelligibility. This article is based on more technical analyses of Frege which Claude Imbert has previously offered in other writings. (shrink)

Saul Kripke's thesis that ordinary proper names are rigid designators is supported by widely shared intuitions about the occurrence of names in ordinary modal contexts. By those intuitions names are scopeless with respect to the modal expressions. That is, sentences in a pair like (a) Aristotle might have been fond of dogs, (b) Concerning Aristotle, it is true that he might have been fond of dogs will have the same truth value. The same does not in general hold for definite (...) descriptions. If one, like Kripke, accounts for this difference by means of the intensions of the names and the descriptions, the conclusion is that names do not in general have the same intension as any normal, identifying description. However, this difference can be accounted for alternatively by appeal to the semantics of the modal expressions. On the account we suggest, dubbed 'relational modality', simple singular terms, like proper names, contribute to modal contexts simply by their actual world reference, not by their descriptive content. That account turns out to be fully equivalent with the rigidity account when it comes to truth of modal and non-modal sentence (with respect to the actual world), and hence supports the same basic intuitions. Here we present the relational modality account and compare it with others, in particular Kripke's own. (shrink)

In 1942, before his duties began in the USA Navy, W.V. Quine lectured at the Free School of Sociology and Politics of São Paulo. He wrote up the lectures in Por.

In 1942, before his duties began in the USA Navy, W.V. Quine lectured at the Free School of Sociology and Politics of São Paulo. He wrote up the lectures in Por.

By a logical theory I mean a formal system together with its semantics, meta-theory, and rules for translating ordinary language into its notation. Logical theories can be used descriptively (for example, to represent particular arguments or to depict the logical form of certain sentences). Here the logician uses the usual methods of empirical science to assess the correctness of his descriptions. However, the most important applications of logical theories are normative, and here, I argue, the epistemology is that of wide (...) reflective equilibrium. The result is that logic not only assesses our inferential practice but also changes it. I tie my discussion to Thagard's views concerning the relationship between psychology and logic, arguing against him that psychology has and should have only a peripheral role in normative (and most descriptive) applications of logic. (shrink)

Riggs v. Palmerhas become famous since Dworkin used it to show that legal positivism is defective. The debate over the merits of Dworkin's claims is still very lively. Yet not enough attention has been paid to the fact that the content of the statute at issue inRiggswas given by thecounterfactual intentionof the legislature. According to arguments from legislative intent, a judicial decision is justified if it is based on the lawmaker's intention. But can legislative intentions be determined counterfactually? More generally, (...) what are the discursive commitments undertaken by a lawyer or a judge, in an exchange of legal reasons, when using this interpretive methodology? This paper addresses these issues considering, in particular, David Lewis's “resemblance” condition and “relevant similarity” between possible worlds in the evaluation of counterfactual statements. The analysis sheds some new light on the debate on theoretical disagreements and shows that Dworkin's conception of law as an argumentative practice is not necessarily at odds with legal positivism. It rather allows us to look at it under a better light. (shrink)

Plural Logic is an extension of First-Order Logic which has, as well as singular terms and quantifiers, their plural counterparts. Analogously, Higher-Level Plural Logic is an extension of Plural Logic which has, as well as plural terms and quantifiers, higher-level plural ones. Roughly speaking, higher-level plurals stand to plurals like plurals stand to singulars; they are pluralised plurals. Allegedly, Higher-Level Plural Logic enjoys the expressive power of a simple type theory while committing us to nothing more than the austere ontology (...) of First-Order Logic. Were this true, Higher-Level Plural Logic would be a useful tool, with various applications in philosophy and linguistics. However, while the notions of plural reference and quantification enjoy widespread acceptance today, their higher-level counterparts have been received with a lot of scepticism. In this paper, I argue for the legitimacy of Higher-Level Plural Logic by providing evidence to the effect that natural languages contain higher-level plural expressions and showing that it is likely that they do so in an indispensable manner. Since the arguments I put forward are of the same sort advocates of Plural Logic have employed to defend their position, I conclude that the commonly held view that Plural Logic is legitimate, but not so its higher-level plural extensions is untenable. (shrink)

Plural identity—the relation of identity between some things xx and some things yy—has been standardly defined in terms of the plural relation one of (or among). This paper challenges that standard view. To that end, it will be argued, first, that the identity relation, singular or plural, can only be defined in a higher-order language, second, that the standard definition of plural identity in terms of the one of (or among) relation should be regarded instead as providing a criterion of (...) identity for pluralities of some particular kind, and third, that there are pluralities of another kind with which a different criterion of identity is associated. The upshot will be that plural identity as standardly defined cannot be the plural counterpart of singular identity. (shrink)

The notion of similarity plays a central role in Quine's theory of Universals and it is with the help of this notion that Quine intends to define the concept of kind which also plays a central role in the theory. But as Quine has admitted, his attempts to define kinds in terms of similarities were unsuccessful and it is mainly because of this shortcoming that Quine's theory has been ignored by several philosophers. Nominalism and realism: Universals and Scientific realism. Cambridge: (...) Cambridge University Press). In the present paper, I propose an alternative framework that accounts for the phenomena that Quine intends to explain with his resemblance theory. The framework agrees with Quine's austere ontology; in particular, it does not assume the existence of properties and of possible worlds.. Resemblance nominalism: A solution to the problem of Universals. Oxford: Clarendon Press.) Moreover, the framework is extensionalist since the abstract entities it assumes are classes and these can be individuated extensionally, for classes are identical if their members are identical. Finally, I will refute some of the objections to Quine's approach that have been raised by Armstrong and Oliver [. The metaphysics of properties. Mind, 105, 1-80.] and I will argue that, contrary to what has been claimed by Oliver in a comment on Lewis [. On the plurality of worlds. Oxford: Blackwell.], Quine is able to specify an important set of sparse properties. (shrink)

The text consists of two parts. Part one puts the works of Hans Blumenberg, as far as they tackle the problem of rhetoric, into their historical context. Relevant here in particular is the tradition of topological philosophies of the Renaissance and their different types of revival in the 20th century. Part two analyses three main ‘absolute metaphors’ or ‘topoi’ Hans Blumenberg has investigated, the metaphors of ‘light’, ‘shipwreck’, and ‘book of nature’, in order to add to the philosophical perspective taken (...) by Blumenberg a hidden philological perspective, which shows the shortcomings of conceptualizing rhetorical techne (how does a metaphor work), which does not always account for philological techne (how do we write texts). (shrink)

§13 of Principia Ethica contains G. E. Moore’s most famous open question arguments. Several of Moore’s contemporaries defended various forms of metaethical nonnaturalism—a doctrine Moore himself endorsed—by appeal to OQAs. Some contemporary cognitivists embrace the force of Moore’s OQAs against metaethical naturalism. And those who posit noncognitivist meaning components of ethical terms have traditionally used OQAs to fuel their own emotivist, prescriptivist, and expressivist metaethical programs. Despite this influence, Moore’s OQAs have been ridiculed in recent decades. Their deployment has been (...) labeled “accident prone,” “simple to dismiss,” and just plain invalid. Critics accuse Moore of begging the question. Others argue that his OQAs founder upon the paradox of analysis. And still others argue that Moore’s open question argumentation is incompatible with the Kripke–Putnam causal theory of reference and thus it “simply fails; it is bankrupt”. I aim to show that there is something of continuing value in Moore’s open question efforts. I present and criticize Nicholas Sturgeon’s influential interpretation of Moore’s OQAs as a means to motivate and explicate my own interpretation of Moore’s thoughts in §13 of Principia Ethica. I then articulate the role that OQAs are intended to play in Moore’s overall argumentative strategies to undermine metaethical naturalism and thereby provide some theoretical support for metaethical nonnaturalism. Finally, I attend to the most prominent objections to Moore’s theorizing and attempt to evaluate the extent to which Moore’s efforts are successful. My hope is to display both the promising portions of Moore’s metaethical argumentation in Principia Ethica as well as its limitations. (shrink)

This article focuses on defective conditionals ? namely indicative conditionals whose antecedents are false and whose truth-values therefore cannot be determined. The problem is to decide which formal connective can adequately represent this usage. Classical logic renders defective conditionals true whereas traditional mathematics dismisses them as irrelevant. This difference in treatment entails that, at the propositional level, classical logic validates some sentences that are intuitively false in plane geometry. With two proofs, I show that the same flaw is shared by (...) a family of trivalent logics. I go on to examine the strict conditional and its derivatives. This family is the only one to avoid the faulty inference but it does so without addressing the status of the truth-value assigned to defective conditionals. (shrink)

Since Kaplan : 81–98, 1979) first provided a logic for context-sensitive expressions, it has been thought that the only way to construct a logic for indexicals is to restrict it to arguments which take place in a single context— that is, instantaneous arguments, uttered by a single speaker, in a single place, etc. In this paper, I propose a logic which does away with these restrictions, and thus places arguments where they belong, in real world conversations. The central innovation is (...) that validity depends not just on the sentences in the argument, but also on certain abstract relations between contexts. This enrichment of the notion of logical form leads to some seemingly counter-intuitive results: a sequence of sentences may make up a valid argument in one sequence of contexts, and an invalid one in another such sequence. I argue that this is an unavoidable result of context sensitivity in general, and of the nature of indexicals in particular, and that reflection on such examples will lead us to a better understanding of the idea of applying logic to context sensitive expressions, and thus to natural language in general. (shrink)

Epistemic rationality seems to permit a more steadfast response to disagreements over our fundamental convictions than it does for our ordinary beliefs. Why is this? This essay explores three answers to this question: web-of-belief conservatism, moral encroachment, and hinge theories, and argues that hinge theories do a better job than the alternatives at vindicating the intuition that there is a rationally permissible asymmetry in our responses to disagreements over ordinary beliefs and fundamental convictions. The essay also shows how hinge theorists (...) can explain the existence of moral hinge propositions, which enables them to account for the rational permissibility of being steadfast in response to disagreements over fundamental moral convictions. (shrink)