Carnap: Philosophy of Logic

Carnap’s result about classical proof-theories not ruling out non-normal valuations of propositional logic formulae has seen renewed philosophical interest in recent years. In this note I contribute some considerations which may be helpful in its philosophical assessment. I suggest a vantage point from which to see the way in which classical proof-theories do, at least to a considerable extent, encode the meanings of the connectives (not by determining a range of admissible valuations, but in their own way), and I demonstrate (...) a kind of converse to Carnap’s result. (shrink)

This paper is a conceptual study in the philosophy of logic. The question considered is 'How may formulae of the propositional calculus be brought into a representational relation to the world?'. Four approaches are distinguished: (1) the denotational approach, (2) the abbreviational approach, (3) the truth-conditional approach, and (4) the modelling approach. (2) and (3) are very familiar, so I do not discuss them. (1), which is now largely obsolete, led to some interesting twists and turns in early analytic philosophy (...) which will come as news to many contemporary readers, so I discuss it in some detail. The modelling approach is, to the best of my knowledge, newly introduced here. I am not presenting it as a rival to the other approaches, but as a philosophically interesting possibility. (shrink)

Husserl, in his doctrine of categories, distinguishes what he calls regions from what he calls formal categories. The former are most general domains, while the latter are topic-neutral concepts that apply across all domains. Husserl’s understanding of these notions of category is here discussed in detail. It is, moreover, argued that similar notions of category may be recognized in Carnap’s Der logische Aufbau der Welt.

In an imagined dialogue between two figures called “Carnap*” and “Quine*” that appeared in the Library of Living Philosophers volume in 1986, certain proposals and clarifications of the linguistic doctrine were offered by Carnap* answering Quinean objections, but these were brushed aside rather breezily in a reply to this dialogue in the same volume by Quine himself. After a brief summary of the questions at issue in that earlier dialogue, Carnap* is here allowed a final reply, introducing yet another variant (...) on his series of more precise formulations of the linguistic doctrine of logical truth and touching on other issues raised both by Quine* in the earlier dialogue and by Quine himself in his reply. (shrink)

We characterize those identities and independencies which hold for all probability functions on a unary language satisfying the Principle of Atom Exchangeability. We then show that if this is strengthen to the requirement that Johnson's Sufficientness Principle holds, thus giving Carnap's Continuum of inductive methods for languages with at least two predicates, then new and somewhat inexplicable identities and independencies emerge, the latter even in the case of Carnap's Continuum for the language with just a single predicate.

The paper reconstructs the three main stages in the development of Carnap’s semantics in the years 1935–1947. It starts with Carnap’s approach to metalogic in his Zirkelprotokolle and his Logische Syntax der Sprache from the point of view of one-level approach to the relation between metalanguage and its object-language. It then analyzes Tarski’s turn to semantics in his paper presented at the Paris conference in September 1935, as well as the implications of his view for Carnap’s approach to semantics from (...) 1935 until 1943. Finally, it analyzes Church’s rediscovery of Frege and its impact on Carnap’s shift to the extension/intension distinction in his semantics in the years 1943–1947. (shrink)

Quine’s paper “Two Dogmas of Empiricism” is famous for its attack on analyticity and the analytic/synthetic distinction. But there is an element of Quine’s attack that should strike one as extremely puzzling, namely his objection to Carnap’s account of analyticity. For it appears that, if this objection works, it will not only do away with analyticity, it will also do away with other semantic notions, notions that (or so one would have thought) Quine does not want to do away with, (...) in particular, it will also do away with truth. I shall argue that there is, indeed, no way for Quine to protect truth against the type of argument he himself advanced in “Two Dogmas” against Carnap’s notion of analyticity. If he wants to keep his argument, Quine has to discard truth along with analyticity. At the end of the paper I suggest an interpretation of Quine on which he can be seen as having done just that. (shrink)

The aim of the article is to analyze the situation of contemporary logic with reference to the issue concerning connections between the pluralism of logical systems and relativism in logic. Accordingly, I seek answers to the following questions: Can the plurality of logic, more specifically, a large number and variety of systems constructed by logicians, be justified in a rational way? Does pluralism in logic imply the thesis of relativism? Is logical relativism in the contemporary philosophy of logic just a (...) superstition or is it a duly substantiated view? (shrink)

In this paper I examine the question of logic’s normative status in the light of Carnap’s Principle of Tolerance. I begin by contrasting Carnap’s conception of the normativity of logic with that of his teacher, Frege. I identify two core features of Frege’s position: first, the normative force of the logical laws is grounded in their descriptive adequacy; second, norms implied by logic are constitutive for thinking as such. While Carnap breaks with Frege’s absolutism about logic and hence with the (...) notion that any system of logic should have a privileged claim to correctness, I argue that there is a sense in which Carnap’s framework-relative conception of logical norms has a constitutive role to play: though they are not constitutive for the conceptual activity for thinking, they do nevertheless set the ground rules that make certain forms of scientific inquiry possible in the first place. I conclude that Carnap’s principle of tolerance is tamer than one might have thought and that, despite remaining differences, Frege’s and Carnap’s conceptions of logic have more in common than one might have thought. (shrink)

A brief introduction to the life and key work of Rudolf Carnap with special attention to his work on inductive logic.

Dans les « Deux dogmes», Quine voulait démontrer que le positivisme logique n’était possible qu’en raison d’hypothèses injustifiées. L’intention de Quine était de montrer qu’il n’est possible de sauver l’empirisme que si l’on accepte une autre approche, holistique. Toutefois, l’article de Quine était anachronique dès le moment de sa publication. Le but de cet article est double. Tout d’abord, on esquissera l’argument de Quine et on le confrontera aux positions de Carnap et Dubislav. On montrera que la critique de Quine (...) était en retard d’au moins 15 ans. En deuxième lieu, on examinera le postulat de Quine de l’empirisme sans dogmes et on comparera brièvement à la théorie de Poznański et Wundheiler. On soutiendra que ce postulat avait été réalisé déjà dans les années 1930. (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)