Truth, Sense and Reference

Books reviewed in this essay:
Wolfgang Carl, Frege's Theory of Sense and Reference: Its Scope and its Origins
William P. Alston, A Realist Conception of Truth     

Tarski On Logical Notions

We try to explain Tarski's conception of logical notions, as it emerges from alecture of his, delivered in 1966 and published posthumously in 1986 (Historyand Philosophy of Logic 7, 143–154), a conception based on the idea ofinvariance. The evaluation of Tarski's proposal leads us to consider an interesting(and neglected) reply to Skolem in which Tarski hints at his own point of view onthe foundations of set theory. Then, comparing the lecture of 1966 with Tarski'slast work and with an earlier paper written with Lindenbaum, it is shown thatTarski's conception of logical notions, with its essentially type-theoretic character,did not undergo any significant modifications throughout his life. A remark onTarski's prudential attitude on the topic in the famous paper on the concept oflogical consequence (and elsewhere) concludes our paper.     

论逻辑常项的归约

逻辑联结词和量词都是逻辑的核心概念之一。2004年以来陆续出版的多卷本《逻辑史手册》,计划在第11卷专门以一卷的篇幅来研究后承关系、量词、否定、联结词、模态、自然推演、逻辑图等     

The Basic Constructive Logic for a Weak Sense of Consistency defined with a Propositional Falsity Constant

The logic B_Kc1 is the basic constructive logic in the ternaryrelational semantics (without a set of designated points) adequateto consistency understood as the absence of the negation ofany theorem. Negation is introduced in B_Kc1 with a negationconnective. The aim of this paper is to define the logic B_Kc1F.In this logic negation is introduced via a propositional falsityconstant. We prove that B_Kc1 and B_Kc1F are definitionally equivalent.     

论逻辑后承概念

塔尔斯基在其1933年的论文中基于自己开创的语义学定义了形式化语言中真这个概念。然后,他在发表于1936年的本文中,在真这个概念的定义的基础上,第一次为后承概念提出了一个实质恰当的定义,即“句子X从类K的句子逻辑地得出当且仅当K这个类的每个模型也是句子X的模型”,使得逻辑后承这个现代逻辑核心概念的定义成为标准定义。但是,这个定义也遗留了一个更为根本的问题,即逻辑词项和非逻辑词项的划分标准问题,后者将由塔尔斯基本人在1966年给出了一个划分标准,从而开辟了一个方兴未衰的逻辑哲学研究方向。     

逻辑图表的发展

长期以来,逻辑图表被逻辑学家们仅仅视为教学辅助工具;但逻辑图表从Euler图到Venn图再到存在图表和概念图表的发展表明,它已经超越出教学工具这一狭隘界限,从而获得了更为深刻,广泛的意义,实际上逻辑图表是与我们标准数理逻辑记法相区别的另一种有效的逻辑记法,而且有着更强的直观性和可应用性。     

The Definition of Moral Dilemmas: A Logical Problem

This paper concerns one of the undecided disputes of modern moral philosophy: the possibility of moral dilemmas. Whereas proponents of the possibility of moral dilemmas often appeal to moral experience, many opponents refer to ethical theory and deontic logic. My aim in this paper is to clarify some of the tension between moral experience and ethical theory with respect to moral dilemmas. In Part One I try to show that a number of logical arguments against the possibility of moral dilemmas, though apparently very different, turn out to be basically the same, as they are all based on the following concept of ought: if A ought to be done, doing B is impermissible and doing A itself is permissible. In Part Two I present an overview of several definitions of moral dilemmas that have been given by proponents of moral dilemmas: definitions that define moral dilemmas in terms of oughts and definitions that define them in terms of reasons. I conclude that, while reason is to weak, ought is too strong a concept to define moral dilemmas with. In this way, the arguments from Part One create a logical problem for proponents of the possibility of moral dilemmas to define moral dilemmas.     

论“逻辑在先”的哲学意义

黑格尔曾经指出要进入并研究哲学"需要一种特殊的能力和技巧"[1];柏格森更为明确地讲"研究哲学,就在于扭转思想活动的习惯方向."[2]进而言之,这一扭转乃是进人哲学研究的"门槛",只有跨越了这一门槛,才有可能登堂入室.这一门槛就是:从时间在先转向逻辑在先.     

On the Logical Form of Concessive Conditionals

This paper outlines an account of concessive conditionals that rests on two main ideas. One is that the logical form of a sentence as used in a given context is determined by the content expressed by the sentence in that context. The other is that a coherent distinction can be drawn between a reading of ‘if’ according to which a conditional is true when its consequent holds on the supposition that its antecedent holds, and a stronger reading according to which a conditional is true when its antecedent supports its consequent. As we will suggest, the logical form of concessive conditionals can be elucidated by relying on this distinction.

     

On the Referential Indeterminacy of Logical and Mathematical Concepts

Hartry Field has recently examined the question whether our logical and mathematical concepts are referentially indeterminate. In his view, (1) certain logical notions, such as second-order quantification, are indeterminate, but (2) important mathematical notions, such as the notion of finiteness, are not (they are determinate). In this paper, I assess Fields analysis, and argue that claims (1) and (2) turn out to be inconsistent. After all, given that the notion of finiteness can only be adequately characterized in pure second-order logic, if Field is right in claiming that second-order quantification is indeterminate (see (1)), it follows that finiteness is also indeterminate (contrary to (2)). After arguing that Field is committed to these claims, I provide a diagnosis of why this inconsistency emerged, and I suggest an alternative, consistent picture of the relationship between logical and mathematical indeterminacy.     

On the Concept of a Sense

Keeley has recently argued that the philosophical issue of how to analyse the concept of a sense can usefully be addressed by considering how scientists, and more specifically neuroethologists, classify the senses. After briefly outlining his proposal, which is based on the application of an ordered set of individually necessary and jointly sufficient conditions for modality differentiation, I argue, by way of two complementary counterexamples, that it fails to account fully for the way the senses are in fact individuated in neuroethology and other relevant sciences. I suggest substantial modifications to Keeley’s account which would both solve the problem cases and make better sense of the actual classifications made by scientists. I conclude by noting some limits to the way of classifying the senses that I suggest. I conclude by suggesting that the problem I identify in Keeley’s account has arisen from a confusion that sometimes arises in the philosophical literature between how we individuate the senses and what constitutes a sense.     

A Logical Theory of Localization

A central problem in applying logical knowledge representation formalisms to traditional robotics is that the treatment of belief change is categorical in the former, while probabilistic in the latter. A typical example is the fundamental capability of localization where a robot uses its noisy sensors to situate itself in a dynamic world. Domain designers are then left with the rather unfortunate task of abstracting probabilistic sensors in terms of categorical ones, or more drastically, completely abandoning the inner workings of sensors to black-box probabilistic tools and then interpreting their outputs in an abstract way. Building on a first-principles approach by Bacchus, Halpern and Levesque, and a recent continuous extension to it by Belle and Levesque, we provide an axiomatization that shows how localization can be realized wrt a basic action theory, thereby demonstrating how such capabilities can be enabled in a single logical framework. We then show how the framework can also enable localization for multiple agents, where an agent can appeal to the sensing already performed by another agent and the knowledge of their relative positions to localize itself.