Dynamics we can believe in: a view from the Amsterdam School on the centenary of Evert Willem Beth

Logic is breaking out of the confines of the single-agent static paradigm that has been implicit in all formal systems until recent times. We sketch some recent developments that take logic as an account of information-driven interaction. These two features, the dynamic and the social, throw fresh light on many issues within logic and its connections with other areas, such as epistemology and game theory.     

The information in intuitionistic logic

Issues about information spring up wherever one scratches the surface of logic. Here is a case that raises delicate issues of ‘factual’ versus ‘procedural’ information, or ‘statics’ versus ‘dynamics’. What does intuitionistic logic, perhaps the earliest source of informational and procedural thinking in contemporary logic, really tell us about information? How does its view relate to its ‘cousin’ epistemic logic? We discuss connections between intuitionistic models and recent protocol models for dynamic-epistemic logic, as well as more general issues that emerge.     

An analytic tableau calculus for a temporalised belief logic

A tableau is a refutation-based decision procedure for a related logic, and is among the most popular proof procedures for modal logics. In this paper, we present a labelled tableau calculus for a temporalised belief logic called TML⁺, which is obtained by adding a linear-time temporal logic onto a belief logic by the temporalisation method of Finger and Gabbay. We first establish the soundness and the completeness of the labelled tableau calculus based on the soundness and completeness results of its constituent logics. We then sketch a resolution-type proof procedure that complements the tableau calculus and also propose a model checking algorithm for TML⁺ based on the recent results for model checking procedures for temporalised logics. TML⁺ is suitable for formalising trust and agent beliefs and reasoning about their evolution for agent-based systems. Based on the logic TML⁺, the proposed labelled tableau calculus could be used for analysis, design and verification of agent-based systems operating in dynamic environments.     

中国逻辑元研究

This paper discusses the topics, goals, values and methods of Chinese logic. It holds that the goal of the research in Chinese logic is to reveal its structure, content, rules, and essential character, as well as to reveal both similarities and differences between Chinese and foreign logic. The value of the research is to carry forward and develop the outstanding heritage of Chinese logic. Its method is to annotate original works of Chinese ancient logic with the tools of modern language and logic in order to reveal both the particular nature and the universal qualities of Chinese logic. The method also explores the differences and similarities between Chinese and foreign logic. In recent years, research in Chinese logic has developed considerably; it has also logged many important achievements. But there are many different views about the complexity and long-term goals of the research. Future research will build on the merits of different kinds of logic, promote Chinese logic, and increase communication between Chinese logic and foreign logic. Translated by Song Saihua from Zhongguo Renmin Daxue Xuebao 中国人民大学学报 (Journal of Renmin University of China), 2005, (2): 56–62     

Beyond opposites: Extending the cultural boundaries of CBT methodology

In cognitive behavioural therapy (CBT), a black or white perception of the world is generally considered to be a distortion of reality. This paper addresses the issue of bipolar or categorical thinking and its role in creating disturbance. It introduces a new quantitative methodology known as fuzzy logic (FL) and shows its potential in developing new effective CBT strategies to address bipolar thinking. The paper maintains that the roots of such thinking can be traced back to the Aristotelian logic which posits a 'black or white' view of the world. It is argued that a bipolar perspective is no longer defendable given recent developments in the field of literature, physics and logic. Moreover CBT can derive significant benefits by embracing the fuzzy logic paradigm. In particular it can, first, benefit by improving the degree of precision of its diagnostic tools and, second, by applying the FL principles to derive alternative strategies for inducing healthy changes in clients. Such improvements are believed to enhance CBT profile in terms of the degree of realism, flexibility and efficiency of its methods. The illustrations offered throughout this paper are based on the two main CBT perspectives; rational emotive behaviour therapy (REBT) and cognitive therapy (CT).     

Combinations of <Emphasis Type="Italic">Stit</Emphasis> with <Emphasis Type="Italic">Ought</Emphasis> and <Emphasis Type="Italic">Know</Emphasis>

This paper presents a short survey of recent developments in stit theories, with an emphasis on combinations of stit and deontic logic, and those of stit and epistemic logic.     

广义论证视域下朱熹论辩逻辑体系的考察

近年来,广义论证视域下的中国古代逻辑史研究成为学界关注的热点,在丰硕的研究成果中,仍存在“怎样深化”与“如何拓展”等问题。在广义论证视域下对朱熹论辩逻辑体系进行考察,一方面可以打破以往研究主要集中在先秦时期的囿限,进一步拓展其研究范围;另一方面也可以在逻辑体系的构建中深化中国古代逻辑研究。从广义论证角度看,朱熹的逻辑是“名义界分”“知言穷理”等说理论证规则的集合,基于上述逻辑,朱熹同陆九渊、张栻等人围绕“太极”“仁说”等进行论辩实践,逐步建立起以名、辞理论为基础的“名、辞–辩”的逻辑体系。上述体系对后世影响深远。从广义论证角度考察朱熹论辩逻辑体系,对新时期回应如何做“中国古代逻辑”具有启发意义。     

Modes of Adjointness

The fact that many modal operators are part of an adjunction is probably folklore since the discovery of adjunctions. On the other hand, the natural idea of a minimal propositional calculus extended with a pair of adjoint operators seems to have been formulated only very recently. This recent research, mainly motivated by applications in computer science, concentrates on technical issues related to the calculi and not on the significance of adjunctions in modal logic. It then seems a worthy enterprise (both for these contemporary topical pursuits and also for historical interest) to trace the concept of adjunction back to the origins of the algebraic semantics of modal logic and to make explicit its ubiquity in this branch of mathematics.     

Possibilities,models, and intuitionistic logic: Ian Rumfitt’s The boundary stones of thought

AIan Rumfitt's new book presents a distinctive and intriguing philosophy of logic, one that ultimately settles on classical logic as the uniquely correct one–or at least rebuts some prominent arguments against classical logic. The purpose of this note is to evaluate Rumfitt's perspective by focusing on some themes that have occupied me for some time: (i) the role and importance of model theory and, in particular, the place of counter-arguments in establishing invalidity, (ii) higher-order logic, and (iii) the logical pluralism/relativism articulated in my own recent *Varieties of logic*.     

人类非逻辑思维辨析

按照皮亚杰的观点,成人的思维发展已达到“形式运算”的阶段,能够依据形式逻辑规则进行抽象的合乎逻辑的判断和推理。从此以后,根据逻辑的标准判断人类的推理是否是理性的就自然而然被接受了。然而最近的一些研究发现,人类在现实生活中并不完全遵照形式逻辑的规则来思维,在许多时候都表现出非逻辑的一面,似乎有另一种大家公认的“心理逻辑”。但是,非逻辑并不意味着非理性,从生态学的角度说,很多时候心理逻辑具有理性的一面。     

A Note on Hahn's Philosophy of Logic

Hans Hahn, mathematician, philosopher and co-founder of the Vienna Circle, attempted to reconcile the validity and applicability of both logic and mathematics with a strict empiricism. This article begins with a review of this attempt, focusing on his view of the relation of language to logic and his answer to the question of why we need logic. I then turn to some recent work by Stephen Yablo in an attempt to show that Yablo's fictionalism, and in particular his use of metaphor, can shed light on Hahn's philosophy of logic.     

The demands and capacities model: Response to siegel

Responses to the recent critical comments of Gerald Siegel to the demands and capacities model are given. A brief history of the model's development is followed by direct explanations of its empirical support and logical development. It appears that Dr. Siegel may have referred only to one of our publications on the model. His concern about difficulties in measuring capacities is also addressed. Finally, the logic of the model is explicated and a misunderstanding regarding the use of direct therapy is clarified.     

Framing human inference by coherence based probability logic

We take coherence based probability logic as the basic reference theory to model human deductive reasoning. The conditional and probabilistic argument forms are explored. We give a brief overview of recent developments of combining logic and probability in psychology. A study on conditional inferences illustrates our approach. First steps towards a process model of conditional inferences conclude the paper.     

The Venn-MacColl Dispute in Nature

During 1881, the British logicians John Venn and Hugh MacColl engaged in a brief dispute in Nature about ‘symbolical logic’. The letters to the editor shed interesting light on the early reception of MacColl’s contributions to logic and his position in the logical community of the Victorian era. Drawing on the correspondence between Venn and William Stanley Jevons, this paper analyzes the background and context of these letters, adding to the recent interest in the social dimensions of the development of British algebraic logic in the confusing intermediary period between the 1870s and 1890s.     

Hintikka on the Foundations of Mathematics: IF Logic and Uniformity Concepts

The initial goal of the present paper is to reveal a mistake committed by Hintikka in a recent paper on the foundations of mathematics. His claim that independence-friendly logic (IFL) is the real logic of mathematics is supported in that article by an argument relying on uniformity concepts taken from real analysis. I show that the central point of his argument is a simple logical mistake. Second and more generally, I conclude, based on the previous remarks and on another standard fact of IFL, that first-order logic (FOL) can adequately express uniformity concepts in real analysis, whereas IFL (understood as a non-trivial extension of FOL) cannot. This not only radically contradicts Hintikka’s particular claim in that article, but also undermines his whole enterprise of founding mathematics on his logic system.     

Traditional Logic,Modern Logic and Natural Language

In a recent paper Johan van Benthem reviews earlier work done by himself and colleagues on ‘natural logic’. His paper makes a number of challenging comments on the relationships between traditional logic, modern logic and natural logic. I respond to his challenge, by drawing what I think are the most significant lines dividing traditional logic from modern. The leading difference is in the way logic is expected to be used for checking arguments. For traditionals the checking is local, i.e. separately for each inference step. Between inference steps, several kinds of paraphrasing are allowed. Today we formalise globally: we choose a symbolisation that works for the entire argument, and thus we eliminate intuitive steps and changes of viewpoint during the argument. Frege and Peano recast the logical rules so as to make this possible. I comment also on the traditional assumption that logical processing takes place at the top syntactic level, and I question Johan’s view that natural logic is ‘natural’.     

Action models in inquisitive logic

Synthese - Information exchange can be viewed as a process of asking questions and answering them. While dynamic epistemic logic traditionally focuses on statements, recent developments have been...     

The Logic and Meaning of Plurals. Part I

Contemporary accounts of logic and language cannot give proper treatments of plural constructions of natural languages. They assume that plural constructions are redundant devices used to abbreviate singular constructions. This paper and its sequel, “The logic and meaning of plurals, II”, aim to develop an account of logic and language that acknowledges limitations of singular constructions and recognizes plural constructions as their peers. To do so, the papers present natural accounts of the logic and meaning of plural constructions that result from the view that plural constructions are, by and large, devices for talking about many things (as such). The account of logic presented in the papers surpasses contemporary Fregean accounts in its scope. This extension of the scope of logic results from extending the range of languages that logic can directly relate to. Underlying the view of language that makes room for this is a perspective on reality that locates in the world what plural constructions can relate to. The papers suggest that reflections on plural constructions point to a broader framework for understanding logic, language, and reality that can replace the contemporary Fregean framework as this has replaced its Aristotelian ancestor.     

On Fork Arrow Logic and its Expressive Power

We compare fork arrow logic, an extension of arrow logic, and its natural first-order counterpart (the correspondence language) and show that both have the same expressive power. Arrow logic is a modal logic for reasoning about arrow structures, its expressive power is limited to a bounded fragment of first-order logic. Fork arrow logic is obtained by adding to arrow logic the fork modality (related to parallelism and synchronization). As a result, fork arrow logic attains the expressive power of its first-order correspondence language, so both can express the same input–output behavior of processes.