非形式论证的评价方法

一非形式论证 (informalargument)是与形式论证相区别的逻辑论证。形式论证是形式逻辑研究的内容 ,非形式论证是非形式逻辑 (informallogic)的研究内容。非形式逻辑于 2 0世纪70年代在美国兴起 ,用“非形式”命名这种逻辑 ,意指这是一种不严格的逻辑。形式论证具有固定的结构 ,要求结论从前提演绎得出 ,否则论证无效。非形式论证的结构常常不明显 ,它不单纯要求结论从前提必然得出 ,也允许结论得到前提足够的支持 ,仅当前提对结论的支持不足够时 ,才认为论证是谬误。对于论证 ,形式逻辑关注它的演绎有效性问题 ,非形式逻辑关注它的有效性程…     

非形式逻辑及其早期历史发展

“非形式逻辑”作为逻辑的子领域,最初出现于1970至1980年代的美国和加拿大,本文意在回顾非形式逻辑发展的早期历史进程。本文假定,当我们从历史的角度来考察时,非形式逻辑的本质能够得以阐明。因此,我将以观念史领域的评论作为出发点。之所以不从理论的要素谈起并把历史留给历史学家,其中一个理由在于“非形式逻辑”这个词并不指示一个理论。非形式逻辑部分地可看作是某个思潮,部分地可当作一种论证研究进路,部分地涉及到对逻辑之本质的看法,这些都可以通过考察非形式逻辑的发展史来加以理解。本文的第一部分追溯了非形式逻辑的兴起,概括了其思想史和社会史,并评述了其早期发展中的主要人物、教科书,以及主要的论旨及其社会化。第二部分简要描述了《逻辑的自我辩护》这本教科书中的一些革新。第三部分简要涉及非形式逻辑与其它领域的早期互动。     

论证的形式模型概述及其在哲学上的应用

论证是一个用理由支持观点以及回应其所受攻击的过程。在过去的几十年里,论证已经成为哲学和人工智能研究领域中的一个重要主题。在哲学方面,十九世纪50年代和60年代图尔敏和佩雷尔曼对形式逻辑的批判,促进了非形式逻辑这一学科的产生,它研究推理和论证的非形式模型。在人工智能方面,论证的形式模型也发展成为常识推理和多主体冲突解决的基本模型。本文将讨论后一领域中所研究发展的形式模型如何能够用以澄清一些哲学领域、以及非形式逻辑领域中的理论问题和争议。本文的一个重要观点是,图尔敏和佩雷尔曼时代的形式逻辑只关注数学化的推理,但那些非数学化的推理形式其实同样也能够被形式化。     

家的哲学：解释还是辩护

在过去十几年中,作为中国传统哲学现代性转化的一种努力,笑思、张祥龙和孙向晨等学者在汉语哲学的语境中,解释和辩护传统儒家思想中家的哲学,回应现代化的冲击。但是,这种努力面临着外部挑战和内部挑战。当代哲学中方法论上的自然主义、认识论上的多元主义和实践哲学中的个人主义,构成了家的哲学的外部挑战。而家的哲学存在的三种不同解读之间的张力则构成了内部挑战。家的哲学到底是作为一项解释的工作,用来阐释家在儒家思想中的核心地位,还是作为一项辩护的工作,用来辩护家的客观性、必然性和普遍性价值,这构成了家的哲学最大的挑战。家的哲学需要回应这些挑战。     

非形式逻辑——一个新的逻辑学分支

非形式逻辑是六十年代末至七十年代初产生于欧美的一个新的逻辑学分支。它的历史虽然十分短暂,但很受人们关注,发展十分迅速。目前涉足这一领域的学者较一致的看法是,非形式逻辑的研究对象是论证。这一看法也开始得到社会的公认。自然,对非形式逻辑研究对象所作探索的角度和方法是不尽相同的。本文拟就非形式逻辑的产生及主要理论作一简要介绍。非形式逻辑的萌发,与逻辑课堂教学中遇到的困难相关。最初,逻辑教师在教学中     

从“思辨哲学”到“文化哲学”的转向

20世纪以来,思辨哲学向文化哲学的转向昭示了时代对哲学的呼唤.思辨哲学将世界二重化,这既是它的理论前提也是其思想结果;以逻辑方法的科学性为开端,以信念方法的非科学性而终结;以宇宙本体为开端以理性概念认识为终结.     

达米特的辩护主义真理观

达米特从反实在论出发,通过探讨真概念与语义理论的关系、真与意义的关系,提出了一种弱化的真概念。通过将真理理解为人们对于陈述句的一种辩护的能力,提出了一种辩护主义的真理观。主张把“语力”因素作为语义理论的支柱,把语句的真值条件与这种语言的使用实践紧密联系起来,体现了语言哲学中的语用学转向,也体现出解释学对分析哲学的影响和渗透。达米特的辩护主义真理观尽管存在理论上的缺陷并引起较大争论,但它以一种全新的视角来理解真理,在学术界产生了重要的影响。     

早期逻辑经验主义中的社会科学哲学——激进物理主义的情况

逻辑经验主义的社会科学哲学常常受到忽略,但事实上,第二次世界大战之前的早期逻辑经验主义者中,其核心成员纽拉特致力于社会科学元理论研究,并提出了物理主义的社会科学思想。像逻辑经验主义一样,纽拉特也主张科学统一,但他提出的百科全书式的统一思想,其目的就是为了克服一元论框架的统一科学观,反对把社会科学规律还原为物理学规律,也反对方法论个人主义,并从说明原则的类型上论证了社会科学律则的不可还原性。纽拉特的非还原物理主义思想并不要求社会科学能像自然科学那样来运作,社会科学实践中存有大量不可预见的现象。当然这既没有导致经验社会科学终结,也没有导致科学统一理想终结,而是表明正统逻辑经验主义的形式主义科学说明以及科学统一的复杂等级观念并无多大意义。门格尔、考夫曼和齐塞尔这些逻辑经验主义的边缘成员,与纽拉特既有共同之处又有深刻分歧,他们之间在对社会科学本质理解上存在的争议推动了社会科学哲学的发展。     

编者导语

逻辑与哲学的关系不仅是方法论层面的问题,也是思想本身的问题。在西方哲学史上,逻辑与形而上学和认识论的关系极其密切,达米特曾言道：逻辑一直正确地被看做哲学的一部分。这种看法是正确的,不仅因为逻辑后承（logical consequence）这个概念是一种成功的哲学必定要加以分析的概念,而且因为对许多其它概念的分析,对语言的基本结构因而对思想的基本结构的理解,都依赖于以一种正确的形式拥有对句子的构造和句子之间的相互关系的解释,而这种解释正是逻辑要做的事情。1逻辑在19世纪后半叶转向现代发展阶段,同时哲学内部也发生了革命。如今的逻辑理论、技术和方法已经发展十分成熟,运用数学工具对逻辑理论的研究取得了相当丰富的成果。如何运用逻辑理论发展的成果,不被眼花缭乱的逻辑理论所迷惑,努力推进哲学问题的讨论,这是值得认真思考的问题。要运用逻辑理论,首先要掌握逻辑理论（不仅要学会逻辑的技术和方法,而且要理解逻辑理论的实质）,否则应用就是空谈。这里我们组织“逻辑与哲学”专栏,希望通过它向我国逻辑界展示逻辑与哲学研究的成果,逐渐推动我国学者在运用逻辑理论研究哲学问题方面不断取得进步。     

心理因果性、排他性论证与非还原物理主义

在有关心理因果性的当代争论中,非还原物理主义无疑是个备受青睐或关注的哲学立场。而金在权的排他性论证则是一个被广泛用来质疑非还原物理主义的著名论证。本文首先考察排他性论证的两个版本(简化版和复杂版)。然后,为由戴维森首创的非还原物理主义的一支——殊型同一论进行辩护。与当前大多数辩护方案有所不同的是,本文采取了一个保守辩护策略来回应排他性论证:具体指出,金在权究竟在什么地方未能恰当地理解戴维森的工作;并且表明,经过澄清之后的殊型同一论完全可以免受排他性论证的困扰(无论是简化版还是复杂版)。最后,本文还揭示了金在权对戴维森相关工作的不恰当理解,乃源于更深层的形而上学分歧。因此有理由认为,只有在一个合适的形而上学框架中,我们才能够恰当地理解和评估有关心理因果性、非还原物理主义及其相关问题的思考。     

Logical Constraints on Judgement Aggregation

Logical puzzles like the doctrinal paradox raise the problem of how to aggregate individual judgements into a collective judgement, or alternatively, how to merge collectively inconsistent knowledge bases. In this paper, we view judgement aggregation as a function on propositional logic valuations, and we investigate how logic constrains judgement aggregation. In particular, we show that there is no non-dictatorial decision method for aggregating sets of judgements in a logically consistent way if the decision method is local, i.e., only depends on the individual judgements on the proposition under consideration.     

A Logical Account of Formal Argumentation

In the current paper, we re-examine how abstract argumentation can be formulated in terms of labellings, and how the resulting theory can be applied in the field of modal logic. In particular, we are able to express the (complete) extensions of an argumentation framework as models of a set of modal logic formulas that represents the argumentation framework. Using this approach, it becomes possible to define the grounded extension in terms of modal logic entailment.     

Leibniz and the Square: A Deontic Logic for the Vir Bonus

Seventeenth century philosopher Gottfried Leibniz's contributions to metaphysics, mathematics, and logic are well known. Lesser known is his ‘invention’ of deontic logic, and that his invention derives from the alethic logic of the Aristotelian square of opposition. In this paper, I show how Leibniz developed this ‘logic of duties’, which designates actions as ‘possible, necessary, impossible, and omissible’ for a ‘vir bonus’ (good person). I show that for Leibniz, deontic logic can determine whether a given action, e.g. as permitted, is therefore obligatory or prohibited (impossible). Secondly, since the deontic modes are derived from what is possible, necessary, etc., for a good person to do, and that ‘right and obligation’ are the ‘moral qualities’ of a good person, we can see how Leibniz derives deontic logic from these moral qualities. Finally, I show how Leibniz grounds a central deontic concept, namely obligation, in the human capacity for freedom.     

Speakable in quantum mechanics

At the 1927 Como conference Bohr spoke the famous words “It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature.” However, if the Copenhagen interpretation really adheres to this motto, why then is there this nagging feeling of conflict when comparing it with realist interpretations? Surely what one can say about nature should in a certain sense be interpretation independent. In this paper I take Bohr’s motto seriously and develop a quantum logic that avoids assuming any form of realism as much as possible. To illustrate the non-triviality of this motto, a similar result is first derived for classical mechanics. It turns out that the logic for classical mechanics is a special case of the quantum logic thus derived. Some hints are provided as to how these logics are to be used in practical situations and finally, I discuss how some realist interpretations relate to these logics.     

A Logical Analysis of Monty Hall and Sleeping Beauty

Hintikka and Sandu’s independence-friendly (IF) logic is a conservative extension of first-order logic that allows one to consider semantic games with imperfect information. In the present article, we first show how several variants of the Monty Hall problem can be modeled as semantic games for IF sentences. In the process, we extend IF logic to include semantic games with chance moves and dub this extension stochastic IF logic. Finally, we use stochastic IF logic to analyze the Sleeping Beauty problem, leading to the conclusion that the thirders are correct while identifying the main error in the halfers’ argument.     

Frege on the generality of logical laws

Frege claims that the laws of logic are characterized by their “generality,” but it is hard to see how this could identify a special feature of those laws. I argue that we must understand this talk of generality in normative terms, but that what Frege says provides a normative demarcation of the logical laws only once we connect it with his thinking about truth and science. He means to be identifying the laws of logic as those that appear in every one of the scientific systems whose construction is the ultimate aim of science, and in which all truths have a place. Though an account of logic in terms of scientific systems might seem hopelessly antiquated, I argue that it is not: A basically Fregean account of the nature of logic still looks quite promising.     

Some unifying fixed point principles

This article is written for both the general mathematican and the specialist in mathematical logic. No prior knowledge of metamathematics, recursion theory or combinatory logic is presupposed, although this paper deals with quite general abstractions of standard results in those three areas. Our purpose is to show how some apparently diverse results in these areas can be derived from a common construction. In Section 1 we consider five classical fixed point arguments (or rather, generalizations of them) which we present as problems that the reader might enjoy trying to solve. Solutions are given at the end of the section. In Section 2 we show how all these solutions can be obtained as special cases of a single fixed point theorem. In Section 3 we consider another generalization of the five fixed point results of Section 1 and show that this is of the same strength as that of Section 2. In Section 4 we show some curious strengthenings of results of Section 3 which we believe to be of some interest on their own accounts.     

Reasoning About Social Choice Functions

We introduce a logic specifically designed to support reasoning about social choice functions. The logic includes operators to capture strategic ability, and operators to capture agent preferences. We establish a correspondence between formulae in the logic and properties of social choice functions, and show that the logic is expressively complete with respect to social choice functions, i.e., that every social choice function can be characterised as a formula of the logic. We prove that the logic is decidable, and give a complete axiomatization. To demonstrate the value of the logic, we show in particular how it can be applied to the problem of determining whether a social choice function is strategy-proof.     

Entailment and Bivalence

My purpose in this paper is to argue that the classical notion of entailment is not suitable for non-bivalent logics, to propose an appropriate alternative and to suggest a generalized entailment notion suitable to bivalent and non-bivalent logics alike. In classical two valued logic, one can not infer a false statement from one that is not false, any more than one can infer from a true statement a statement that is not true. In classical logic in fact preserving truth and preserving non-falsity are one and the same thing. They are not the same in non-bivalent logics however and I will argue that the classical notion of entailment that preserves only truth is not strong enough for such a logic. I will show that if we retain the classical notion of entailment in a logic that has three values, true, false and a third value in between, an inconsistency can be derived that can be resolved only by measures that seriously disable the logic. I will show this for a logic designed to allow for semantic presuppositions, then I will show that we get the same result in any three valued logic with the same value ordering. I will finally suggest how the notion of entailment should be generalized so that this problem may be avoided. The strengthened notion of entailment I am proposing is a conservative extension of the classical notion that preserves not only truth but the order of all values in a logic, so that the value of an entailed statement must alway be at least as great as the value of the sequence of statements entailing it. A notion of entailment this strong or stronger will, I believe, be found to be applicable to non-classical logics generally. In the opinion of Dana Scott, no really workable three valued logic has yet been developed. It is hard to disagree with this. A workable three valued logic however could perhaps be developed however, if we had a notion of entailment suitable to non-bivalent logics.     

‘In the Beginning is Relation’: Martin Buber’s Alternative to Binary Oppositions

In this article we develop a relational understanding of sociality, that is, an account of social life that takes relation as primary. This stands in contrast to the common assumption that relations arise when subjects interact, an account that gives logical priority to separation. We will develop this relational understanding through a reading of the work of Martin Buber, a social philosopher primarily interested in dialogue, meeting, relationship, and the irreducibility and incomparability of reality. In particular, the article contrasts Buber??s work with that of poststructuralist theorists who take as their starting point the deconstruction of the Hegelian logic of binary oppositions. Deconstruction understands difference as the excess that undoes the binary, but Buber, we argue, shows how difference derives from the primacy and ontological undefinability of relation. Relational logic does not exclude the logic of separations and oppositions: relation is the primal ground that makes separations possible.