Gödel on Concepts

This article is an attempt to present Gödel's discussion on concepts, from 1944 to the late 1970s, in particular relation to the thought of Frege and Russell. The discussion takes its point of departure from Gödel's claim in notes on Bernay's review of ‘Russell's mathematical logic’. It then retraces the historical background of the notion of intension which both Russell and Gödel use, and offers some grounds for claiming that Gödel consistently considered logic as a free-type theory of concepts, called intensions, considered as the denotations of predicate names.     

Propositions and Reasoning in Russell and Frege

Both Russell and Frege were inclined to think that there is nothing essentially linguistic about thought: any actual reliance of ours upon language is a mere psychological contingency. If so then it should be possible to formulate logic in such a way that logical relationships are not represented or expressed as principles pertaining to linguistic forms. Russell and Frege take pains to achieve this, but fail. I explain this by looking at some features of Grundgesetz and Principia . Their failure, I suggest, is due to the nature of the case.     

Reply to Dr. Lambert

Psychologism in logic holds that logic is a branch of psychology. This view has been vigorously defended by John Stuart Mill and by a number of German philosophers of logic, notably Erdmann. Its chief critics have been Husserl and Frege and, to a lesser extent, Russell. Husserl set forth a profound and detailed critique of psychologism in Logical Investigations. This paper examines this critique. First, I explain why the psychologistic theory is attractive. Then I show that Husserl's critique is not convincing, partly because he does not take the theory in its most plausible form and partly because he ignores certain important distinctions (for example, between what a statement is about and what it is true in virtue of). Then I raise two new objections to the psychologistic theory. The purpose of this paper is to suggest that the psychologistic theory remains an important and serious position from which we can learn much about the status of logic.     

Existential Graphs: What a Diagrammatic Logic of Cognition Might Look Like

This paper examines the contemporary philosophical and cognitive relevance of Charles Peirce's diagrammatic logic of existential graphs (EGs), the ‘moving pictures of thought’. The first part brings to the fore some hitherto unknown details about the reception of EGs in the early 1900s that took place amidst the emergence of modern conceptions of symbolic logic. In the second part, philosophical aspects of EGs and their contributions to contemporary logical theory are pointed out, including the relationship between iconic logic and images, the problem of the meaning of logical constants, the cognitive economy of iconic logic, the failure of the Frege–Russell thesis, and the failure of the Language of Thought hypothesis.     

Beltrami's model and the independence of the parallel postulate

In their correspondence in 1902 and 1903, after discussing the Russell paradox, Russell and Frege discussed the paradox of propositions considered informally in Appendix B of Russell's Principles of Mathematics. It seems that the proposition, p, stating the logical product of the class w, namely, the class of all propositions stating the logical product of a class they are not in, is in w if and only if it is not. Frege believed that this paradox was avoided within his philosophy due to his distinction between sense (Sinn) and reference (Bedeutung). However, I show that while the paradox as Russell formulates it is ill-formed with Frege's extant logical system, if Frege's system is expanded to contain the commitments of his philosophy of language, an analogue of this paradox is formulable. This and other concerns in Fregean intensional logic are discussed, and it is discovered that Frege's logical system, even without its naive class theory embodied in its infamous Basic Law V, leads to inconsistencies when the theory of sense and reference is axiomatized therin. therein.     

The ontological foundation of Russell's theory of modality

Prominent thinkers such as Kripke and Rescher hold that Russell has no modal logic, even that Russell was indisposed toward modal logic. In Part I, I show that Russell had a modal logic which he repeatedly described and that Russell repeatedly endorsed Leibniz's multiplicity of possible worlds. In Part II, I describe Russell's theory as having three ontological levels. In Part III, I describe six Parmenidean theories of being Russell held, including: literal in 1903; universal in 1912; timeless in 1914; transcendental in 1918–1948. The transcendental theory underlies the primary level of Russell's modal logic. In Part IV, I examine Rescher's view that Russell and modal logic did not mix.The United States Naval Academy Research Council kindly provided a summer 1988 research grant for work on this essay. This essay was presented at the Bertrand Russell Society Meeting during the December 1988 Eastern Division Meeting of the American Philosophical Association in Washington, D.C.     

不可超越的无穷：关于直谓性和后继公理的关系

本文首先将新弗雷格主义的发展划分为三个阶段：（1）弗雷格算术（由二阶逻辑和休谟原则构成的理论）的一致性和对于二阶皮亚诺算术公理的可推出性的证明,（2）对休谟原则和二阶逻辑的哲学辩护与反驳,（3）对休谟原则和二阶逻辑进行限制,并证明其一致性和可推出性。然后着重介绍：（1）直谓二阶逻辑和公理V的一致性,（2）直谓二阶逻辑和休谟原则不能推出皮亚诺算术的后继公理。这说明一致性和可推出性在弗雷格系统的直谓片段中不可兼得。最后在直观上做出简单的分析。     

Formality of logic and Frege’s Begriffsschrift

This paper challenges a standard interpretation according to which Frege’s conception of logic (early and late) is at odds with the contemporary one, because on the latter’s view logic is formal, while on Frege’s view it is not, given that logic’s subject matter is reality’s most general features. I argue that Frege – in Begriffsschrift – retained the idea that logic is formal; Frege sees logic as providing the ‘logical cement’ that ties up together the contentful concepts of specific sciences, not the most general truths. Finally, I discuss how Frege conceives of the application of Begriffsschrift, and of its status as a ‘lingua characteristica’.     

概念语义与弗雷格迷题消解

弗雷格因同一替换律讨论而提出了涵义与指称的理论,这个理论后来引出了弗雷格迷题。弗雷格迷题的形成有多方原因,直接指称论对弗雷格理论批评是主要原因之一,以至于可以说,这是产生于直接指称论哲学立场的迷题。尽管如此,弗雷格理论确有不足。最重要的是,弗雷格理论只有关于涵义与指称的理论,即只有语言层面的理论,而缺少认知层面的理论。这个不足使得在弗雷格理论基础上解决同一替换律问题难有令人满意的结果,让"迷题"多添了几分"迷"的色彩。这里将给出一个新的方案:在弗雷格理论的基础上,增加有关概念的理论,以概念和内涵、涵义等这些概念的形式刻画为中心,建立可以消解弗雷格迷题的形式语义学,即概念语义。通过概念语义可以在不同层次上对弗雷格迷题的消解给出统一回答。     

Peter Winch on ‘Aristotelian’ and ‘Socratic’ Reasoning

Peter Winch often returned to questions about the nature of logic. In the context of his work on Wittgenstein and political philosophy in the 1990s, Winch described a contrast between ‘Aristotelian’ and ‘Socratic’ reasoning. Aristotelian conceptions of reasoning, attributed to Frege and Russell, would see logic as a formal science and rationality as consistency with pre‐existent rules of inference. The Socratic conception, attributed to Wittgenstein, understands rational argument as a form of socially embedded dialogue that involves moral relationships and a dimension of depth. Rational persuasion may also involve use of persuasive images and examples.     

语义预设的合理性辩护

弗雷格是第一个注意到命题的预设为假会影响到命题真值判定的哲学家。对这种因预设为假而形成的真值空隙,弗雷格、罗素和斯特劳森提出了不同的处理方式,由此奠定了预设的语义解释的基础。但预设的语义解释一直面临着种种质疑。这些质疑有说服力吗?应该放弃预设的语义解释吗?本文将对此进行分析,揭示这些质疑中所存在的问题,从而对预设的语义解释的合理性进行辩护。一、预设为假与真值空隙第一个把预设作为逻辑概念加以讨论的哲学家是弗雷格,其预设思想可以归纳为四点:第一,预     

The extent of Russell''s modal views

Russell has recently been held to have had a modal logic, a full modal theory and a view of naming that anticipates Kripke's intuitions on rigid designation. It is argued here that no such claims are warranted. While Russell was not altogether silent on matters modal, he did not advance an identifiable modal logic or anything more than a modest modal theory. His view of naming involves a notion of guaranteed reference. But what Kripke's intuitions about rigidity primarily pertain to is fixed reference, something demonstrably different.     

Frege on Truth,Assertoric Force and the Essence of Logic

In a posthumous text written in 1915, Frege makes some puzzling remarks about the essence of logic, arguing that the essence of logic is indicated, properly speaking, not by the word ‘true’, but by the assertoric force. William Taschek has recently shown that these remarks, which have received only little attention, are very important for understanding Frege's conception of logic. On Taschek's reconstruction, Frege characterizes logic in terms of assertoric force in order to stress the normative role that the logical laws play vis-à-vis judgement, assertion and inference. My aim in this paper is to develop and defend an alternative reconstruction according to which Frege stresses that logic is not only concerned with ‘how thoughts follow from other thoughts’, but also with the ‘step from thought to truth-value’. Frege considers logic as a branch of the theory of justification. To justify a conclusion by means of a logical inference, the ‘step from thought to truth-value’ must be taken, that is, the premises must be asserted as true. It is for this reason that, in the final analysis, the assertoric force indicates the essence of logic, for Frege.     

Louis Couturat,modern logic,and the international auxiliary language

ABSTRACT

To some extent, the early twentieth century revival of universal languages was the work of logicians and mathematicians. Pioneers of modern logic such as Frege, Russell and Peano wanted to overcome the diversity and deficiencies of natural languages. Through the rigour of formal logic, they aimed at providing scientific thinking with a reliable medium free from the ambiguity and inconsistencies of ordinary language. This article shows some interconnections between modern logic and the search for a common tongue that would unite scientists and people of all nations. The French mathematician and philosopher Louis Couturat is a key figure in understanding the interplay between these two movements. Through his work in composing the Ido language as an alternative to Esperanto, Couturat gave a new life to the Leibnizian idea of a universal characteristics. In addition, his multifaceted work provides a valuable insight into some political implications of early analytic philosophy.     

Kant,wittgenstein and the limits of logic

This paper has two purposes. (1) To justify the claim that there is an important distinction underlying the saying/showing distinction of the Tractatus; the distinction which Kant characterises as that between historical and rational knowledge. (2) To argue that it is because the Tractatus accepts Frege/Russell logic as a complete representation of all thought according to laws, that what is shown cannot be recognised as knowledge. This is done by interpolating Frege's logical innovations between the views of Kant and Wittgenstein on logic and mathematics.     

Analysis and Decomposition in Frege and Russell

Michael Dummett has long argued that Frege is committed to recognizing a distinction between two sorts of analysis of propositional contents: 'analysis', which reveals the entities that one must grasp in order to apprehend a given propositional content; and 'decomposition', which is used in recognizing the validity of certain inferences. Whereas any propositional content admits of a unique ultimate 'analysis' into simple constituents, it also admits of distinct 'decompositions', no one of which is ultimately privileged over the others. I argue that although Russell accepts this distinction between analysis and decomposition, Frege does not. In particular, I consider claims which Dummett makes regarding how 'analysis' and 'decomposition' are related to two different models Frege at least suggests in discussing the composition of thoughts, the part/whole model and the function/argument model; and I argue that in each case, while Russell accepts views which Dummett attributes to Frege, Frege does not.     

Diagrammatic reasoning in Frege’s Begriffsschrift

In Part III of his 1879 logic Frege proves a theorem in the theory of sequences on the basis of four definitions. He claims in Grundlagen that this proof, despite being strictly deductive, constitutes a real extension of our knowledge, that it is ampliative rather than merely explicative. Frege furthermore connects this idea of ampliative deductive proof to what he thinks of as a fruitful definition, one that draws new lines. My aim is to show that we can make good sense of these claims if we read Frege??s notation diagrammatically, in particular, if we take that notation to have been designed to enable one to exhibit the (inferentially articulated) contents of concepts in a way that allows one to reason deductively on the basis of those contents.     

Second-Order Positive Comprehension and Frege’s Basic Law V

Richard Heck and John Burgess have shown that Frege’s Basic Law V is consistent with predicative comprehension and that the resulting theory interprets Robinson Arithmetic. There are also many other ways to keep Frege from being contradictory. This paper shows that Basic Law V is also consistent with positive comprehension and that the resulting theory also interprets Robinson Arithmetic. In addition, the theory of positive Frege provides a new understanding of Dummett’s “indefinitely extensible concepts.”