• Journal for History of Mathematics
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• v.13 no.2
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• pp.145-150
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• 2000

This paper is intended to show that fuzzy logic can be understood in the context of the late Wittgenstein's philosophy. It introduces the view of language presupposed by fuzzy logic and parallels it with the late Wittgenstein's view of language. To make the parallel clear it contrasts the views of the early Wittgenstein and the late Wittgenstein.

• Korean Journal of Logic
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• v.15 no.1
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• pp.155-190
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• 2012

As far as Hilbert's Program is concerned, there seems to be important differences in the development of Wittgenstein's thoughts. Wittgenstein's main claims on this theme in his middle period writings, such as Wittgenstein and the Vienna Circle, Philosophical Remarks and Philosophical Grammar seem to be different from the later writings such as Wittgenstein's Lectures on the Foundations of Mathematics (Cambridge 1939) and Remarks on the Foundations of Mathematics. To show that differences, I will first briefly survey Hilbert's program and his philosophy of mathematics, that is to say, formalism. Next, I will illuminate in what respects Wittgenstein was influenced by and criticized Hilbert's formalism. Surprisingly enough, Wittgenstein claims in his middle period that there is neither metamathematics nor proof of consistency. But later, he withdraws his such radical claims. Furthermore, we cannot find out any evidences, I think, that he maintained his formerly claims. I will illuminate why Wittgenstein does not raise such claims any more.

• Korean Journal of Logic
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• v.19 no.2
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• pp.253-293
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• 2016

In Wittgenstein's Tractatus, the concept of 'identity' gives rise to several puzzles as follows. What is an equation(Gleichung) in the Tractatus? Is an equation identical with so called an identity statement? Frege asserts that identity is not a relation between signs but one between objects or of a thing to itself. Then how does Wittgenstein criticize this Frege's conception? Furthermore Wittgenstein explicitly criticizes about Russell's definition of identity. Then What is the point of such Wittgenstein's critique? In a nutshell, what is early Wittgenstein's idea on the nature of identity? In this paper, I will endeavor to answer these questions.

• Korean Journal of Logic
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• v.20 no.1
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• pp.69-96
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• 2017

Wittgenstein criticizes explicitly Russell's theory of types and, in particular, his axiom of reducibility in the Tractatus Logico-Philosophicus. What, then, is the point of Wittgenstein's criticisms of Russell's theory of types? As a preliminary study to answer this question, I will examine how Wittgenstein criticized Russell's axiom of reducibility. Wittgenstein declares that Russell's axiom of reducibility is not a logical proposition, that if it is true it will be so mere by a happy chance and that "we can imagine a world in which the axiom of reducibility is not valid." What, then, is the ground for that? I will endeavor to show that by explicating the ideas of Wittgenstein's 1913 letter to Russell, those ideas decisively influenced on Ramsey's and Waismann's model which intended to show that the axiom of reducibility is not valid.

• Korean Journal of Logic
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• v.21 no.1
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• pp.1-37
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• 2018

As is well known, Wittgenstein criticizes Russell's theory of types explicitly in the Tractatus. What, then, is the point of Wittgenstein's criticism of Russell's theory of types? In order to answer this question I will consider the theory of types on its philosophical aspect and its logical aspect. Roughly speaking, in the Tractatus Wittgenstein's logical syntax is the alternative of Russell's theory of types. Logical syntax is the sign rules, in particular, formation rules of notation of the Tractatus. Wittgenstein's distinction of saying-showing is the most fundamental ground of logical syntax. Wittgenstein makes a step forward with his criticism of Russell's theory of types to the view that logical grammar is arbitrary and a priori. His criticism of Russell's theory of types is after all the challenge against Frege-Russell's conception of logic. Logic is not concerned with general truth or features of the world. Tautologies which consist of logic say nothing.

• Korean Journal of Logic
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• v.16 no.3
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• pp.309-346
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• 2013

This paper deals with the problem, which logic of language and which metaphysics Wittgenstein suggests in the Tractatus logico-philosophicus. I will ultimately show how he bases the metaphysics on the logic of language. The logic of language by which Wittgenstein sets the limit to the language 'in the language' is the logical syntax of the language. And Wittgenstein extends the idea of the logical syntax to the understanding the nature of the world, i.e. to the metaphysics. The logical form the language(proposition) must have is the form of the world(or the nature of the world), and it can be determined only together with the logical syntax of the language. But what is the logical form(form of the world) 'cannot be said', since the proposition saying it is devoid of 'sense' and 'says nothing'. Therefore Wittgenstein expresses that the logical form(form of the world) 'can only be shown' in the proposition that has sense. The Metaphysics Wittgenstein wants to base on the logic of language(the logical syntax) must be mystical.

• Korean Journal of Logic
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• v.19 no.1
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• pp.49-82
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• 2016

In this paper, I argue that it is Kripke's Tractarian notion of rule-following that prevents him from giving a non-skeptical (straight) solution to Wittgenstein's paradox. I characterize the Tractarian notion of rule-following as the 'determinate/infinistic' notion of rule-following. The later Wittgenstein, however, advocates an opposite notion of rule-following: the 'indeterminate/finistic' notion. Considering the later Wittgenstein's context-sensitive, pragmatics-oriented approach to meaning and rule-following, the later Wittgenstein could not have endorsed the determinate/infinistic notion of rule-following. To the contrary, a motive behind Wittgenstein's skeptical paradox was to blame the Tractarian notion of rule-following as the major culprit giving rise to the paradox. At the end, I argue that Kripke's adherence to the Tractarian-correspondence theory of truth also contributes to his failure to offer a non-skeptical solution to the paradox. If Kripke had noticed that the later Wittgenstein was a deflationist about truth, he could have avoided his skeptical conclusion.

• Korean Journal of Logic
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• v.13 no.1
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• pp.83-100
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• 2010

In his recent paper "Early Wittgenstein, Logic, and Metaphysics" Professor Jinho Kang argues that there has been an important change in Wittgenstein's view on the nature of logic between October 1913 and December 1916, which resulted in his change of attitude toward metaphysics. In my paper, raising some questions regarding his basic assumptions and arguments, I attempt to show that Professor Kang's paper fails to provide convincing solution to the points at issue.

• Korean Journal of Logic
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• v.20 no.2
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• pp.163-196
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• 2017

Wittgenstein declares in the Tractatus Logico-Philosophicus that he resolved Russell's Paradox. According to him, a function cannot be its own argument. If we assume that a function F(fx) can be its own argument, a proposition "F(F(fx))" will be given, where the outer function F has a meaning different from the inner function F. In consequence, "F(F(fx))" will not be able to have a definite sense. Why, however, does Wittgenstein call into question a function F(fx) and "F(F(fx))"? To answer this question, we must examine closely Russell's own resolution of Russell's Paradox. Only when we can understand Russell's resolution can we do Wittgenstein's resolution. In particular, I will endeavor to show that the idea in Wittgenstein's 1913 letter to Russell provides a decisive clue for this problem.

• Korean Journal of Logic
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• v.16 no.3
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• pp.347-380
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• 2013

In this paper I will try to show how Wittgenstein criticized Frege's theory of meaning. Frege's theory of meaning can be compressed as sense-reference theory. Frege distinguishes between sense and reference on all the linguistic expressions. In particular, he regards that a sentence has sense and reference. This distinction was raised from, so to speak, the problem of identity sentences. Wittgenstein's "fundamental thought" of Tractatus Logico-Philosophicus is the key of his direct criticism of Frege's sense-reference theory. That is, it is an attack on Frege's thought that the reference of a sentence is a truth value and truth values are "objects themselves" (in Frege's meaning). According to Wittgenstein, such an object does not exist and according to his picture theory, the function of a name and that of a proposition are fundamentally different. By the way, Frege can reply justly to this criticism that it is insufficient. In short, Frege's 'sense' and 'reference' etc, are the technical terms. Hence Wittgenstein's decisive criticism of Frege's theory consists in accusing his theory of logical flaws. There is an another route to the sense and reference of a sentence which Frege introduces. In discourses of judgement stroke and content stroke in his Begriffsshrift and in those of horizontal stroke since his "Function and Concept", Frege deals with the sense and reference of a sentence. Wittgenstein criticize that the sense of a complex sentence such as ~p would by no means be determined by Frege's determination.