Timm Lampert

In his early philosophy as well as in his middle period, Wittgenstein holds a purely syntactic view of logic and mathematics. However, his syntactic foundation of logic and mathematics is opposed to the axiomatic approach of modern mathematical logic. The object of Wittgenstein’s approach is not the representation of mathematical properties within a logical axiomatic system, but their representation by a symbolism that identifies the properties in question by its syntactic features. It rests on his distinction of descriptions and operations; its aim is to reduce mathematics to operations. This paper illustrates Wittgenstein’s approach by examining his discussion of irrational numbers.

This paper illustrates what a philosophical and a logical investigation of colors amounts to in contrast to other kinds of color analysis such as physical, physiological, chemical, psychological or cultural analysis of colors. Neither a philosophical nor a logical analysis of colors is concerned with specific aspects of colors. Rather, these kinds of color analysis are concerned with what one might call “logical foundations of color theory”. I will illustrate this first by considering philosophical and then logical analysis of colors.

This paper describes a decision procedure for disjunctions of conjunctions of anti-prenex normal forms of pure first-order logic (FOLDNFs) that do not contain V within the scope of quantifiers. The disjuncts of these FOLDNFs are equivalent to prenex normal forms whose quantifier-free parts are conjunctions of atomic and negated atomic formulae (= Herbrand formulae). In contrast to the usual algorithms for Herbrand formulae, neither skolemization nor unification algorithms with function symbols are applied. Instead, a procedure is described that rests on nothing but equivalence transformations within pure first-order logic (FOL). This procedure involves the application of a calculus for negative normal forms (the NNF-calculus) with A -||- A & A (= &I) as the sole rule that increases the complexity of given FOLDNFs. The described algorithm illustrates how, in the case of Herbrand formulae, decision problems can be solved through a systematic search for proofs that reduce the number of applications of the rule &I to a minimum in the NNF-calculus. In the case of Herbrand formulae, it is even possible to entirely abstain from applying &I. Finally, it is shown how the described procedure can be used within an optimized general search for proofs of contradiction and what kind of questions arise for a &I-minimal proof strategy in the case of a general search for proofs of contradiction.

This paper systematically outlines Wittgenstein's ab-notation. The purpose of this notation is to provide a proof procedure in which ordinary logical formulas are converted into ideal symbols that identify the logical properties of the initial formulas. The general ideas underlying this procedure are in opposition to a traditional conception of axiomatic proof and are related to Peirce's iconic logic. Based on Wittgenstein's scanty remarks concerning his ab-notation, which almost all apply to propositional logic, this paper explains how to extend his method to a subset of first-order formulas, namely, formulas that do not contain dyadic sentential connectives within the scope of any quantifier.

According to some scholars, such as Rodych and Steiner, Wittgenstein objects to Gödel’s undecidability proof of his formula $$G$$, arguing that given a proof of $$G$$, one could relinquish the meta-mathematical interpretation of $$G$$ instead of relinquishing the assumption that Principia Mathematica is correct. Most scholars agree that such an objection, be it Wittgenstein’s or not, rests on an inadequate understanding of Gödel’s proof. In this paper, I argue that there is a possible reading of such an objection that is, in fact, reasonable and related to Gödel’s proof.

Newton claims to have proven the heterogeneity of light through his experimentum crucis. However, Olaf Müller has worked out in detail Goethe’s idea that one could likewise prove the heterogeneity of darkness by inverting Newton’s famous experiment. Müller concludes that this invalidates Newton’s claim of proof. Yet this conclusion only holds if the heterogeneity of light and the heterogeneity of darkness is logically incompatible. This paper shows that this is not the case. Instead, in Quine’s terms, we have two logically compatible theories based on mutually irreducible theoretical terms. From a Quinean point of view, this does no harm to the provability of the corresponding statements.

This paper discusses a definition of logical validity of arguments that is provided by Christoph Schamberger in his book Logik der Umgangssprache (2016). The paper identifies some problems of the given definition. It argues that any definition reducing the logical validity of ordinary arguments to the logical validity of their formalization does not meet the criteria of non-circularity, unambiguousness, correctness and completeness. Finally, the paper shows that Schamberger’s filter logic brings about that his definition does also not meet the standards of formal precision and explanatory power.

Das Buch entwickelt einen neuartigen, physikalistischen Interpretationsansatz zu Wittgensteins Tractatus Logico-Philosophicus. Das traditionelle Urteil, Wittgenstein habe im Tractatus keine klare Vorstellung der Analyse gehabt, wird widerlegt. Auf der Basis der Rekonstruktion der um die Jahrhundertwende etablierten Sinnesdatenanalysen im allgemeinen und der Farbanalysen im besonderen wird nachgewiesen, daß Wittgensteins Tractatus eine physikalische Sinnesdatenanalyse voraussetzt. Auf diesem Hintergrund werden Wittgensteins allgemeine Auffassungen zur Analyse der Welt und Sprache gedeutet, begründet und exemplifiziert. Der Tractatus liefert die philosophische Klärung des mechanistischen Weltbildes von Boltzmann und Hertz. Er stellt die Mittel bereit, um den Sinn der Sätze zu analysieren und die logische Zulässigkeit von Aussagen zu prüfen. Die Anwendung dieser Mittel ist Aufgabe der Philosophie. Daß sie anwendbar sind und wie sie anzuwenden sind, demonstriert dieses Buch.

This paper argues for a physicalistic interpretation of Wittgenstein's Tractatus Logico-Philosophicus. Wittgenstein's general conception of world and language analysis is interpreted and exemplified in relation to the historical background of the psychophysical analysis of sense data and, in particular, color analysis. Three of his main principles of analysis—the principle of independence, the context principle and the principle of atomism—are interpreted and justified on the background of physicalism. From his proof of color exclusion in the Tractatus, it is shown that Wittgenstein had a detailed conception of how philosophy should fulfil the task of distinguishing between sense and nonsense using physicalistic presuppositions

Paul Engelmann hat über zwanzig Jahre seines Lebens an einer systematischen Darstellung der Psychologie mittels einer von ihm entwickelten graphischen Methode gearbeitet. Das Resultat dieser Arbeit bildet seine Psychologie graphisch dargestellt, die sich in seinem Nachlaß befindet. In diesem Werk will Engelmann die Klärung geistiger Aufgabengebiete, wie sie seine Lehrer Karl Kraus, Adolf Loos und Ludwig Wittgenstein betrieben haben, in der Psychologie fortsetzen. Hierbei fiihrt er Freuds Methode weiter, psychische Erscheinungen räumlich darzustellen, und wendet die Bildtheorie Wittgensteins auf seine Theorie psychischer Vorgänge an.