In contemporary historical studies, Peano is usually included in the logical tradition pioneered by Frege. In this paper, I shall first demonstrate that Frege and Peano independently developed a similar way of using logic for the rigorous expression and proof of mathematical laws. However, I shall then suggest that Peano also used his mathematical logic in such a way that anticipated a formalisation of mathematical theories which was incompatible with Frege’s conception of logic.

Before Frege, the term Begriffsschrift'was used to indicate a language the expressions of which adequately represent the structure of the judgements or concepts which they signify, and a language the written signs of which designate ideas rather than sounds. In 1879 Frege follows . Later he adopts —and with it the Aristotelian theory of language in which it is embedded.

Before Frege, the term Begriffsschrift'was used to indicate a language the expressions of which adequately represent the structure of the judgements or concepts which they signify, and a language the written signs of which designate ideas rather than sounds. In 1879 Frege follows. Later he adopts —and with it the Aristotelian theory of language in which it is embedded.

Well over a century after its introduction, Frege's two-dimensional Begriffsschrift notation is still considered mainly a curiosity that stands out more for its clumsiness than anything else. This paper focuses mainly on the propositional fragment of the Begriffsschrift, because it embodies the characteristic features that distinguish it from other expressively equivalent notations. In the first part, I argue for the perspicuity and readability of the Begriffsschrift by discussing several idiosyncrasies of the notation, which allow an easy conversion of logically equivalent (...) formulas, and presenting the notation's close connection to syntax trees. In the second part, Frege's considerations regarding the design principles underlying the Begriffsschrift are presented. Frege was quite explicit about these in his replies to early criticisms and unfavorable comparisons with Boole's notation for propositional logic. This discussion reveals that the Begriffsschrift is in fact a well thought-out and carefully crafted notation that intentionally exploits the possibilities afforded by the two-dimensional medium of writing like none other. (shrink)

It has been noted before in the history of logic that some of Frege's logical and semantic views were anticipated in Stoicism. In particular, there seems to be a parallel between Frege's Gedanke (thought) and Stoic lekton; and the distinction between complete and incomplete lekta has an equivalent in Frege's logic. However, nobody has so far claimed that Frege was actually influenced by Stoic logic; and there has until now been no indication of such a causal connection. In this essay, (...) we attempt, for the first time, to provide detailed evidence for the existence of this connection. In the course of our argumentation, further analogies between the positions of Frege and the Stoics will be revealed. The classical philologist Rudolf Hirzel will be brought into play as the one who links Frege with Stoicism. The renowned expert on Stoic philosophy was Frege's tenant and lived in the same house as the logician for many years. In der Geschichte der Logik ist häufig bemerkt worden, dass einige der logischen und semantischen Auffassungen Freges in der Stoa antizipiert worden sind. Genannt wurden insbesondere die Parallelen zwischen dem Fregeschen Gedanken und dem stoischen Lekton sowie die Unterscheidung zwischen vollständigen und unvollständigen Lekta, die bei Frege ihre Entsprechung hat. Ein Wirkungszusammenhang ist allerdings nicht behauptet worden. Dazu gab es bislang auch keinen Anlass. Der vorliegende Beitrag versucht erstmalig, einen detaillierten Indizienbeweis für das Bestehen eines solchen Zusammenhangs vorzulegen. Dabei werden weitere charakteristische Übereinstimmungen zwischen Frege und der Stoa aufgewiesen. Als Mittelsmann wird der Altphilologe Rudolf Hirzel vorgestellt. Er wohnte lange Jahre als Mieter zusammen mit Frege im selben Haus und war ein anerkannter Experte der stoischen Philosophie. (shrink)

Frege's main contributions to logic and the philosophy of mathematics are, on the one hand, his introduction of modern relational and quantificational logic and, on the other, his analysis of the concept of number. My focus in this paper will be on the latter, although the two are closely related, of course, in ways that will also play a role. More specifically, I will discuss Frege's logicist reconceptualization of the natural numbers with the goal of clarifying two aspects: the motivations (...) for its core ideas; the step-by-step development of these ideas, from Begriffsschrift through Die Grundlagen der Arithmetik and Grundgesetze der Arithmetik to Frege's very last writings, indeed even beyond those, to a number of recent "neo-Fregean" proposals for how to update them. One main development, or break, in Frege's views occurred after he was informed of Russell's antinomy. His attempt to come to terms with this antinomy has found some attention in the literature already. It has seldom been analyzed in connection with earlier changes in his views, however, partly because those changes themselves have been largely ignored. Nor has it been discussed much in connection with Frege's basic motivations, as formed in reaction to earlier positions. Doing both in this paper will not only shed new light on his response to Russell's antinomy, but also on other aspects of his views. In addition, it will provide us with a framework for comparing recent updates of these views, thus for assessing the remaining attraction of Frege's general approach. I will proceed as follows: In the first part of the paper (§1.1 and §1.2), I will consider the relationship of Frege's conception of the natural numbers to earlier conceptions, in particular to what I will call the "pluralities conception", thus bringing into sharper focus his core ideas and their motivations. In the next part (§2.1 and §2.2), I will trace the order in which these ideas come up in Frege's writings, as well as the ways in which his position gets modified along the way, both before and after Russell's antinomy.. (shrink)

[ES] Gottlob Frege posiblemente era el primer filósofo analítico. La exégesis de su doctrina quedó durante varias décadas restringida casi naturalmente al ámbito de la filosofía analítica y angloparlante. El método que Frege heredó a la filosofía analítica se basa en el análisis abstracto y formal, y la aprehensión de su doctrina se desarrolló bajo el supuesto –tomado casi por autoevidente- que éste método es el único correcto para dar cuenta de los problemas filosóficos más fundamentales, muy particularmente el de (...) desarrollar una teoría de significado. Igualmente se asumía y asume todavía con cierto automatismo que las preocupaciones filosóficas de Frege son fundamentalmente las mismas de la filosofía analítica y las que no caben en este supuesto se desechan fácilmente como anacrónicas o absurdas. Este acercamiento al pensamiento de Frege exclusivamente bajo los supuestos de la filosofía analítica, sus méritos no obstante, no toma en cuenta el ambiente anti-naturalista y neo-kantiano en el cual Frege formó sus convicciones fundamentales. Algunos aspectos contenciosos como, por ejemplo, el principio de contexto, una posible jerarquía de sentidos indirectos o la suposición, casi tácita, de que la doctrina de Frege es una teoría sobre expresiones referenciales, aparecen en una luz diferente si nos damos cuenta de que su intento de construir un sistema es, en cuanto a filosofía, en el fondo una respuesta a problemas que Frege encontró en el sistema de Kant. [EN] Gottlob Frege was quite possibly the first analytical philosopher. For several decades the study of his teachings restricted itself almost naturally to the sphere of analytical and English speaking philosophy. The very method which Frege might have impressed upon analytical philosophy takes off with abstract and formal analysis and the apprehension of his doctrine developed under the assumption –taken to be almost self-evident- that this method is the only one capable of correctly accounting for the most fundamental philosophical problems, especially bringing forth a comprehensive theory of meaning. Hence it was taken for granted with certain automatism that the Frege´s philosophical worries were initially identical in its origins with those of contemporary analytical philosophy and those not amenable to easy adoptions are discharged as absurd anachronisms when viewed against current doctrines. Approaching Fregean thought exclusively under the assumptions of analytical philosophy, while having merit, does not take into account the anti-naturalist and neo-Kantian background which influenced the modelling of Frege’s fundamental convictions. Some contentious aspects like for example the context principle, a possible hierarchy of indirect senses or the almost tacit assumption that Frege’s doctrine is a theory about referential expressions appear in a different light, once we become aware that his attempt at system-construction, as far as it concerns philosophy, is fundamentally an answer to problems which Frege found in Kant’s system. (shrink)

It has been noted before in the history of logic that some of Frege's logical and semantic views were anticipated in Stoicism. In particular, there seems to be a parallel between Frege's Gedanke (thought) and Stoic lekton; and the distinction between complete and incomplete lekta has an equivalent in Frege's logic. However, nobody has so far claimed that Frege was actually influenced by Stoic logic; and there has until now been no indication of such a causal connection. In this essay, (...) we attempt, for the first time, to provide detailed evidence for the existence of this connection. In the course of our argumentation, further analogies between the positions of Frege and the Stoics will be revealed. The classical philologist Rudolf Hirzel will be brought into play as the one who links Frege with Stoicism. The renowned expert on Stoic philosophy was Frege's tenant and lived in the same house as the logician for many years. In der Geschichte der Logik ist häufig bemerkt worden, dass einige der logischen und semantischen Auffassungen Freges in der Stoa antizipiert worden sind. Genannt wurden insbesondere die Parallelen zwischen dem Fregeschen Gedanken und dem stoischen Lekton sowie die Unterscheidung zwischen vollständigen und unvollständigen Lekta, die bei Frege ihre Entsprechung hat. Ein Wirkungszusammenhang ist allerdings nicht behauptet worden. Dazu gab es bislang auch keinen Anlass. Der vorliegende Beitrag versucht erstmalig, einen detaillierten Indizienbeweis für das Bestehen eines solchen Zusammenhangs vorzulegen. Dabei werden weitere charakteristische Übereinstimmungen zwischen Frege und der Stoa aufgewiesen. Als Mittelsmann wird der Altphilologe Rudolf Hirzel vorgestellt. Er wohnte lange Jahre als Mieter zusammen mit Frege im selben Haus und war ein anerkannter Experte der stoischen Philosophie. (shrink)

The paper analyses Frege's approach to the identity conditions for the entity labelled by him as Sinn. It starts with a brief characterization of the main principles of Frege's semantics and lists his remarks on the identity conditions for Sinn. They are subject to a detailed scrutiny, and it is shown that, with the exception of the criterion of intersubstitutability in oratio obliqua, all other criteria have to be discarded. Finally, by comparing Frege's views on Sinn with Carnap's method of (...) extension and intension and the method of intensional isomorphism, it is proved that these methods do not provide a criterion for the identity of Frege's Sinn, even for extensional contexts, that the concept of intension does not coincide, as stated by Carnap, in these contexts, with Frege's concept of Sinn, and that Carnap's claim that in oratio obliqua Frege's semantics leads to an infinite hierarchy of Sinn entities can be questioned at least hypothetically in the light of certain new historical facts. (shrink)