Frege's essay "Der Gedanke.Eine logische Untersuchung" was first published in the Beitrage zur Philosophie des Deutschen Idealismus for 1918-1919 and is one of three related logical studies published as a complete work by Gunther Patzig entitled Logische Untersuchungen in Gottingen, 1966 .

This work addresses the critical discussion featured in the contemporary literature about two well-known paradoxes belonging to different philosophical traditions, namely Frege’s puzzling claim that “the concept horse is not a concept” and Gongsun Long’s “white horse is not horse”. We first present the source of Frege’s paradox and its different interpretations, which span from plain rejection to critical analysis, to conclude with a more general view of the role of philosophy as a fight against the misunderstandings that (...) come from the different uses of language (a point later developed by the “second” Wittgenstein). We then provide an overview of the ongoing discussions related to the Bai Ma Lun paradox, and we show that its major interpretations include—as in the case of Frege’s paradox—dismissive accounts that regard it as either useless or wrong, as well as attempts to interpret and repair the argument. Resting on our reading of Frege’s paradox as an example of the inescapability of language misunderstandings, we advance a similar line of interpretation for the paradox in the Bai Ma Lun: both the paradoxes, we suggest, can be regarded as different manifestations of similar concerns about language, and specifically about the difficulty of referring to concepts via language. (shrink)

كان «فريجه» – على حد تعبير «دامت» – من أوائل من أدركوا أن نظرية المعنى، أو فلسفة اللغة، هي جزءٌ اساسي من الفلسفة ترتكز عليه كافة الأجزاء الاخرى؛ فإلى جانب دراساته التأسيسية الرائدة في الرياضيات والمنطق، كان يُؤسس ايضًا لفلسفة اللغة ببعض المقالات التي فاقت في تاثيرها وشهرتها تاثير وشهرة معظم أعماله الرياضية الأخرى، دون إقلال من شان هذه الأخيرة وريادتها. وهذه الدراسة بمثابة قراءة تحليلية – نقدية لمقاله الأكثر أهمية في هذا الصدد «في المعنى والإشارة»، مشفوعة بترجمة إلى العربية (...) للجزء الأكبر والاهم منه. (shrink)

A summary of the philosophical career and intellectual contributions of Gottlob Frege (1848–1925), including his invention of first- and second-order quantified logic, his logicist understanding of arithmetic and numbers, the theory of sense (Sinn) and reference (Bedeutung) of language, the third-realm metaphysics of “thoughts”, his arguments against rival views, and other topics.

Gottlob Frege (1848-1925) has been called ‘the undisputed father of analytic philosophy’ and ‘the most important logician since Aristotle.’ Even if his impact on philosophy were to extend no further than his decisive influence on leading early twentieth-century thinkers of the stature of Bertrand Russell, Ludwig Wittgenstein and Rudolf Carnap, that alone would assure him a notable place in the history of modern philosophy. Nevertheless, there are other areas of Frege’s intellectual activity that have largely escaped the (...) attention of his commentators. One of these is his seldom-noticed attempt late in life to write about political theology. In this reconstruction of Frege’s view, based on a context-sensitive close reading of his fragmentary writing on theology, I document Frege’s commitment to a highly politicized conception of theology’s public role. This conception is infused with the ideology of Germany’s Far-Right völkisch (pan-German ethnic-nationalist) movement and steeped in the political strife of early Weimar-era Germany. Frege’s interest in theology was evidently rooted not so much in conventionally spiritual concerns as in the decidedly innerweltlich desire to help turn the tide in German politics in favor of the ultranationalist Far Right. His theology was, accordingly, a political theology of völkisch, antisemitic, and anti-socialist nationalism. (shrink)

This paper presents a passage on truth from "Der Gedanke" and comments on its content and use in the classroom.

In this dissertation I offer a global and detailed reconstruction of the logic developed by Gottlob Frege throughout his career. Even though Frege's logic suffered profound modifications from his initial formulation in Begriffsschrift to its revised version in Grundgesetze, the significant differences between these two works have been rarely taken at face value. I not only argue that these differences exist, but I also explain how they should be understood in the light of the evolution of (...) class='Hi'>Frege's thought. First, I suggest a new reconstruction of Begriffsschrift's logic, which amounts to a completely novel reading of its formal system—one that contradicts the core of modern historical studies. In particular, I defend that this logic is not—as it has been repeatedly said—a second-order logic and provide the following reasons. (1) The language is not properly a formal language. (2) In Begriffsschrift there is only one sort of quantification: quantification over arguments. (3) Begriffsschrift's logic does not have a semantics in the modern sense. Second, I offer an explanation of the reasons that drive the evolution of Frege's logic. The transition from Begriffsschrift to Grundgesetze has been seldom addressed and never fully explained. According to my historical analysis, the switch from Frege's position concerning logic in Begriffsschrift to his later conception—finally established in Grundgesetze—can be articulated through the adoption of the distinction between concept and object as the basic element of the formal system. This leads to a formalisation of the notion of concept, which in the end drives to Grundgesetze's notion of function. Finally, I put forward a global analysis of Grundgesetze's logic. In this work, Frege develops a formal system that resembles in many relevant ways a second-order one. I suggest a reconstruction of this formal system that allows us to compare it with Begriffsschrift's. In particular, I formulate precisely every rule of inference proposed by Frege and especially focus on the rules of substitution. Moreover, I reflect on several meta-logical results that can be drawn from this reconstruction. (shrink)

El presente texto es una guía para una primera lectura de los Los fundamentos de la aritmética de Gottlob Frege para estudiantes del grado de Filosofía. -/- No pretende hacer ninguna aportación a la investigación sobre Frege sino ofrecer los instrumentos para hacer una primera lectura mediante la recopilación y la ordenación de los textos relevantes de los estudiosos de Frege, especialmente de la literatura en inglés. En la mayor parte de los casos, las referencias a (...) otros autores (Autorfecha) preceden a una traducción de los escritos referidos así como una unificación de la terminología, el recorte de lo no relevante y el añadido de las explicaciones pertinentes para hacer el texto accesible a un estudiante del grado de Filosofía. En el caso de que la cita justifique una afirmación que no se desarrolla, se verá precedida por la palabra "ver" dentro del paréntesis de la referencia. El texto usado para las citas de Los fundamentos de la aritmética es la traducción de Ulises Moulines dado que el que esto escribe no sabe alemán. La guía no supone más matemáticas que las que se estudian en los cursos anteriores a la universidad. Sin embargo, es recomendable haber hecho un curso elemental de lógica matemática y teoría de conjuntos. La razón fundamental es que la formalización de ciertas proposiciones permite aclarar extremos que se hacen muy enojosos sin esos instrumentos. (shrink)

The present article reviews the Polish-language edition of Gottlob Frege’s scientific correspondence. In the article, I discuss the material hitherto unpublished in Polish in relation to the remainder of Frege’s works. First of all, I inquire into the role and nature of definitions. Then, I consider Frege’s recognition criteria for sameness of thoughts. In the article’s third part, I study letters devoted to the principle of semantic compositionality, while in the fourth part I discuss Frege’s (...) remarks concerning the context principle. (shrink)

El presente artículo tiene como principal objetivo introducir al lector algunos de los conceptos fundamentales de la filosofía de Gottlob Frege. Estos son: el binomio sentido/referencia, el valor veritativo de oraciones con elementos no referenciales, la distinción entre pensar, juzgar y aseverar, su concepción de los indéxicos y los demostrativos, así como su defensa de la existencia de un tercer reino. En algunos de ellos se mostrarán algunas problemáticas asociadas que han sido destacados por pensadores de renombre. Tal (...) es el caso, por ejemplo, de la famosa crítica de Bertrand Russell a la semántica de Frege por su incapacidad para dar cuenta del valor de verdad de oraciones ficticias. Dirigido especialmente al lector lego en la materia, aunque sin perder rigor académico, este trabajo procura presentar algunas de las principales tesis fregeanas a través de sus fuentes primarias. (shrink)

Review of Basic Laws of Arithmetic, ed. and trans. by P. Ebert and M. Rossberg (Oxford 2013).

Frege says, at the end of a discussion of formalism in the Foundations of Arithmetic, that his own foundational program “could be called formal” but is “completely different” from the view he has just criticized. This essay examines Frege’s relationship to Hermann Hankel, his main formalist interlocutor in the Foundations, in order to make sense of these claims. The investigation reveals a surprising result: Frege’s foundational program actually has quite a lot in common with Hankel’s. This undercuts (...) Frege’s claim that his own view is completely different from Hankel’s formalism, and motivates a closer examination of where the differences lie. On the interpretation offered here, Frege shares important parts of the formalist perspective, but differs in recognizing a kind of content for arithmetical terms which can only be made available via proof from prior postulates. (shrink)

This chapter explores the metaphysical views about higher-order logic held by two individuals responsible for introducing it to philosophy: Gottlob Frege (1848–1925) and Bertrand Russell (1872–1970). Frege understood a function at first as the remainder of the content of a proposition when one component was taken out or seen as replaceable by others, and later as a mapping between objects. His logic employed second-order quantifiers ranging over such functions, and he saw a deep division in nature between (...) objects and functions. Russell understood propositional functions as what is obtained when constituents of propositions are replaced by variables, but eventually denied that they were entities in their own right. Both encountered contradictions when supposing there to exist as many objects as functions, and both adopted views about the meaningfulness of higher-order discourse that were difficult to state from within their own strictures. (shrink)

This paper argues that Frege's notoriously long commitment to Kant's thesis that Euclidean geometry is synthetic _a priori_ is best explained by realizing that Frege uses ‘intuition’ in two senses. Frege sometimes adopts the usage presented in Hermann Helmholtz's sign theory of perception. However, when using ‘intuition’ to denote the source of geometric knowledge, he is appealing to Hermann Cohen's use of Kantian terminology. We will see that Cohen reinterpreted Kantian notions, stripping them of any psychological connotation. (...) Cohen's defense of his modified Kantian thesis on the unique status of the Euclidean axioms presents Frege's own views in a much more favorable light. (shrink)

This book aims to develop certain aspects of Gottlob Frege’s theory of meaning, especially those relevant to intensional logic. It offers a new interpretation of the nature of senses, and attempts to devise a logical calculus for the theory of sense and reference that captures as closely as possible the views of the historical Frege. (The approach is contrasted with the less historically-minded Logic of Sense and Denotation of Alonzo Church.) Comparisons of Frege’s theory with those (...) of Russell and others are given. It is in the end shown that developing Frege’s theory in these ways reveals serious problems hitherto largely unnoticed, including those possibly rendering a Fregean intensional logic inconsistent even if his naïve class theory is excluded. (shrink)

Gottlob Frege maintained that two name-containing identity sentences, represented schematically as a=a and a=b,can both be true in virtue of the same object’s self-identity but nonetheless, puzzlingly, differ in their epistemic profiles. Frege eventually resolved his puzzlement by locating the source of the purported epistemic difference between the identity sentences in a difference in the Sinne, or senses, expressed by the names that the sentences contain. -/- Thus, Frege portrayed himself as describing a puzzle that can (...) be posed prior to and independently of any particular theoretical position regarding names, and then resolving that puzzle with his theory of Sinn and Bedeutung. In this paper, I suggest that Frege’s presentation is problematic. If attempt is made to characterize the epistemic status of true identity sentences without appeal to Frege’s theoretical commitments, then what initially seemed puzzling largely dissolves. It turns out that, in order to generate puzzlement, Frege must invoke the theoretical account that he uses the puzzle to establish the purported necessity of. (shrink)

Gottlob Frege and Ludwig Wittgenstein (the later Wittgenstein) are often seen as polar opposites with respect to their fundamental philosophical outlooks: Frege as a paradigmatic "realist", Wittgenstein as a paradigmatic "anti-realist". This opposition is supposed to find its clearest expression with respect to mathematics: Frege is seen as the "arch-platonist", Wittgenstein as some sort of "radical anti-platonist". Furthermore, seeing them as such fits nicely with a widely shared view about their relation: the later Wittgenstein is supposed (...) to have developed his ideas in direct opposition to Frege. The purpose of this paper is to challenge these standard assumptions. I will argue that Frege's and Wittgenstein's basic outlooks have something crucial in common; and I will argue that this is the result of the positive influence Frege had on Wittgenstein. (shrink)

Gottlob Frege criticized Kant's use of the term "representation" in a footnote in the Foundations of Arithmetics. According to Frege, Kant used the term "representation" for mental images, which are private and incommunicable, and also for objects and concepts. Kant thereby gave "a strongly subjectivistic and idealistic coloring" to his thought. The paper argues that Kant avoided the kind of subjectivism and idealism which Frege hints in his remark. For Kant, having "Vorstellungen" requires the capacity of (...) synthesis, by virtue of which the mind goes beyond its subjective states, and its modifications become presentations of an independent world. (shrink)

A presentation and discussion of Gottlob Frege's understanding of language, both natural and artificial, with close attention to his texts.

Mathematical formalism is the the view that numbers are "signs" and that arithmetic is like a game played with such signs. Frege's colleague Thomae defended formalism using an analogy with chess, and Frege's critique of this analogy has had a major influence on discussions in analytic philosophy about signs, rules, meaning, and mathematics. Here I offer a new interpretation of formalism as defended by Thomae and his predecessors, paying close attention to the mathematical details and historical context. I (...) argue that for Thomae, the formal standpoint is an _algebraic perspective_ on a domain of objects, and a "sign" is not a linguistic expression or mark, but a representation of an object within that perspective. Thomae exploits a shift into this perspective to give a purely algebraic construction of the real numbers from the rational numbers. I suggest that Thomae's chess analogy is intended to provide a model for such shifts in perspective. (shrink)

I investigate why Frege rejected the theory of types, as Russell presented it to him in their correspondence. Frege claims that it commits one to violations of the law of excluded middle, but this complaint seems to rest on a dogmatic refusal to take Russell’s proposal seriously on its own terms. What is at stake is not so much the truth of a law of logic, but the structure of the hierarchy of the logical categories, something Frege (...) seems to neglect. To come to a better understanding of Frege’s response, I proceed to investigate his conception of the nature of the logical categories, and how it differs from Russell’s. I argue that, for Frege, our grasp of the logical categories cannot be severed from our grasp of the Begriffsschrift notation itself. Russell, on the other hand, attaches no such importance to notation. From Frege’s point of view, Russell has not succeeded in presenting an alternative conception of the logical hierarchy, since such a conception must go in tandem with the development of a notation. Moreover, Frege has good reasons to think that Russell’s proposal does not admit of a suitable notation. (shrink)

Gottlob Frege’s conception of works of art has received scant notice in the literature. This is a pity since, as this paper undertakes to reveal, his innovative philosophy of language motivated a theoretically and historically consequential, yet unaccountably marginalized Wittgenstinian line of inquiry in the domain of aesthetics. The element of Frege’s approach that most clearly inspired this development is the idea that only complete sentences articulate thoughts and that what sentences in works of drama and literary (...) art express are ‘mock thoughts’ (Schiengedanken). The early Wittgenstein closely followed Frege’s lead on this theme. One sees this, for example, in the Tractatus, where Wittgenstein announces that only sentential propositions model (‘picture’) states of affairs whereas works of art are objects we perceive sub specie aeternitatis (1961, 83). By the 1930s, however, Wittgenstein began to revise his view beyond his initial Frege-inspired standpoint. He came to insist that works of art can convey thoughts as well, but that thoughts do not model (picture) the world of facts and hence do not convey information about measurable objects and events. Rather, his contention was that aesthetically configured thoughts that artworks communicate impart information about our perspective on reality and reconfigure our view of life. To be more explicit, successful (gelungene) or ‘good’ works of art (ibid.), in Wittgenstein’s view, can supply aesthetically instructive ‘gestures’ that open to living experience promising new ways of being. It is in this respect, he held, that artists ‘have something to teach’ (1980, 36). (shrink)

Husserl and Frege reject logical psychologism, the view that logical laws are psychological 'laws of thought'. This paper offers an account of these famous objections and argues that their crucial premise, the necessity of logical laws, is justified with reference to a problematic metaphysics. However, this premise can be established in a more plausible way, namely via a transcendental argument which starts from the practice of rational criticism. This argument is developed through a discussion of Quine's holism, which at (...) first appears to make the idea of the necessity of logical laws even less plausible, but eventually turns out to speak in favor of this view. (shrink)

I present the replies that Gottlob Frege, Henri Poincaré, Rudolf Carnap, and Saul Kripke made to the assumption that apriority and necessity are interchangeable synonyms, an assumption that I take, together with the assumptions that there is a split between analytic truths and synthetic truths and that there is a dichotomy between our conceptual schemes and empirical content, as a Kantian dogma.

Frege's conception of the logical categories has vexed commentators for decades. In this dissertation, I argue that it revolves around two forms of internality. The first is the internality of its use in the expression of judgment to the sign. A proper understanding of that internality reveals how Frege's philosophical logic cannot be fit into the framework given by the contemporary syntax/semantics distinction. The second is the internality that obtains between the way in which Begriffsschrift signs stratify into (...) different categories, on the one hand, and the way in which the realm of Bedeutungen stratifies into logical categories, on the other hand. A proper understanding of this internality reveals how Frege's conception of the relation between language and the world is neither a form of realism nor a form of linguistic idealism. To come to understand Frege's conception of the logical categories, is to come to understand both these forms of internality by coming to understand how they hang together. (shrink)

É bem conhecida a divergência entre as posições de Gottlob Frege e Bertrand Russell com relação ao tratamento semântico dado a sentenças contendo termos singulares indefinidos, ou seja, termos singulares sem referência ou com referência ambígua, tais como ‘Papai Noel’ ou ‘o atual rei da França’ ou ‘1/0 ’ ou ‘√4’ ou ‘o autor de Principia Mathematica’. Para Frege, as sentenças da linguagem natural que contêm termos indefinidos não formam declarações e portanto não são nem verdadeiras nem (...) falsas. Já para as sentenças da matemática, Frege defende que elas precisam ser corrigidas através da convenção forçada de uma referência não ambígua. Russell, por outro lado, aceita os termos indefinidos e propõe, através de sua teoria das descrições definidas, uma maneira de avaliar as sentenças em que eles ocorrem; e Quine amplia a teoria de Russell para abranger também os nomes com problemas de referência. Na prática da matemática são comuns os termos singulares indefinidos, sem referência, tais como ‘1/0 ’, ou com referência ambígua, tais como ‘√4’. Apesar de não haver uma sistematização rigorosa desta situação entre os matemáticos, há, no entanto, um conjunto de regras convencionais que tradicionalmente costumam ser aplicadas no tratamento matemático dos termos indefinidos. Nossa proposta é tomar a convenção matemática como inspiração e modelo para apresentar uma interpretação semântica formal para as descrições definidas e os nomes e utilizá-la como um argumento que favorece a abordagem de Russell relativamente à de Frege. (shrink)

Gottlob Frege sostuvo que las palabras-concepto sólo se refieren a conceptos no a objetos y que los términos singulares se refieren sólo a objetos no a conceptos. Estas tesis dan lugar a la paradoja del concepto, de acuerdo con la cual ‘el concepto F’ no se refiere a ningún concepto. Mark Textor sostiene que su principio del espejar explica el origen del problema. Sin embargo, argumento que su artículo no explica todas las consecuencias de las tesis de (...) class='Hi'>Frege y mi supuesto semántico ontológico puede verse como una consecuencia del principio del espejar de Textor. (shrink)

O presente artigo busca debater a posição de Charles Sanders Peirce e dos primeiros estudantes peirceanos de Lógica (Christine Ladd e O. H. Mitchell nos Studies in Logic, 1883) dentro do debate inspirador da visão da linguagem dentro da Filosofia Analítica, conhecido como “Lingua Universalis contra Calculus Ratiocinator”, cujos primórdios podem ser traçados desde a filosofia de Gottfried Leibniz. Para isso, comparamos esse campo do pensamento peirceano com o debate crucial entre a conceitografia de Gottlob Frege (Begriffsschrift, 1879) (...) e a lógica algébrica de George Boole (An investigation of the Laws of Thought on which are founded the mathematical theories of Logic and Probabilities, 1854). O nosso objetivo principal é observar que esse momento da filosofia peirceana pode ser comparado com o pensamento wittgensteiniano, especialmente em sua nova vertente, chamada New Wittgenstein, que tenta superar a tradicional divisão entre Tractatus Logico-Philosophicus e Investigações Filosóficas. Pela comparação entre pensadores influenciados por C. S. Peirce e a filosofia de Ludwig Wittgenstein, pretendemos abrir caminhos na compreensão do conceito de jogo de linguagem, especialmente em sua gramática e em seus operadores simbólicos, através da observação das funções de verdade [truth functions] e as tabelas de verdade [truth tables] enquanto lógica algébrica. (shrink)

Philosophy undergraduate course completion work published in 2015. This work examines Frege's concept of logical law and its relationship to other normative and descriptive approaches in the history of philosophy, as well as epistemological conceptions of the a priori aspects of mathematical knowledge.

Queremos neste ensaio caracterizar de modo introdutório o essencial do legado de Gottlob Frege para a Filosofia da Linguagem contemporânea, identificando e caracterizando os traços distintivos mais genéricos de uma teoria do significado (ou conteúdo semântico) inspirada nas suas ideias seminais e contrastando-a com outras concepções actuais influentes acerca do significado, em especial as posições sobre o conteúdo singular (conteúdo expresso por nomes próprios e outros termos singulares) remotamente inspiradas em ideias de John Stuart Mill.

نگاهی به تفسیر و انتقادات دامت از آموزه‌های فرگه پیرامون مباحث معناشناختی .

Bertrand Russell in his essay On Denoting [1905] presented a theory of description developed in response to the one proposed by Gottlob Frege in his paper Über Sinn und Bedeutung [1892]. The aim of our work will be to show that Russell underestimated Frege three times over in presenting the latter’s work: in relation to the Gray’s Elegy argument, to the Ferdinand argument, and to puzzles discussed by Russell. First, we will discuss two claims of Russell’s which (...) do not do justice to Frege: that we speak of a sense by means of quotation marks, and that all Frege does to cope with phrases that might denote nothing is define an arbitrary object as their reference. Second, we will show that Russell omitted the fact that Frege’s theory provided some answers for the puzzles presented by Russell in his essay. (shrink)

Das letzte halbe Jahrhundert hat einen unvergleichlichen Siegeszug der Molekularbiologie erlebt, zu dem die Genomik, die molekulare Zell- und Entwicklungsbiologie, die Epigenetik sowie Erkenntnisse der Stammzellbiologie als tragende Säulen beigetragen und die Biowissenschaften insgesamt in die sogenannte postgenomische Ära geführt haben. Anstelle eines verengten Blicks in den Kern der Zelle und seiner DNA hat sich das Visier von Biologen auf eine sich dynamisch verändernde Zellumgebung hin geöffnet. Wechselwirkungen zwischen molekularen, zellulären, organismischen bis hin zu ökologischen Hierarchieebenen, stets aufwärts und abwärts (...) interagierend (bottom-up und top-down), bestimmen das Bild postgenomischer Naturbetrachtung. Dieses erweiterte Gesichtsfeld führte einerseits weg von einem strikten Gen-gesteuerten Determinismus hin zu Systemdenken und zur Systembiologie. Zum anderen rückten auf diesem Weg wieder Lücken in der klassischen neodarwinistischen Lehre in den Fokus, die nach einer erweiterten Synthese der Standardlehre der Evolution rufen. So hat das neue Forschungsfeld Evo-Devo (Akronym für Evolutionary Developmental Biology) erstmals molekulare Mechanismen für die sprunghafte Entstehung von Merkmalen aufgezeigt, die die Grundlage für die Entstehung neuer Baupläne (Makroevolution) bildeten. (shrink)

Die Frage nach der Vererbung von Eigenschaften bei Lebewesen beschäftigt den Menschen seit alters her: das ist Genetik. Auch lange schon beschäftigen sich Biologen mit der Frage, wie sich die vielen Tierarten im Laufe einer langen Stammesgeschichte herausbilden konnten: das ist Evolution. Wie wird Konstantes über Generationen bewahrt und Diverses/Neues eingeführt? Die überragenden Erfolge der Genetik haben uns im Glauben eingelullt, wir hätten diese Prozesse vollständig verstanden. Mit dem Aufkommen der so genannten Epigenetik kommen Grundlagen sowohl der Individual-, wie auch (...) der Stammesentwicklung jedoch wieder ins Schwanken. In diesem Artikel will ich einen kleinen Einblick in das Feld der Epigenetik und ihre gesellschaftliche Relevanz geben. (shrink)

Nach neodarwinistischem Verständnis der Evolution entstehen neue Organismen letztlich durch rein zufällige Mutationsprozesse auf genetischer Ebene. Ihre Überlebenschancen werden dann durch die jeweilig herrschende Umwelt begünstigt oder unterdrückt. Die Evolution ist demnach nur vom reinen Zufall geleitet. Neuere Einsichten aus Entwicklungsbiologie (EvoDevo) und Epigenetik haben unsere Sicht der Evolutionsabläufe jedoch deutlich erweitert. Dabei kommt der Umwelt eine lenkende Rolle zu, der reine Zufall verliert an Bedeutung. Damit lässt sich naturwissenschaftliches Verständnis wieder besser mit herkömmlichen Schöpfungsbildern versöhnen.

Molecular developmental biology has expanded our conceptions of gene actions, underpinning that embryonic development is not only governed by a set of specific genes, but as much by space–time conditions of its developing modules. Typically, formation of cellular spheres, their transformation into planar epithelia, followed by tube formations and laminations are modular steps leading to the development of nervous tissues. Thereby, actions of organising centres, morphogenetic movements, inductive events between epithelia, tissue polarity reversal, widening of epithelia, and all these occurring (...) orderly in space and time, are driving forces of emergent laminar neural tissues, e.g. the vertebrate retina. Analyses of self-organisational formation of retina-like 3D structures from dispersed cells under defined cell culture conditions demonstrate that not only particular genetic networks, but—at least as important—the applied culture conditions define phenotypes of emergent tissues. Such in vitro approaches allow assigning emerging tissue formation to ground-laying genetic networks separately from contributions by conditional constraints. (shrink)

Berge von brennenden Tieren, Bilder vom „Keulen“, Bilder vom geklonten Menschen. Aber auch Euphorisches: nach der Aufklärung des menschlichen Genoms schöpfen Krebs- und AIDS-Kranke, Querschnittsgelähmte und Alzheimer-Patienten neue Hoffnung. Bilder auch von Börsenkursen: vom neuen Markt der Informations- und Biotechnologien hängt unsere ökonomische Zukunft ab. Hinter allem stecken die „Life Sciences“, und oft wird man mit schrägem Blick gefragt, was das für Leute sind, diese Bio- bzw. Lebenswissenschaftler? Die Frage nach den Möglichkeiten und dem wahren Wert des biomedizinischen Fortschritts, nach (...) seiner Kontrolle, nach seiner Verantwortung, nach seiner gesellschaftlichen Bindung wird lauter. (shrink)

Bei der Suche nach dem rätselhaften Ursprung des Phänomens „Leben“ wird hier zunächst die zelluläre Ebene betrachtet. Im Grundaufbau zeigen alle Zellen viel Konstantes, aber gleichzeitig stellt jede Zelle ein einmaliges Individuum dar. Leben von Zellen gibt es nur als gegenseitiges Wechselspiel mit ihrer jeweiligen Umwelt. Das Genom (die Gesamtheit aller Gene) bleibt ab der Befruchtung in jeder Zelle eines Individuums konstant. Aber auch die Verwirklichung der Gene braucht eine „molekulare Umwelt“, besonders die vom Muttertier vorbereitete Umwelt im Zytoplasma des (...) Eies. Individualität eines Organismus (z.B. des Menschen) wird also nicht allein vom Genom festgelegt, sondern ist durch Entwicklungsprozesse bedingt (braucht Zeit!). „Leben“ kann (muß?) somit begriffen werden als ein wechselseitiges Kontinuum, welches alle Individuen, alle Spezies und alle Generationen miteinander und ihren Umwelten verbindet. Wie phylogenetisch betrachtet die allererste Zelle aus abiotischen Umständen entstehen konnte, wird hier nicht behandelt. Das Gesagte legt allerdings nahe, dass es nicht Gene waren, die sich eine belebte Welt erschufen, sondern bestimmte (Um-)Welten „erschufen“ sich Gene, die „lebenstauglich“ waren. (shrink)

Seit der Aufklärung versucht der Mensch, Gott abzuschaffen. Dabei fällt der Zufälligkeit, und damit auch der Ziellosigkeit in der darwinistischen Sicht der Evolution besonderes Gewicht zu. Diese weithin akzeptierten Dogmen stehen diametral gegen jahrtausendealte Vorstellungen, die letztlich in allen Kulturen und Religionen hervorgebracht wurden, daß die Natur eine Schöpfung Gottes sei, in der der Mensch das höchste, Gott-ebenbildliche Wesen sei. Nach Erkenntnissen der klassischen Genetik schienen Gene an die Stelle von Gott getreten zu sein: sie haben absolute Gewalt und beherrschen (...) die belebte Natur. Sie haben je einen eindeutigen Befehl, sind unbeugsam und gerecht, wie Gott im AT. Das Produkt Mensch ist nur einer ihrer zahllosen Spielbälle, existiert vorübergehend, ein Zigeuner in einer verlassenen Ecke des Kosmos (Monod, 1992). Diese neodarwinistische Sicht, die nicht zuletzt zum Niedergang der Kirchen bei uns beiträgt, wird von neuen Erkenntnissen der Entwicklungsbiologie (EvoDevo) infrage gestellt. (shrink)

Anlaß zum vorliegenden Artikel gab eine Tagung zum Thema „Gott-Geist-Gehirn“, bei der im Dialog zwischen Theologen und Neurowissenschaftlern Beziehungen zwischen diesen drei Begriffen diskutiert wurden. Aus biologischer Sicht sind es vor allem Hirnleistungen, welche uns spezifisch zum Menschen machen. Die Entstehung der Hirnstrukturen während der Embryonal- und Postnatalperiode wird im ersten Teil behandelt, deren Verständnis essentiell ist. Im zweiten Teil werden physiologische Fähigkeiten des menschlichen Gehirns am Beispiel des visuellen Systems in sehr verkürzter Weise dargestellt, um zu untersuchen, inwieweit physiologische (...) Erkenntnisse das Phänomen der Wahrnehmung bis hin zur Entstehung von Bewusstsein erklären können. Weil sich hier Verständnislücken auftun, die nach meinem Dafürhalten grundsätzlich und unlösbar sind (Qualia-Problem), komme ich schließlich zur Unvollständigkeit jeglicher naturwissenschaftlichen Weltsicht (unendliche Regresse) und die damit notwendige Annahme einer „Ur-Ursache“ dieser Welt, wie sie schon von Aristoteles im kosmologischen Gottesbeweis formuliert wurde. So führt diese Betrachtung zum Schluß, dass insbesondere Naturwissenschaftler einer Ur-Ursache bedürften (Gottesbedürftigkeit). (shrink)

Physiologie und Struktur komplexer Gehirne lassen sich durch Betrachtung evolutions- und entwicklungsbiologischer Abläufe analysieren, was der Hirnforschung tiefe Einblicke bis zur molekularen Ebene erlaubt. In knappster Form werden grundlegende Aspekte der Stammes- und Individualentwicklung (Phylo- und Ontogenese) von Gehirnen im Tierreich beschrieben, bis hin zum menschlichen Gehirn, dessen Grobgliederung skizziert wird. Das Lernvermögen insbesondere von Kleinkindern ist aufgrund postnataler Hirnplastizität erklärbar. Systematische Unterschiede zwischen einzelnen Zellen und Neuronenverbänden sind für selbstorganisierende Bewußtseinsprozesse bedeutsam. Am Beispiel der stufenweisen visuellen Signalverarbeitung wird die (...) mögliche Wahrnehmung von Bildern diskutiert, um danach gängige Theorien zur Bewußtseinsfrage einander gegenüber zu stellen. Schließlich wird auf das Qualia-Problem eingegangen, was vom Autor als Unerklärbarkeit des Bewußtseinsinhalts und als Urfrage des Leib-Seele-Problems verstanden wird. Sie kann wohl auch durch modernste biologische Forschung nicht beantwortet werden. (shrink)

Darwin´s Erkenntnis über die Abstammung der Arten durch Mutation und Selektion sind in aller Munde, dass aber darüber im Detail noch viel Unklarheit herrscht, ist weniger bekannt. Es sind Fortschritte der Entwicklungsbiologie, die erst seit wenigen Jahren uns molekulare Erklärungsmuster an die Hand geben, mit denen die Entstehung neuer Arten besser verständlich wird. Es handelt sich um die Aufklärung der Wirkungsweise von Genen und ihren molekularen Produkten, die während der embryonalen Entwicklung von Tier und Mensch dafür sorgen, daß der Organismus (...) sich normal entwickelt. Treten Veränderungen (Mutationen) in einem dieser Mastergene auf, so wird dies zur Missbildung oder gar zum Absterben des betreffenden Embryos führen. Aber in seltenen Fällen kann so auch eine neue Tierart begründet werden. Gerade im Darwin-Jahr werden die Lehrbücher zur Evolutionsbiologie um ein wesentliches Kapitel erweitert. Es ist mit EvoDevo überschrieben und will damit ausdrücken, daß Evolutionary Theory ohne Developmental Biology keinen Sinn macht. Die bisherigen Lücken im Verständnis des Evolutionsgeschehens und die neue Sicht von EvoDevo wird im Folgenden dargestellt werden. (shrink)

This dissertation is about the structure of thought. Following Gottlob Frege, I define a thought as the sort of content relevant to determining whether an assertion is true or false. The historical component of the dissertation involves interpreting Frege’s actual views on the structure of thought. I argue that Frege did not think that a thought has a unique decomposition into its component senses, but rather the same thought can be decomposed into senses in a variety (...) of distinct ways. I extend Frege’s position and use it to develop an account of the hierarchy of senses, the senses expressed by indexicals and demonstratives, and the distinction between logical and non-logical structure. I also discuss various connections with the nature of meta-representation, our capacity for reflective judgment, some aspects of the structure of conscious experience, the way we perceive regions of space and durations of time, and our conscious awareness of our own perceptions and events of thinking. (shrink)

Analytic philosophy has been perhaps the most successful philosophical movement of the twentieth century. While there is no one doctrine that defines it, one of the most salient features of analytic philosophy is its reliance on contemporary logic, the logic that had its origin in the works of George Boole and Gottlob Frege and others in the mid‐to‐late nineteenth century. Boolean algebra, the heart of Boole's contributions to logic, has also come to represent a cornerstone of modern computing. (...) Frege had broad philosophical interests, and his writings on the nature of logical form, meaning and truth remain the subject of intense theoretical discussion, especially in the analytic tradition. Frege's works, and the powerful new logical calculi developed at the end of the nineteenth century, influenced many of its most seminal figures, such as Bertrand Russell, Ludwig Wittgenstein and Rudolf Carnap. (shrink)

Never was dogmatic reductionism helpful in conceiving the phenomenon of life. The post-genomic era has made it clear that genes alone cannot explain the functioning of whole organisms. Already each cell represents a unique, non-recurring individual. Recent progress in developmental biology has conveyed new perspectives both on the makings of individual organisms (ontogeny), as on evolutionary change (Evo-Devo). The genome (the entirety of all genes) of an animal remains constant from fertilization onwards in each cell. The realization of genes requires (...) molecular environments, in particular pertinent to the cytoplasm of the unfertilized egg. Individuality of an organism therefore is not only determined by its genome, but is shaped through developmental processes (it needs time!). Organisms can only exist through mutual interplays with their respective (molecular and cellular) environments at all levels of organization. Thus, life can be conceived of as endless networks of communication, e.g. as a mutual continuum, connecting all individuals, all species and all generations within their given environments. Evolutionarily, nature does not select fitting genes, but rather viable traits. The presented concepts render it unlikely that it was genes that founded our living world, but rather that distinct environments shaped “genes” (of whatever chemical nature) which proved to be “life-suitable”. (shrink)