Kay Herrmann

Jakob Friedrich Fries (1773–1843) zählt sicherlich zu den bedeutendsten Denkern der auf Kant folgenden Phase der deutschen Philosophie. Das wird in eindrucksvoller Weise durch die Beiträge dieses Bandes belegt, die aus Vorträgen auf dem Fries-Symposion hervorgingen, das im Oktober 1997 an der Friedrich-Schiller-Universität Jena stattfand. Die Autoren beleuchten die Lebensumstände von Fries, ordnen sein Werk philosophiegeschichtlich ein und setzen sich systematisch mit erkenntnistheoretischen, naturphilosophischen, wissenschaftstheoretischen und politischen Aspekten seiner Philosophie auseinander. Auch die Rezeption des Fries’schen Werkes bei Naturwissenschaftlern wie M. J. Schleiden und Philosophen wie E. F. Fries und L. Nelson kommt zur Sprache.

Nelson's Proof of the Impossibility of the Theory of Knowledge -/- In addressing the possibility of a theory of knowledge, Leonard Nelson noted the contradiction of an epistemological criterion that one would require in order to differentiate between valid and invalid knowledge. Nelson concluded that the inconsistency of such a criterion proves the impossibility of the theory of knowledge. -/- Had the epistemological criterion had a perception, then it would presume to adjudicate on its own truth (thus epistemological circular argument). However, if one were to assume that the criterion is not knowledge, one would then have to justify how this is a criterion for truth - yet this would only be possible when it may be considered as an object of knowledge. One would equally have had to predetermine the criterion in order to determine the truth of this knowledge, thereby providing another circular argument. Ostensibly, every criterion of truth fails at its very own test since it cannot guarantee its own truth, just as Munchausen, contrary to his assertion, could not draw himself out of the swamp by tugging on a tuft of his own hair. -/- Nelson proposed a solution of the epistemological problem (the question of the differentiation between valid and invalid knowledge), that based on Jakob Friedrich Fries' differentiation between proof and deduction. Proof, according to Nelson (in reference to Fries), can be defined as derivation of truth from one statement from another statement. Thus, from the truth in the statement that "all men are mortal", one is then able to say that "Socrates is a man" and thence extrapolate from the truth of the statement that "Socrates is mortal." If knowledge were to be considered somewhat judgmental (in a statement), then an attempt at proof (i.e. recourse to previous judgments) would inevitably lead to an infinite regression in justification, since each judgment would necessitate a further justification from another judgment. Every attempt to prove an epistemological criterion is thus also confronted by this regression in justification. -/- Nelson's attempt at a solution rests on the assumption of the existence of an immediate knowledge as a justification of the truth (mediate) of knowledge. Nelson considers immediate knowledge to be non-judgmental knowledge. These include intuitions (e. g. seeing-the-red-roof) and also philosophical knowledge that pre-exists in his opinion before a judgmental reflexion (immediate) in our reason (e. g. the principle of causality). -/- Proof of the truth of mediate knowledge can be effected by showing its compliance with attendant immediate knowledge (rational truth = correspondence of mediate knowledge with their immediate knowledge). Nelson considered this as a resolution of the circular epistemological argument. In regard to philosophical knowledge, Nelson sees these as subject to deduction and not proof. The following example illustrates the goal of deduction: -/- An approach for deducing the principle of causality: A) Every change has a cause. (The principle of causality) A´) A is a reiteration of an immediate knowledge. (Meta-assertion following A) -/- "A" may not be provable, but A´ may justified, and thus Nelson identified it as a deduction following from A. // reference: http://www.friesian.com/nelproof.htm

Sofern man die Existenz objektiver Erkenntnisse anerkennt, ist man mit der Frage nach den Bedingungen der Möglichkeit für diese Erkenntnisse konfrontiert. Der Grund muss in Voraussetzungen liegen, die selbst wiederum empirisch nicht zu rechtfertigen sind. Zwar verwerfen Popper und Carnap den Begriff des "synthetischen Urteils a priori", doch die Voraussetzung, dass es "in der Natur gesetzlich zugeht", räumen beide ein. Diese empirisch nicht zu rechtfertigende Prämisse ist ein synthetisches Urteil a priori. Gemäß Kant ist innerhalb der Klasse der Erkenntnisse a priori zwischen reinen und nicht-reinen Erkenntnissen a priori zu unterscheiden. Es in vorliegender Arbeit argumentativ dafür plädiert, Naturgesetze als apriorische Erkenntnisse zu betrachten, die der Klasse der nicht-reinen synthetischen Urteile a priori zuzurechnen sind. Vor diesem Hintergrund kommt die Arbeit zu der Schlussthese: Ein empirischer (d. h. empirische Begriffe enthaltender) Satz (etwa ein Naturgesetz) kann über den (empirisch nicht einlösbaren, aber als Postulat durchaus sinnvollen) Anspruch auf allgemeine und notwendige Geltung verfügen und somit Bedingungen der Möglichkeit für objektive Erkenntnis formulieren. Doch sind für die Entdeckung empirischer Sätze mit Anspruch auf allgemeine und notwendige Geltung empirische Studien (etwa das physikalische Experiment) erforderlich.

Stephen Hawking claims: Philosophy is dead! Natural scientists use terms like 'natural law', 'matter', 'nature' and 'theories'. Often these terms are taken for granted without reflection. The task of philosophy of science as a metatheory of science is to clarify these terms. In doing so, philosophy of science is confronted with epistemological, ontological and metaphysical questions. But it also deals with questions such as "How do we define the boundaries between different scientific disciplines?" or "How do we distinguish science from pseudoscience?". In addition, philosophy of science deals with ethical problems of modern technology, with methodological issues, with reconstructing the structure and development of scientific theories, and with exposing ideological paternalism of science. The optimistic conclusion is: Philosophy is not dead - but philosophers must discuss with scientists on an equal footing.

According to the scientific ideal of modernity, the propositions of science are considered fundamentally fallible. On the other hand, science strives for objective knowledge. Kant saw in the apriori the precondition for objective knowledge. But with the new conception of science the apriori (if it is not to be only logic) has become problematic. With it, however, the objectivity of scientific knowledge is at stake. As long as one grants objectivity to scientific knowledge, the question of the apriori remains topical. On the one hand, this volume wants to trace the historical roots as well as the different interpretations of the apriori, and on the other hand, it wants to ask for approaches for a contemporary reinterpretation of this basic concept.

The question of time travel stimulates the imagination and provides material for whimsical stories. A work on the topic of "time travel" forces us to deal with the concept of "time". The complexity and the antinomic character of this concept make it difficult to grasp "time" more precisely. We encounter time as a form of perception in its deeply subjective aspect, as a biological rhythm, as a social phenomenon in the sense of a collective determination of time, but also as a physical quantity. Einstein's theory of relativity revolutionized our ideas of space and time. His Special Theory of Relativity (1905) allows "travel into the future" through the effect of time dilation he predicted, and Einstein's theory of gravity allows for closed time lines as solutions to its equations (e.g., Gödel cosmos, anti-de Sitter cosmos). However, traveling in a time loop would immediately lead to a number of paradoxes (e.g., grandfather paradox, information paradox). Although, surprisingly, the basic laws of physics (apart from extremely rare and macroscopically non-appearing quantum mechanical effects) would not be violated in a time reversal, there seems to be a fundamental prohibition of traveling into the past in nature.

Metaphysics as the foundation of science, philosophy as an exact method to discover this foundation: These are central themes in the Kant-Friesian philosophy which, at the beginning of the 20th century, Leonard Nelson, using the methods of mathematical axiomatics, further developed into interdisciplinary research programmes. Nelson carried out this research programme in his ethics but his untimely death prevented a systematic presentation of his natural philosophy and his doctrine of method. The present volume contains four transcripts of his seminars on natural philosophy which he held over a period of 15 years. The transcripts, which may be taken as a comparatively complete presentation of Nelson's natural philosophy, supplement the writings published during his lifetime and convey a representative picture of his natural philosophy. // Metaphysik als Fundament der Wissenschaften, Philosophie, eine exakte Disziplin, die dieses Fundament offenlegt: Leitmotive des Kant-Fries’schen Denkgebäudes, die Leonard Nelson zu Beginn des 20. Jahrhunderts in interdisziplinäre Forschungsprogramme umsetzt. Die dabei angewandten – an der mathematischen Axiomatik ausgerichteten – Methoden haben nichts an Aktualität eingebüßt. Kann Nelson dieses Vorhaben bezüglich seiner Ethik verwirklichen, so verhindert sein früher Tod eine systematische Darstellung seiner Naturphilosophie und Methodenlehre. Der vorliegende Band enthält vier Mitschriften von Lehrveranstaltungen Nelsons. Diese Schriften, die die zu seinen Lebzeiten veröffentlichten Arbeiten zur Naturphilosophie ergänzen und erweitern sollen, decken einen Zeitraum von ca. 15 Jahren ab und geben somit einen repräsentativen Einblick in Nelsons naturphilosophisches Schaffen. Die vorliegende Zusammenstellung naturphilosophischer Nachlassschriften darf als verhältnismäßig vollständig gelten.

Naturwissenschaften, Mathematik und Logik waren für Nelson von zentraler Bedeutung. Er pflegte bereits als Jugendlicher intensive Kontakte zu Naturwissenschaftlern und Mathematikern. Dadurch erhielt er Anregungen, die von Anfang an seine philosophischen Ansätze beeinflussten. Inspiriert von der Kant-Fries’schen Philosophie und der Axiomatik der Mathematik, konzipierte Nelson seine Philosophie als exakte Wissenschaft. Wie Kant und Fries betrachtete Nelson die Suche nach den allgemeinen Prinzipien der Naturwissenschaften als Hauptaufgabe der Naturphilosophie. Ergebnis dieser kritischen Analyse ist ein System von metaphysischen Grundsätzen der Naturwissenschaft. Nelson übernimmt Kants Lehre von den Grundsätzen des reinen Verstandes. Keine empirisch gefundene Gesetzmäßigkeit könne diesen Grundsätzen widersprechen. Für die Gesetze der Newton’schen Mechanik hätten, so meint Nelson, Kant und Fries diesen Nachweis erbracht. Deshalb formulierte Nelson das sogenannte Postulat der Mechanistik, gemäß dem alle Naturerscheinungen auf mechanische Vorgänge zurückgeführt werden können. Das starre Festhalten an diesem Postulat veranlasste ihn zur Ablehnung bedeutsamer physikalischer Konzeptionen (z. B. des auf der Elektrodynamik basierenden Relativitätsprinzips, des Nahwirkungskonzepts und des Atommodells). Das „Relativitätsprinzip der Elektrodynamik“ lehnte er mit dem Argument ab, es verhindere die Anwendung der dritten Analogie der Erfahrung, da es den Verzicht auf den Begriff der Gleichzeitigkeit von Naturerscheinungen erzwinge. Eine kritische Nelson-Rezeption muss der Historizität etlicher Thesen Nelsons Rechnung tragen, aber zugleich die Bedeutsamkeit von Kernaussagen Nelson’scher Naturphilosophie im Hinblick auf die modernen Naturwissenschaften untersuchen. Das ist auch die Zielrichtung des vorliegenden Beitrages. Der erste Teil beleuchtet Nelsons wissenschaftliches Umfeld. Einerseits wird untersucht, welche Wissenschaftler Nelson beeinflussten, andererseits soll dargestellt werden, welcher Personenkreis an der Fortentwicklung der Nelson’schen Naturphilosophie beteiligt war. Beispielhaft sollen daran anschließend zwei Themenbereiche aus seinem reichhaltigen Werk disktiert werden, denen besonders im Hinblick auf aktuelle philosophische Diskussionsschwerpunkte Bedeutsamkeit zukommt. Im zweiten Teil werden nämlich Nelsons Betrachtungen zum Verhältnis von Freiheit und Naturnotwendigkeit sowie seine Unterscheidung zwischen wissenschaftlicher und ästhetischer Naturbetrachtung besprochen. Der Beitrag beansprucht nicht, die Rezeptionssgeschichte und den Inhalt von Nelsons Naturphilosophie sowie die aktuelle Bedeutsamkeit seiner Thesen im Detail darzustellen aufzuarbeiten. Vielmehr geht es darum, Ansätze für eine zeitgemäße Interpretation Rezeption aufzuzeigen und anhand von Beispielen zu erörtern.

The problem of synthetic judgments touches upon the question whether philosophy is in fact capable of making independent truth statements. According to Kant, synthetic judgments formulate the conditions for the possibility of objectively valid knowledge a priori. As far as empirical attempts at reinterpretation of the aprioristic fall short of this ambition, Kant’s a priori goes deeper. This is because modern science strives towards objective knowledge, although its statements are fundamentally fallible. The topic of synthetic a priori thus continues to be relevant. -/- This paper will show that, in order to be viable at all, a modernized version of transcendental philosophy must ‘depart from’ the concepts of “independence from empirics” and/or the “purity” of the aprioristic. Kant’s reflections on non-pure synthetic a priori knowledge already contain attempts at this. Furthermore, the aprioristic validity of knowledge does not exclude the possibility, that it can be discovered empirically. Fries and, subsequently, Nelson proceeded with this separation (initially ascribed to Reichenbach) between the contexts of validity and discovery of knowledge, pointing out that the a priori can indeed be discovered empirically, yet never be proven. -/- Currently, there are still a number of valid reasons for arguing that concepts from transcendental philosophy continue to be of fundamental importance for the modern sciences. However, it must not be neglected that, even within a modernized framework of transcendental philosophy various unsolved problems remain and/or are created (such as the unfeasibility of the aprioristic claim to general validity and necessity, the problem of drawing a clear boundary between the noumenal and phenomenal worlds). Moreover, the “beautiful structure” of the Kantian system, which constitutes much of its persuasive strength, is lost.

Das Problem einer einheitlichen Grundlage alles Bestehenden hat seit jeher eine große Rolle in der Philosophie gespielt und stets auch eine große Ausstrahlung auf die Naturwissenschaft gehabt. Exemplarisch werden verschiedene Entwürfe für eine höherdimensionale einheitliche Feldtheorie diskutiert. -/- Es wird der Frage nachgegangen, was überhaupt unter der „Einheit von Theorien“ zu verstehen ist. Dabei zeigt sich, dass sich zwischen unterschiedlichen Ebenen der „Einheit von Theorien“ unterscheiden lässt. Die „Einheit von Theorien“ kann sich beziehen auf übergreifende Begriffe (z. B. Feldbegriff), auf eine formal mathematische Zusammenfassung unterschied­licher Phänomene (z. B. im Rahmen der Projektiven Einheitlichen Feldtheorie), auf einen genetischen Zusammenhang von Theorien (z. B. zwischen newtonscher und relativistischer Mechanik), auf ein einheitliches Gesetz zur Erklärung unterschiedlicher Phänomene (z. B. die Maxwelltheorie als Erklärungsgrundlage elektromagnetischer Erscheinungen), aber auch auf einen gemeinsamen Referenzbereich verschiedener Theorien (z. B. phänomenologische und statistische Thermodynamik). -/- Die Verwendung höherdimensionaler Geometrien wirft die Frage nach dem ontologischen Status höherdimensionaler Raum-Zeiten auf. Handelt es sich lediglich um mathematische Formalismen, oder kommt ihnen eine eigene Realität zu? Es zeigt sich, dass beide Interpretationskonzepte ihre Berechtigung besitzen. Spielt etwa bei der Klasse der Projektiven Einheitlichen Feldtheorien (kurz: PUFT) der höherdimensionale Raum die Rolle eines Instruments zur mathematisch eleganten Darstellung, so lassen sich bei der Klasse der Kaluza-Klein-Theorien Eigenschaften ableiten, die als Hinweis auf einen ontologisch eigenständigen Realitätsstatus gedeutet werden können. Folgt man Poppers Realitätskriterium, wonach als real zu betrachten ist, was sich durch physikalische Wirkungen nachweisen lässt, so kann etwa der Einfluss der Extradimensionen auf die Dynamik des physikalischen Geschehens in der vierdimensionalen Raum-Zeit als Hinweis auf deren Realität gedeutet werden. -/- Interessant sind die höherdimensionalen einheitlichen Feldtheorien auch unter dem Blickwinkel der Wissenschaftstheorie. Da sie recht gut dem Modell des Forschungsprogramms im Sinne von Lakatos entsprechen, stellen sie gute Musterbeispiele für theoriedynamische Betrachtungen dar.

Jakob Friedrich Fries (1773-1843): A Philosophy of the Exact Sciences -/- Shortened version of the article of the same name in: Tabula Rasa. Jenenser magazine for critical thinking. 6th of November 1994 edition -/- 1. Biography -/- Jakob Friedrich Fries was born on the 23rd of August, 1773 in Barby on the Elbe. Because Fries' father had little time, on account of his journeying, he gave up both his sons, of whom Jakob Friedrich was the elder, to the Herrnhut Teaching Institution in Niesky in 1778. Fries attended the theological seminar in Niesky in autumn 1792, which lasted for three years. There he (secretly) began to study Kant. The reading of Kant's works led Fries, for the first time, to a deep philosophical satisfaction. His enthusiasm for Kant is to be understood against the background that a considerable measure of Kant's philosophy is based on a firm foundation of what happens in an analogous and similar manner in mathematics. -/- During this period he also read Heinrich Jacobi's novels, as well as works of the awakening classic German literature; in particular Friedrich Schiller's works. In 1795, Fries arrived at Leipzig University to study law. During his time in Leipzig he became acquainted with Fichte's philosophy. In autumn of the same year he moved to Jena to hear Fichte at first hand, but was soon disappointed. -/- During his first sojourn in Jenaer (1796), Fries got to know the chemist A. N. Scherer who was very influenced by the work of the chemist A. L. Lavoisier. Fries discovered, at Scherer's suggestion, the law of stoichiometric composition. Because he felt that his work still need some time before completion, he withdrew as a private tutor to Zofingen (in Switzerland). There Fries worked on his main critical work, and studied Newton's "Philosophiae naturalis principia mathematica". He remained a lifelong admirer of Newton, whom he praised as a perfectionist of astronomy. Fries saw the final aim of his mathematical natural philosophy in the union of Newton's Principia with Kant's philosophy. -/- With the aim of qualifying as a lecturer, he returned to Jena in 1800. Now Fries was known from his independent writings, such as "Reinhold, Fichte and Schelling" (1st edition in 1803), and "Systems of Philosophy as an Evident Science" (1804). The relationship between G. W. F. Hegel and Fries did not develop favourably. Hegel speaks of "the leader of the superficial army", and at other places he expresses: "he is an extremely narrow-minded bragger". On the other hand, Fries also has an unfavourable take on Hegel. He writes of the "Redundancy of the Hegelistic dialectic" (1828). In his History of Philosophy (1837/40) he writes of Hegel, amongst other things: "Your way of philosophising seems just to give expression to nonsense in the shortest possible way". In this work, Fries appears to argue with Hegel in an objective manner, and expresses a positive attitude to his work. -/- In 1805, Fries was appointed professor for philosophy in Heidelberg. In his time spent in Heidelberg, he married Caroline Erdmann. He also sealed his friendships with W. M. L. de Wette and F. H. Jacobi. Jacobi was amongst the contemporaries who most impressed Fries during this period. In Heidelberg, Fries wrote, amongst other things, his three-volume main work New Critique of Reason (1807). -/- In 1816 Fries returned to Jena. When in 1817 the Wartburg festival took place, Fries was among the guests, and made a small speech. 1819 was the so-called "Great Year" for Fries: His wife Caroline died, and Karl Sand, a member of a student fraternity, and one of Fries' former students stabbed the author August von Kotzebue to death. Fries was punished with a philosophy teaching ban but still received a professorship for physics and mathematics. Only after a period of years, and under restrictions, he was again allowed to read philosophy. From now on, Fries was excluded from political influence. The rest of his life he devoted himself once again to philosophical and natural studies. During this period, he wrote "Mathematical Natural Philosophy" (1822) and the "History of Philosophy" (1837/40). -/- Fries suffered from a stroke on New Year's Day 1843, and a second stroke, on the 10th of August 1843 ended his life. -/- 2. Fries' Work Fries left an extensive body of work. A look at the subject areas he worked on makes us aware of the universality of his thinking. Amongst these subjects are: Psychic anthropology, psychology, pure philosophy, logic, metaphysics, ethics, politics, religious philosophy, aesthetics, natural philosophy, mathematics, physics and medical subjects, to which, e.g., the text "Regarding the optical centre in the eye together with general remarks about the theory of seeing" (1839) bear witness. With popular philosophical writings like the novel "Julius and Evagoras" (1822), or the arabesque "Longing, and a Trip to the Middle of Nowhere" (1820), he tried to make his philosophy accessible to a broader public. Anthropological considerations are shown in the methodical basis of his philosophy, and to this end, he provides the following didactic instruction for the study of his work: "If somebody wishes to study philosophy on the basis of this guide, I would recommend that after studying natural philosophy, a strict study of logic should follow in order to peruse metaphysics and its applied teachings more rapidly, followed by a strict study of criticism, followed once again by a return to an even closer study of metaphysics and its applied teachings." -/- 3. Continuation of Fries' work through the Friesian School -/- Fries' ideas found general acceptance amongst scientists and mathematicians. A large part of the followers of the "Fries School of Thought" had a scientific or mathematical background. Amongst them were biologist Matthias Jakob Schleiden, mathematics and science specialist philosopher Ernst Friedrich Apelt, the zoologist Oscar Schmidt, and the mathematician Oscar Xavier Schlömilch. Between the years 1847 and 1849, the treatises of the "Fries School of Thought", with which the publishers aimed to pursue philosophy according to the model of the natural sciences appeared. In the Kant-Fries philosophy, they saw the realisation of this ideal. The history of the "New Fries School of Thought" began in 1903. It was in this year that the philosopher Leonard Nelson gathered together a small discussion circle in Goettingen. Amongst the founding members of this circle were: A. Rüstow, C. Brinkmann and H. Goesch. In 1904 L. Nelson, A. Rüstow, H. Goesch and the student W. Mecklenburg travelled to Thuringia to find the missing Fries writings. In the same year, G. Hessenberg, K. Kaiser and Nelson published the first pamphlet from their first volume of the "Treatises of the Fries School of Thought, New Edition". -/- The school set out with the aim of searching for the missing Fries' texts, and re-publishing them with a view to re-opening discussion of Fries' brand of philosophy. The members of the circle met regularly for discussions. Additionally, larger conferences took place, mostly during the holidays. Featuring as speakers were: Otto Apelt, Otto Berg, Paul Bernays, G. Fraenkel, K. Grelling, G. Hessenberg, A. Kronfeld, O. Meyerhof, L. Nelson and R. Otto. On the 1st of March 1913, the Jakob-Friedrich-Fries society was founded. Whilst the Fries' school of thought dealt in continuum with the advancement of the Kant-Fries philosophy, the members of the Jakob-Friedrich-Fries society's main task was the dissemination of the Fries' school publications. In May/June, 1914, the organisations took part in their last common conference before the gulf created by the outbreak of the First World War. Several members died during the war. Others returned disabled. The next conference took place in 1919. A second conference followed in 1921. Nevertheless, such intensive work as had been undertaken between 1903 and 1914 was no longer possible. -/- Leonard Nelson died in October 1927. In the 1930's, the 6th and final volume of "Treatises of the Fries School of Thought, New Edition" was published. Franz Oppenheimer, Otto Meyerhof, Minna Specht and Grete Hermann were involved in their publication. -/- 4. About Mathematical Natural Philosophy -/- In 1822, Fries' "Mathematical Natural Philosophy" appeared. Fries rejects the speculative natural philosophy of his time - above all Schelling's natural philosophy. A natural study, founded on speculative philosophy, ceases with its collection, arrangement and order of well-known facts. Only a mathematical natural philosophy can deliver the necessary explanatory reasoning. The basic dictum of his mathematical natural philosophy is: "All natural theories must be definable using purely mathematically determinable reasons of explanation." Fries is of the opinion that science can attain completeness only by the subordination of the empirical facts to the metaphysical categories and mathematical laws. -/- The crux of Fries' natural philosophy is the thought that mathematics must be made fertile for use by the natural sciences. However, pure mathematics displays solely empty abstraction. To be able to apply them to the sensory world, an intermediatory connection is required. Mathematics must be connected to metaphysics. The pure mechanics, consisting of three parts are these: a) A study of geometrical movement, which considers solely the direction of the movement, b) A study of kinematics, which considers velocity in Addition, c) A study of dynamic movement, which also incorporates mass and power, as well as direction and velocity. -/- Of great interest is Fries' natural philosophy in view of its methodology, particularly with regard to the doctrine "leading maxims". Fries calls these "leading maxims" "heuristic", "because they are principal rules for scientific invention". -/- Fries' philosophy found great recognition with Carl Friedrich Gauss, amongst others. Fries asked for Gauss's opinion on his work "An Attempt at a Criticism based on the Principles of the Probability Calculus" (1842). Gauss also provided his opinions on "Mathematical Natural Philosophy" (1822) and on Fries' "History of Philosophy". Gauss acknowledged Fries' philosophy and wrote in a letter to Fries: "I have always had a great predilection for philosophical speculation, and now I am all the more happy to have a reliable teacher in you in the study of the destinies of science, from the most ancient up to the latest times, as I have not always found the desired satisfaction in my own reading of the writings of some of the philosophers. In particular, the writings of several famous (maybe better, so-called famous) philosophers who have appeared since Kant have reminded me of the sieve of a goat-milker, or to use a modern image instead of an old-fashioned one, of Münchhausen's plait, with which he pulled himself from out of the water. These amateurs would not dare make such a confession before their Masters; it would not happen were they were to consider the case upon its merits. I have often regretted not living in your locality, so as to be able to glean much pleasurable entertainment from philosophical verbal discourse." -/- The starting point of the new adoption of Fries was Nelson's article "The critical method and the relation of psychology to philosophy" (1904). Nelson dedicates special attention to Fries' re-interpretation of Kant's deduction concept. Fries awards Kant's criticism the rationale of anthropological idiom, in that he is guided by the idea that one can examine in a psychological way which knowledge we have "a priori", and how this is created, so that we can therefore recognise our own knowledge "a priori" in an empirical way. Fries understands deduction to mean an "awareness residing darkly in us is, and only open to basic metaphysical principles through conscious reflection.". -/- Nelson has pointed to an analogy between Fries' deduction and modern metamathematics. In the same manner, as with the anthropological deduction of the content of the critical investigation into the metaphysical object show, the content of mathematics become, in David Hilbert's view, the object of metamathematics. -/-