Leonard Nelson
Leonard Nelson (; ; 11 July 1882 – 29 October 1927), sometimes spelt Leonhard, was a German mathematician, critical philosopher, and socialist. He was part of the neo-Friesian school (named after post-Kantian philosopher Jakob Friedrich Fries) of neo-Kantianism and a friend of the mathematician David Hilbert. He devised the Grelling–Nelson paradox in 1908 and the related idea of autological words with Kurt Grelling. Neo-Friesian subsequently became an influencer in fields of both philosophy and mathematics, as Nelson's close contacts with scientists and mathematicians influenced their ideas. Despite dying earlier than many of his friends and  assistants, his ISK organization lived on after his death, even after being banned by the Nazi Regime in 1933. It is even claimed that Albert Einstein supported it. He's also credited with popularizing the Socratic method in his book "Die sokratische Methode" ("The Socratic Method"). Life. Early life and education. In Nelson's early years, he studied in Französisches Gymnasium Berlin where mathematics and science weren't notable in that school. He was therefore privately tutored by mathematician Gerhard Hessenberg (1874–1925), and began reading the works of philosophers Immanuel Kant, Jakob Friedrich Fries, and Ernst Friedrich Apelts, which began  to spark his interest in philosophy. In 1901, Nelson studied mathematics and philosophy in Heidelberg University for a short period of time, before going to the Humboldt University of Berlin from March 1901 – 1903. From 1903 to 1904, he worked with mathematicians and philosophers in the University of Göttingen, such as; his doctoral advisor Julius Baumann, David Hilbert, Felix Klein, Carl Runge, and his later rival Edmund Husserl. Critical philosophy. Nelson's work as a philosopher was most concerned with critical philosophy, attributed to Kant. It sets out to find a "critique" on science and metaphysics, similar to empiricism, as  things can only be true based on the perceptions and limitations on human minds. Kant's 1781 book "Critique of Pure Reason (Kritik der reinen Vernunft)" inspired Nelson to go down the path of critical philosophy, and later followed the works of post-Kantian philosopher Fries who had also followed Kant's work. Although his 1904 dissertation "Jakob Fries and his Youngest Critics" ("Jakob Friedrich Fries und seine jüngsten Kritiker") was successful, he had trouble in his early academic years. One such failed dissertation was his "Die kritische Methode und das Verhältnis der Psychologie zur Philosophie" (The Critical Method and  the Relationship of Psychology to Philosophy). Nelson continued defending Fries' philosophy and ideas by publishing a "neue Folge" (new series) of "Abhandlungen der Fries'schen Schule" (1904) with Gerhard Hessenberg and mathematician Karl Kaiser. It was here that Nelson and these same friends created the "Jakob-Friedrich-Fries-Gesellschaft" (Jakob Friedrich Fries Society) to promote critical philosophy. In 1922, Nelson founded the "Philosophisch-Politische Akademie" (Philosophical-Political Academy or PPA) as a "Platonic Academy" and non-profit association, which was abandoned soon after the Nazis banned it, but re-established in 1949. It still stands today for political discussions between philosophers  and politicians, and was supported financially by the "Gesellschaft der Freunde der Philosophisch-Politischen Akademie" (Society of Friends of the Philosophical-Political Academy or GFA). They started working with an education center called "Landerziehungsheim Walkemühle", founded in 1921 by a support of Nelson, progressive teacher Ludwig Wunder (1878–1949). Although Wunder left it shortly after in 1924, educator and co-worker of Nelson, Minna Specht, took over, with the help of journalist and author Mary Saran. Animal rights. Nelson was an early advocate of animal rights and a vegetarian. His lecture "Duties to Animals" was published posthumously in Germany in 1932  and included in his book "A System of Ethics" (translated in 1956) and reprinted in the book "Animals, Men and Morals" in 1972. Career. Ready to form new ideas, Nelson founded the Neo-Friesian School in 1903, with some well-known members, such as: Other notable people, such as philosopher Kurt Grelling and mathematician Richard Courant (student of Hilbert), joined after its foundation. A larger list of ISK members and similar can be seen in the list of Germans who resisted Nazism. In 1909 he habilitated at the University of Göttingen and became "Privatdozent" there. He later worked there as  a professor from June 1919 until his death on 29 October 1927. Internationaler Sozialistischer Kampfbund (ISK). The "Internationaler Jugendbund" (International Youth Federation or IJB) was founded in 1917 by Nelson and Minna Specht. In 1918, Nelson became a brief member of the Independent Social Democratic Party (USPD) before becoming a member of the Social Democratic Party (SPD) from 1923–1925, when he was ultimately excluded. As a result, together with Minna Specht, he founded the Internationaler Sozialistischer Kampfbund "("ISK; "International Socialist Militant League") in 1925, merging it with the IJB by taking over its publishing label, "Öffentliches Leben". The socialist journalist  Willi Eichler succeeded Nelson as president of the ISK after his death. Eichler and Specht would both sign the 1932 "Urgent Call for Unity" ("Dringender Appell für die Einheit") in the ISK's official newspaper, "Der Funke". It called for Germany's Social Democratic Party (SPD) and Communist Party (KPD) to create a left-wing united front in order to thwart the Nazis. After the Nazi's defeat in 1945, the ISK was merged with the SPD with the agreement met on 10 December 1945, between the chairman of the ISK (Will Eichler) and chairman of the SPD (Kurt Schumacher ). However, the ISK continued to be active in the resistance against Nazism. A British affiliate of the ISK was created (lasted from the 1920s to the 1950s) in the United Kingdom called the Socialist Vanguard Group. Among Leonard Nelson's students and political companions in the International Socialist Kampfbund were: Personal life. Leonard Nelson was the son of lawyer Heinrich Nelson (1854–1929) and artist Elisabeth Lejeune Dirichlet (1860–1920), granddaughter of mathematician Peter Gustav Lejeune Dirichlet and descendant of Jewish philosopher Moses Mendelssohn. Nelson married his wife, Elisabeth Schemmann (1884–1954), in 1907, but divorced in 1912 after she baptised their son  Gerhard David Wilhelm Nelson (1909–1944) in the Lutheran Church. Nelson's wife is notable for marrying Paul Hensel in 1917. His granddaughter, Maria Nelson, and Maria's daughter, Rachel Urban, both visited his grave in the summer of 1997. Although Nelson was baptised as a Protestant at the age of five on 13 June 1887, his refusal to baptise his son and divorce was a big change based on his Jewish ancestry. He even resigned from the Evangelical Church in 1919. Death. He was an insomniac and died at a young age from pneumonia, and was buried at a Jewish  cemetery in Melsungen alongside his father Heinrich. Nelson's ideas continued to have an impact upon German socialism and communism in Nazi Germany as the ISK's members became active in the left-wing resistance to Nazism. Bibliography. Nelson published numerous books and papers, often with the help of other philosophers and mathematicians. He was later critical of Georg Wilhelm Friedrich Hegel in his work "Progress and Regress in Philosophy" ("Fortschritte und Rückschritte der Philosophie"). He is also known for defending the idea of animal rights in his work "System of Philosophical Ethics and Pedagogy" ("System der philosophischen Ethik und  Pädagogik") published in 1932, with the help of his assistant Grete Hermann (also part of the ISK) and Minna Specht. Some of his works are already mentioned above, but some others, available in the Internet Archive (and other websites, if not available there), include: Section::::"Gesammelte Schriften in neun Bänden". English translation: "Collected Writings in Nine Volumes". It was published by Paul Bernays and "Felix Meiner Verlag" (a German scientific publishing house in philosophy), in Hamburg 1970-1977;