Nelson, Leonard, 1882-1927

Leonard Nelson (/ˈlɛnərd ˈnɛlsən/; German: [ˈnɛlzɔn]; 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.[ 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.

Leonard Nelson was the son of lawyer Heinrich Nelson (1854–1929) and artist Elisabeth Lejeune Dirichlet (1860–1920),[17] 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.[18] Nelson's wife is notable for marrying Paul Hensel in 1917.[19] His granddaughter, Maria Nelson, and Maria's daughter, Rachel Urban, both visited his grave in the summer of 1997.[20]

Although Nelson was baptised as a Protestant at the age of five on 13 June 1887,[21] 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.[22]