Leonard Nelson (July 11, 1882 in Berlin – October 29, 1927 in Göttingen) was a German mathematician and philosopher. He was part of the Neo-Friesian School and a friend of the mathematician David Hilbert, and devised the Grelling–Nelson paradox with Kurt Grelling.
During his doctorate at Georg August University of Göttingen he was advised by Julius Baumann, and his dissertation was titled Jakob Fries and his Youngest Critics (Jakob Friedrich Fries und seine jüngsten Kritiker). He was critical of Georg Wilhelm Friedrich Hegel in his work, Progress and Regress in Philosophy (Fortschritte und Rickschritte in der Philosophie). He is also known for defending the idea of animal rights in his work System of Ethics (System der philosophischen Ethik und Pädagogik). Together with Minna Specht he was the founder of Internationaler Sozialistischer Kampfbund.
- Nelson, Leonard, System of Ethics, Yale University Press, New Haven, 1956, p. 142.
- Biography from the Friesian School
- Biography from the SFCP site
- The Socratic Method (Die sokratische Methode) by Leonard Nelson, translated by Thomas K. Brown III