Nelson, Leonard, 1882–1927, German philosopher. On the faculty of the Univ. of Göttingen from 1909, he was interested in the use of critical method to establish a scientific foundation for philosophy and in the systematic development of philosophical ethics. Nelson viewed Immanuel Kant's Critique of Pure Reason as a treatise on method, and he further developed the thought of Jakob Friedrich Fries, the only post-Kantian who had adopted that approach. Nelson's work in the area of ethics proceeded from a faith in systematic, critical reasoning, on which the values of his system are based. His concern with ethical standards and the question of how human freedom could be reconciled with natural necessity led him to practical undertakings, including the formation of his own political organization and his own school for political education. Among his works that have been translated are Socratic Method and Critical Philosophy (1949), System of Ethics (1956), Critique of Practical Reason (1970), and Progress and Regress in Philosophy: From Hume and Kant to Hegel and Fries (1970).