Leonard Nelson, described by Karl Popper as an "outstanding personality," produced a great quantity of work (collected in the nine volumes of the Gesammelte Schriften) in a tragically short life. The quantity and the tragedy may have both happened because Nelson was an insomniac who worked day and night and exhausted himself into a fatal case of pneumonia.
Nelson's greatest contributions to philosophy were his rediscovery of Jakob Fries, his exposition, systematization, and expansion of Friesian philosophy, the use and theory of Socratic Method in his pedagogy, and his engagement with the mathematical issues of Kantian philosophy in relation to his personal and professional involvement with one of the great mathematicians of the Twentieth Century, David Hilbert (1862-1943). Hilbert's concern with the axiomatization of geometry and all of mathematics strongly paralleled Nelson's work in the Friesian theories of truth and justification. Nelson recognized the important parallel between Hilbert's conception of meta-mathematics and Fries' distinction between critique and metaphysics.
Hilbert is now often overshadowed by later mathematicians; and Hilbert's desire to complete mathematics by reducing it to a finished and closed axiomatic system is now often only mentioned in the context that this was shown to be impossible by Kurt Gödel (1906-1978). However, there would have been no Gödel if Hilbert had not proposed and pursued the axiomatization project in the first place, and the incompleteness of mathematics has in no way forestalled the continued construction of mathematics as an axiomatic system. Indeed, the original axiomatization of geometry in Euclid, elaborated and reformulated by Hilbert himself, is now supplemented by Axiomatic Set Theory, which accomplished the same kind of axiomatization for arithmetic -- serendipitously vindicating Kant, who had held that arithmetic was not analytic and so would require synthetic axioms (efforts to derive arithmetic analytically from logic alone, as in Russell & Whitehead's Principia Mathematica, failed).
Valuable aspects of Nelson's career and relationship with Hilbert are to be found in Constance Reid's biographies of Hilbert and his student Richard Courant (1888-1972) [Hilbert-Courant, Springer-Verlag, 175 Fifth Avenue, New York, NY 10010, 1970, 1976, 1986]. What follows are some passages relevant to Nelson:
Nelson was also a champion of the axiomatic method. His philosophical work treated two main problems: the laying of a scientific foundation for philosophy and the systematic development of philosophical ethics and a "philosophy of right." He was still firmly opposed by Husserl, the philosophy professor; and Hilbert's files contain an extremely bulky item labeled "The Nelson Affair," recording his efforts to obtain an associate professorship for Nelson during this time.
Nelson (who finally did become an associate professor, but not until after the war) later dedicated to Hilbert the three volumes of his Lectures on the foundations of ethics [Vorlesungen über die Grundlagen der Ethik, which begins with the Kritik der praktischen Vernunft, dedicated to Hilbert] -- "an attempt to open up for the sovereign domain of exact science a new province." [Hilbert, pp. 144-45.]
Husserl's place was filled, with Hilbert's backing, by Leonard Nelson; but Courant continued to hold the idea that if such an appointment as that of Weyl was not made, the old "unfriendly" conditions between mathematics and philosophy would continue to exist. In 1922, with the establishment of a separate faculty of mathematics and the natural sciences, Courant apparently negotiated an additional chair for mathematics and offered it to Weyl. [Courant, p. 314.]
Courant's views illuminate one aspect of Nelson's personality: he was a driven and extremely certain sort of man. Indeed, in some matters, Nelson verged on dogmatism, so confident was he of his results. This would have put off many people personally, as it nearly did Courant, but the overall effect, quite fortunate when Nelson's considered views influenced few in academic philosophy, was to attract dedicated students. The work of such students in perpetuating Nelson's memory was invaluable in Germany, where Grete Henry-Hermann and others brought to completion the publication of Nelson's works, in Britain, where the journal Ratio was published and the translation and publication of Progress and Regress in Philosophy [Basil Blackwell, 1970] was undertaken, and in the United States, where L.H. Grunebaum's "Leonard Nelson Foundation" arranged the translation and publication of both Socratic Method and Critical Philosophy [Yale 1949, Dover 1965, Kissinger Publishing, 2008] and the System of Ethics [Yale, 1956] (the Critique of Practical Reason, translated but never published, was made available in bound photocopy in 1970).
Besides his purely philosophical work, Nelson founded a would-be Platonic Academy, the still existing Philosophisch-Politische Akademie, that was the center for his own political party, the grandly (we could even say bombasticly) titled Internationaler Sozialistischer Kampfbund (ISK, "International Socialist Battle/Struggle League"), which, however, did not have much of an independent existence. As a "non-Marxist socialist," in Popper's words, Nelson, who advocated something rather like a Führer Prinzip of political leadership, employed political and economic principles that actually no longer appear worthy. His disparagement of the free market as "anarchy" was part of the now exploded "fatal conceit," in F.A. Hayek's words, that command and control features would ensure macroeconomic efficiency and productivity. Although these issues are still matters of often intense political dispute, as socialist principles die hard in various redoubts, like American universities controlled by "tenured radical" dinosaurs, the economic case is all but settled in theory and practice.
In an age of dishonesty, nihilism, and relativism, the promise of Nelson's great work, both philosophically and personally, is yet to be fulfilled. His premature death blighted the promise of his thought. The unique principles of Friesian epistemology that he recovered were abandoned by his own students. 20th Century philosophy swung between the false alternatives of science and irrationalism, ignoring the promise of Kantian philosophy. And Nelson's own socialism obscured the proper direction and the best use in political economy of Friesian principles. In a new century, The Proceedings of the Friesian School, Fourth Series can at least maintain the hope of redeeming these disappointments.
Leonard Nelson - Critical Natural Philosophy
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.
The Socratic Method, by Leonard Nelson
The Impossibility of the Theory of "Knowledge," by Leonard Nelson
Grete Henry's "The Significance of Behaviour Study for the Critique of Reason," Ratio, Volume XV, No. 2, December 1973
Nelson's Proof of the Impossibility of the Theory of Knowledge, Dr. Kay Herrmann, 2011
Note on Nelson's Axiomatic Diagrams
History of Philosophy
Nelson on Home Page