The Internationaler Sozialistischer Kampfbund (ISK) was a political organization founded by Göttingen philosopher Leonard Nelson and educator Minna Specht.
[1] Nelson and Specht had previously founded the International Socialist Youth League (YSIL) in 1917, which was supported by Albert Einstein.
He advocated a brand of socialism that was ethically motivated, anti-clerical and anti-Marxist, but also undemocratic and included strict vegetarianism and a defense of animal rights.
Nelson moved his main published works there as well, his philosophical and political series Öffentliches Leben and his 1904 treatises, "Abhandlungen der Fries’schen Schule, Neue Folge", re-reasoned with mathematician Gerhard Hessenberg and physiologist Karl Kaiser, and which, after Nelson's death, was continued by Nobel Prize winner Otto Meyerhof, sociologist Franz Oppenheimer and Minna Specht until 1937.
With the growing electoral success of the Nazis at the end of the Weimar Republic, the ISK founded the newspaper, Der Funke to confront the situation.
Calling for unity and support of the SPD and the KPD in order to thwart further gains by the Nazis, it was signed by 33 leading German intellectuals, including scientists Albert Einstein, Franz Oppenheimer, Emil Gumbel, Arthur Kronfeld, the artist Käthe Kollwitz, writers Kurt Hiller, Erich Kästner, Heinrich Mann, Ernst Toller and Arnold Zweig and many others.
The ISK was therefore able to continue its resistance work, helping political refugees leave the country, conducting sabotage and distributing leaflets.
Fritz Eberhard, who was in the ISK until 1939, was a member of the Parlamentarischer Rat ("Parliamentary Council") and was involved in writing the postwar constitution, including the right to conscientious objector status in the new laws of the Federal Republic of Germany.