Intellectual setting
Luxemburg was active in the German Social Democratic Party (SPD) during its rise as Europe's largest socialist party, engaging the internal revisionism debate with Eduard Bernstein around 1900, and broke decisively with the SPD leadership over its support for war credits in 1914. She co-founded the Spartacus League with Karl Liebknecht, was repeatedly imprisoned for anti-war agitation, and was murdered by right-wing Freikorps paramilitaries in January 1919 during the suppression of the Spartacist uprising in Berlin.
Key ideas
Critique of revisionism
Against Eduard Bernstein's argument that capitalism could be gradually reformed into socialism through parliamentary and trade-union activity, Luxemburg argued in Reform or Revolution (1900) that reforms are valuable for organizing the working class but cannot by themselves abolish capitalism, which requires revolutionary transformation.
The mass strike and revolutionary democracy
Luxemburg theorized the spontaneous mass strike as a vehicle of proletarian self-organization in The Mass Strike, the Political Party and the Trade Unions (1906), and in The Russian Revolution (1918) argued that socialism without freedom of the press, assembly, and open political contestation degenerates into bureaucratic dictatorship, insisting that freedom must always include "freedom for the one who thinks differently."
Legacy
Luxemburg's theory of imperialism and her critique of both reformist and authoritarian socialism made her a central reference point in later Marxist debate, from the New Left's interest in spontaneous mass action to democratic-socialist critiques of Soviet communism, and she remains an iconic figure in the history of European socialism.