Nationalism defeated the Second International yet enabled the Third International.

Evidence

What the Marxists did not understand about the political and ideological phenomenon of nationalism is that it was not (and is not) a historical aberration (of proletarian internationalism). Nor is it necessarily the contrary: a developmental stage of internationalism. Nationalism defeated the Marxism of the Second International (World War I), but ironically, was a basis of the Marxism of the Third International (the Russian revolutions; Stalin’s socialism in one country; the conditions for membership in the Comintern), yet its primary world-historical significance was denied. — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 368

Categorization

• DEEPTHINKING: Dense paradox: the same ideology that broke one Marxism founded another — a genuinely layered claim about how nationalism both defeats and constitutes socialist movements.