In the last three decades, we in the West have seen nationalism turn from an apparently progressive force, as in Cuba, Vietnam, and many countries in Africa, into a negative force of degenerating chaos, as in Yugoslavia, the Soviet Union, Sri Lanka, and Rwanda. Elsewhere, during the same decades, the record of nationalism has been, or at least been perceived to have been, more mixed, for example in Belgium, Canada, and India. The assessments themselves are uncertain and suspect, however. Maybe nationalism was not so clearly progressive or so clearly retrogressive where we had previously thought it so. Maybe we misjudge its ambivalence elsewhere. Maybe we are not even dealing with the same kind of phenomenon.
More generally, we have yet to understand the role of nationalism in two world wars and countless imperialist incursions. We have only the vaguest ideas of its connection to social ideologies and movements like racism, fascism, and Nazism and little understanding of its relevance to economic systems like capitalism and socialism.