Imperialism is not a word for scholars. LordHailey, 1940
Imperialism was not in the mainstream of scholarly literature on world politics when Halley, author of the monumental African Survey, made his remark, nor is it today. Historians have studied individual empires and colonies, but most abjure an "ism," a general process and theory. International relations scholars, for their part, tend to place imperialism in a minor position, as one of many possible policies that a powerful state can pursue.
This relative neglect has several sources. Imperial rule involves not only international relations but also the domestic politics of both the subject country (the periphery) and the ruling state (the metropole). In the study of imperialism, therefore, international politics blends into comparative politics. Equally disorienting for current scholarship, empire turns on their heads the central insights of international relations theorists. Imperialism's foundation is not anarchy, but order, albeit an order imposed and strained. Comparative politics, on the other hand, concerned with independent political units, recognizes imperialism as at best one minor influence among many in shaping a state. Empire and imperialism are indeed not "words" for scholars in these disciplinary traditions.
Lord Hailey's statement is unassailable in practical terms. It is clear, however, that he strongly intended his "is not" to mean "ought not to . . .