It is possible to distinguish between empire, as a form of political order, and imperialism, as a process of aggressive expansion. Mill's liberalism allows for a legitimate empire, in which a civilized state rules a less civilized foreign people paternalistically to prepare them for liberal democratic self-rule. However, it rejects paternalistic imperialism, in the sense of aggression designed to establish such an empire. Apparent textual evidence to the contrary really demonstrates Mill's commitment to three distinct theses: that imperialism may benefit those subject to it, and this can mitigate its evil; that it is easier to justify non-aggressive, empire-creating wars of conquest in response to aggression by barbarian powers; and finally, that civilized states are justified in engaging distant uncivilized peoples non-aggressively, even though the latter's aggressive tendencies mean that such engagement renders empire-justifying wars more likely.

帝国主义是一种政治秩序的形式，而帝国主义是一种侵略扩张的过程。密尔的自由主义允许建立一个合法的帝国，在这个帝国中，一个文明的国家以家长式的方式统治着不那么文明的外国人民，以使他们为自由民主自治做好准备。但是，它拒绝家长式帝国主义，在侵略的意义上，旨在建立这样一个帝国。与此相反的明显文字证据确实证明了密尔对三个不同论点的承诺：帝国主义可能使臣民受益，这可以减轻其邪恶；更容易证明非侵略性的、建立帝国的征服战争是为了应对野蛮列强的侵略；最后，文明国家有理由以非侵略性方式与遥远的未文明人民交战，尽管后者的侵略倾向意味着这种交战使帝国更有可能发生战争。