Advocates of democratic peace theory see the spreading of democracy as helping to mitigate the effects of anarchy. With enough democracies in the world, Bruce Russett thinks that it "may be possible in part to supersede the 'realist' principles (anarchy, the security dilemma of states) that have dominated practice since at least the seventeenth century." John Mueller believes that it is not the spreading of democracy but rather other conditions (e.g., power) that bring about democracy and peace. In consenting with Mueller's argument, Kenneth Waltz notes that "some of the major democracies—Britain in the nineteenth century and the United States in the twentieth century—have been among the most powerful states of their eras."