How and why do party ideologies change over time? And how should social scientists approach the study of ideology in general? In Ideas of Power, Verlan Lewis takes up these important questions and delivers thought-provoking answers that improve our understanding of American party ideology development.

Lewis argues that control of government institutions is a critical factor in driving party ideological change. Whatever they may espouse during campaigns, once party actors take control of government, they seek to maximize and expand the boundaries of their power. Presidents expand the reach of the executive; congressional co-partisans facilitate it; judicial appointees (nominated and confirmed by partisans) acquiesce to it. Over the long term (at least two presidential terms), party ideology—“a system of ideas shared by party members that shapes the way they think, talk, and act” (p. 28)—is reshaped to justify the behavior of the in-party. Foundational principles remain, but parties’ theories of governance, intervention, and their specific policy positions are retrofitted to legitimate the actions they have taken. The out-party, meanwhile, to remain competitive and make an effective bid to retake power, likewise revises its views on governance and the appropriate exercise of authority, calling for restraint and extolling the