… is from page 296 of Christopher Achen’s and Larry Bartels’s 2016 book, Democracy for Realists:
In the political sphere, the most salient groups are parties, and the self-justifications that sustain group life are primarily grounded in – and constructed to maintain – partisan loyalties. People tend to adopt beliefs, attitudes, and values that reinforce and rationalize their partisan loyalties. But those loyalties, not belief or ideologies or policy commitments, are fundamental to understanding how they think and act.
DBx: Powerful evidence in support of this argument is the large number of Republicans who today in the United States excuse and apologize for – indeed, who often cheer and now clamor for even more of – Trump’s protectionism and other big, discretionary government ‘policies.’