Every subsequent culture-war battle, in Caldwell’s account — the debates over feminism and gay marriage, transgender rights and immigration — follows the lines of this constitutional division. The new constitutionalists are constantly discovering new rights and empowering courts and bureaucracies to enforce them; the old constitutionalists object, win a few elections on the objection and then find themselves defeated nonetheless. And this pattern of defeat is responsible, he implies, for the Trumpian turn: After so many failures to defend the old Constitution, Trump-era conservatives are embracing the logic of the new one, choosing white-identity politics because in “the new constitutional dispensation that began in 1964,” group identities are the only ones that count.

Caldwell’s book is noteworthy for being a conservative account that effectively reinforces a liberal ideological narrative. It is usually liberals who argue that on every new culture-war battlefield their side is just extending Martin Luther King Jr.’s vision, while conservatives respond that the civil rights acts were supposed to correct a specific historical injustice and their application to debates over gender or marriage or abortion or the rights of illegal immigrants warps that purpose. Caldwell shrugs off this idea as a pleasant illusion; in his account the original critics of civil rights legislation were probably correct to warn against its revolutionary implications, which include the steady subsequent advance of cultural progressivism, an enormous expansion of deficit spending and the economic abandonment and cultural vilification of the white male working class.

And this is where Caldwell’s account becomes unpersuasive in its turn. He depicts federal economic policymaking after the civil rights era as a hugely expensive attempt at “integrating Americans by race and sex,” a project paid for after Ronald Reagan by deficits rather than transfers. But as Wesley Yang points out in a review of “The Age of Entitlement” for The Washington Examiner, there’s little evidence that American public policy actually transfers lots of money from whites to minorities; the spending that Reagan’s deficits funded was for the military and old-age entitlements, both of which flowed far more into white pocketbooks than black ones. Nor were the economic policies that have arguably harmed working class whites the most somehow a necessary extension of civil rights legislation: China’s entry into the World Trade Organization, to choose one signal example, was not somehow foreordained when L.B.J. set pen to paper.

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So if Caldwell’s book supplements and corrects Klein’s, by giving a clearer sense of the ideological stakes involved in post-1960s polarization, his account needs to be corrected and supplemented in its turn. And a third new book, Michael Lind’s “The New Class War: Saving Democracy From the Managerial Elite,” does an important part of that work, by explaining an aspect of our present polarization that can’t be traced to specifically American racial fears or constitutional debates: Namely, the way that our populist-era divisions increasingly mirror Europe’s, with the same exodus of downscale voters from left-of-center parties, the same polarization by education and class.

In Lind’s account, Caldwell’s story about the advance of social liberalism through bureaucratic and judicial power is just a subsidiary of the more important story, the post-1970s consolidation of economic power by a “managerial” upper class. The liberalism of Bill Clinton and Barack Obama isn’t an ideology of white disempowerment, in his account, so much as a solvent that weakens any institution — from churches and families to union shops and local industries — that might grant real power to groups outside the gilded city, the Silicon Valley bubble, the Ivy League gate. And together with its center-right partner in crime, Reagan-Thatcher libertarianism, this liberalism’s policy choices — economic and social permissiveness, effectively conjoined — created a new class divide, between thriving meritocratic hubs and a declining and demoralized heartland, that explains both the frequency of populist irruptions and their consistent futility.

But even as he acknowledges the faults of populism, Lind treats the class-war aspect of polarization as a potentially positive development, because he hopes that it will create a real political coalition for the losers of neoliberal era — a socially conservative, economically left-leaning constituency that’s numerous but often homeless. Making such a coalition constructive rather than just disruptive may be impossible, but it’s the only way he sees to escape neoliberal oligarchy and bring our class war to an end with a negotiated peace.