Traub would answer that the liberalism whose decline worries him most isn’t the big-D Democrat kind that wants rich people to pay more in taxes, corporations to clean up the environment and the courts to keep abortion legal. Rather, Traub’s biggest worry is the threat Trump poses to the American Republic’s classically liberal pillars, cherished by Republican and Democrat alike: free speech, the rule of law and so on. This is the liberalism that Vladimir Putin said, chillingly, in a recent interview “has become obsolete.” (Trump was quick to agree, though he probably misunderstood what Putin meant.) The most richly reported part of Traub’s book documents the harrowing rise of “illiberal and increasingly authoritarian leaders” in Hungary, Poland and Italy, which predates Trump’s election, and recent worrisome trends in countries like the Netherlands, Austria and the United Kingdom.

Trump, Traub argues correctly, is part of this wave. But he can’t produce any concrete examples of Trump traducing free speech or the rule of law because Trump’s assaults on these citadels are typically rhetorical, expressed on Twitter or in stream-of-consciousness monologues at political rallies. Trump’s real-world attempts to violate established procedures have mostly been blocked, either by his own executive-branch lawyers or by the courts. The most glaring exceptions are in the legal gray area of immigration, where Trump is free to inflict genuine suffering because immigrants can’t claim the citizenship protections the rest of us take for granted. The recently initiated impeachment inquiry may bring to light more grave subversions, but the precipitating event — withholding foreign aid to Ukraine while Trump sought dirt on the Biden family — ended when Congress cried foul.

Trump poisoned “the cognitive or epistemological foundations of liberalism,” Traub writes, by undermining “the very idea of truth by eliminating from it the criterion of factuality.” Well, yes, truth-telling would appear to rank pretty low among Trump’s aspirations. But Republicans were playing epistemological games well before Trump, denying the existence of climate change and evolution, talking up a phony epidemic of election fraud to justify voter restrictions, insisting that tax cuts increased revenues to justify deficit-exploding tax cuts and ordering the F.B.I. to quit tracking far-right domestic terrorism because these fellows really weren’t much of a threat.

It wasn’t Trump but an unnamed senior adviser to President George W. Bush (widely presumed to be Karl Rove) who 15 years ago declared that the press belonged to the “reality-based community,” whereas in the Bush administration “we create our own reality.” Trump merely extended this smug delusion to frontiers his predecessors never thought possible.

But enough about Donald Trump. His depredations would make excellent grist for a study of the crisis in American conservatism (which has been noted by many conservative commentators but hasn’t produced as many books). If liberalism is in crisis, who’s to blame?

Traub tries to blame it, at least partly, on Barack Obama. Obama, Traub writes, “managed to pass the stimulus package, rescue the auto industry, restore faith in the economy and, after a prolonged struggle, pass a massive health care reform package.” (The cad! I’d add that Obama pushed through the first significant financial reform bill since 1933.) “It was an impressive record,” Traub is forced to concede. But Obama “failed” because he “kindled the flames of racial fear and resentment,” not by what he did but by who he was: an African-American liberal with a “foreign-sounding name.” Some of that racial resentment was fanned by a certain publicity-hungry real estate mogul and reality TV star who entered the political arena spouting hateful nonsense that Obama was not American by birth like you or me but African.

Traub’s victim-blaming analysis here is simply wrong. Obama enraging anti-liberals isn’t evidence that he failed. He enraged them because he succeeded, just as the 1968 liberal establishment enraged George Wallace’s followers because it was running the show. In American democracy, any successful exercise of political power will invite backlash. Why rebel against failure?