When Bourne denounced Lippmann and his ilk, he leveled a charge that has dogged liberal elites ever since. He skewered them as disingenuous and greedy for power. They supported immoral policies for their own purposes—which they considered lofty—when they should have known better. Decades later, the broadsides against the liberal hawks who lent their imprimatur to the Iraq War echoed this sentiment. And Bourne’s indictment anticipated the accusation of callous cynicism directed at Bill Clinton’s criminal-justice policy, seen as a ploy to win back white working-class voters. Barack Obama’s response to the financial crisis, which let bankers slip away unpunished for their misdeeds, roused similar ire.

Over his career, Lippmann provided plenty of examples that validated the core of Bourne’s critique. As Snyder tells the story, Felix Frankfurter turned on his roommate from the House of Truth for similar reasons. Frankfurter worked tirelessly to save the anarchists Sacco and Vanzetti from the accusations that sent them to death row. He eloquently transformed their fate into the quintessential liberal crusade of the ’20s—and was apoplectic that when he tried to enlist Lippmann in his effort, he struggled to rouse him from his icy evenhandedness.

Yet however valid Bourne’s reasons for scything Lippmann and the liberal intellectuals were, there was also something juvenile about his attack. Indeed, Bourne himself might have described his defiance that way. His earliest essays advocated youthful rebellion—and denounced the oppressive hold that the middle-aged exerted over society. “Youth is the incarnation of reason pitted against the rigidity of tradition,” he wrote. His beef with his seniors had some of the glibness of a teenage tantrum, and so did his attack on the liberal intellectuals. He simply couldn’t countenance the notion that Lippmann might want to lead American policy in a more humane, internationalist direction out of motives that were public-minded as well as vainglorious. It’s true that Lippmann took smug satisfaction in his audiences with the president and in the attentions of Wilson’s most trusted adviser, Colonel Edward House. Yet he didn’t hesitate to brutally—and influentially—turn against Wilson for botching the aftermath of the war.

Bourne will always make a readier hero than Lippmann. In the last days of 1918, as the war drew to a close, he died of the Spanish flu—a tragic end that had nothing to do with the intellectual exile he endured during the war, but that added to his aura of martyrdom. Bourne spent the last year of his life pushed out of magazines that had once welcomed him, with hardly any outlets for his thunderous denunciations. His death froze him in the fresh-faced state of youthful rebelliousness that he celebrated.

The radicals of the prewar years are good grist for inspiring yarns. But to what end? Many of the protests of these years were aesthetic gestures, statements of nonconformity rather than expressions of a political program. John Reed, Lippmann’s Harvard classmate and another of McCarter’s protagonists, was a burly adventurer who went off to chronicle the Russian Revolution. The thrilling firsthand account he produced, Ten Days That Shook the World, was romantic and admiring. Lenin, who blurbed the book, rewarded Reed for his powerful propaganda by burying him in the wall of the Kremlin. Though you would hardly guess it from McCarter’s tender treatment, Reed’s career is a cautionary tale of the reasons to fear idealism and high-profile protest merely for the sake of rebellion.