Of all the tech chieftains who’ve learned to love Donald Trump’s authoritarianism, Palantir’s Alex Karp seems the most befuddling. “My biggest fear is fascism,” he told Michael Steinberger, author of a new biography of Karp, in 2019. The fragility of liberal democracy was, in Steinberger’s telling, one of Karp’s preoccupations. He moved to Germany for graduate school, hoping to understand, as Steinberger puts it, how “a pillar of European civilization” had “descended into barbarism.” He wrote his Ph.D. dissertation on the rhetoric of fascism, focusing particularly on a 1998 speech by the German novelist Martin Walser complaining that Holocaust remembrance...