In their bestselling book Merchants of Doubt, Naomi Oreskes and Erik M. Conway revealed the origins of climate change denial. Now, they unfold the truth about another disastrous dogma: the "magic of the marketplace." In the early 20th century, business elites, trade associations, wealthy powerbrokers, and media allies set out to build a new American orthodoxy: down with "big government" and up with unfettered markets. With startling archival evidence, Oreskes and Conway document campaigns to rewrite textbooks, combat unions, and defend child labor. They detail the ploys that turned hardline economists Friedrich von Hayek and Milton Friedman into household names; recount the libertarian roots of the Little House on the Prairie books; and tune into the General Electric-sponsored TV show that beamed free-market doctrine to millions and launched Ronald Reagan's political career. By the 1970s, this propaganda was succeeding. Free market ideology would define the next half-century across Republican and Democratic administrations, giving us a housing crisis, the opioid scourge, climate destruction, and a baleful response to the Covid-19 pandemic. Only by understanding this history can we imagine a future where markets will serve, not stifle, democracy.