Alan Reynolds writes at National Review Online about critical problems within common arguments against Big Tech.

Facebook, Amazon, Apple, and Google are being threatened with costly antitrust suits and possible dismemberment for having unfairly secured a “monopoly” of something or other. This crusade has spurred congressional hearings and bills, in addition to several executive orders from President Biden. This political campaign reflects, as the Wall Street Journal put it, “a new Democratic emphasis on restraining the nation’s most powerful companies.”

The new trustbusters are hoping to remake antitrust law into a lawyers’ combat sport with unpredictable ad hoc rules — antitrust for fun and profit. A New York Times headline predicts good times for key players: “Boom Times for Lawyers as Washington Pursues Big Tech.” But overheated politicians and opportunistic lawyers may not be enough to keep these lucrative games going for long. Sooner or later, all the scattergun monopoly charges will have to confront logic and evidence.

In the scramble to drum up antitrust objections to the four alleged Big Tech monopolies, congressional aides and compliant journalists invariably make two crucial mistakes. First, they adopt indefensibly narrow definitions of the markets that have supposedly been monopolized. Second, they confuse popularity with dominance.

Consider that first stumbling block, which requires defining the relevant market. Whenever any firm is accused of having a monopoly, the first question to ask is: “A monopoly of what?” Facebook shows how hard it can be to answer such a seemingly easy question.

In dismissing an ill-fated Federal Trade Commission antitrust suit against Facebook, U.S. District Judge James Boasberg noted that “the FTC alleges only that Facebook has ‘maintained a dominant share of the U.S. personal social networking market (in excess of 60%)’ since 2011.” He added that “the Court is . . . unable to understand exactly what the agency’s ‘60%-plus’ figure is even referring to, let alone able to infer the underlying facts that might substantiate it.”