Over a century ago, the United States entered the Progressive Era, which came on the heels of what Mark Twain and Charles Dudley Warner dubbed the Gilded Age. The latter was marked by the rise of large corporate interests, fabulously wealthy "robber barons," and technological innovation. The former, in some sense a reaction to perceived Gilded Age excess, spawned an array of political and legal reforms, including antitrust attacks on ubiquitous business trusts. In his 1901 novel "The Octopus," Frank Norris played to the public's fears of these trusts and their surreptitious and growing influence:

[T]he Trust was silent, its ways inscrutable, the public saw only results. It worked on in the dark, calm, disciplined, irresistible. Abruptly Dyke received the impression of the multitudinous ramifications of the colossus. Under his feet the ground seemed mined; down there below him in the dark the huge tentacles went silently twisting and advancing, spreading out in every direction, sapping the strength of all opposition, quiet, gradual, biding the time to reach up and out and grip with a sudden unleashing of gigantic strength.

These days, one need only pick up most any newspaper to read we've entered a second Gilded Age countered by a new Progressive Era. Just last year, we learned the Antitrust Division of the Department of Justice, the Federal Trade Commission, Congress, and numerous states attorneys general had opened investigations of large technology companies, including Google, Facebook, and Amazon. Nothing has come of these investigations so far, but the sheer number of the investigations harkens back to early 20th century assaults on Standard Oil, American Tobacco, and U.S. Steel.

At the level of antitrust theory, a debate is playing out between two groups:  the New Brandeis (also known as Hipster Antitrust) movement and proponents of the economics-influenced status quo. Many practitioners and scholars have entered the fray, but Lina Khan, who authored an influential article as a Yale Law student and is currently majority counsel to the U.S. House of Representatives Subcommittee on Antitrust, Commercial, and Administrative Law, and Joshua Wright, a former FTC commissioner and current law professor at George Mason University's Scalia Law School, fairly represent the two strands of thought.

Khan's overarching argument is that current antitrust orthodoxy, which places great emphasis on "consumer welfare" in the form of low prices, misapprehends the dynamics of market power in the modern economy. More specifically, she posits that that "current doctrine underappreciates the risk of predatory pricing and how integration across distinct business lines may prove anticompetitive." In her view, this worry is heightened in the context of online platforms and their powerful network effects. Her concerns are essentially two: platform markets valorize growth over profits, which makes predation more "rational" than otherwise thought, and the platforms are critical intermediaries whose information collection practices place them in the position to exploit rivals and undermine them as competitors. From this vantage, Khan sees problems in received antitrust wisdom, ranging from a modern suspicion of leveraging and predation theories, assumptions regarding the relative ease of market entry and exit barriers, and generally neutral-to-favorable treatment of vertical and conglomerate integration.

Wright counters that "the development of the antitrust laws over the past half century has been a remarkable and positive development for the economy and consumers." He points to an antitrust past in which "antitrust laws employed confused doctrines that pursued populist notions and often led to contradictory results that purported to advance a variety of social and political goals at the expense of American consumers." Representative of this historical mode of analysis is Learned Hand's pronouncement in United States v. Aluminum Co. of America that "great industrial consolidations are inherently undesirable, regardless of their economic results," which is to say, in essence, big is bad. But by the 1960s, the "Chicago School" of economics advanced powerful arguments that the purpose of antitrust laws is to promote price cuts, output increases and research and development, not to protect competitors from more efficient rivals.

The New Brandeis rebuttal is, in part, that the "coherent, principled, and workable body of law" Wright points to is not really so. That school's argument is that antitrust rules were actually much clearer 50 years ago, presumably because so many more kinds of conduct were deemed per se illegal. They thus suggest "clear rules must govern mergers, dominant firm conduct, and vertical restraints and replace the current rule of reason review and other amorphous standards, which heavily tilt the scales in favor of defendants." There is some truth to the complaint that lackluster results and enormous litigation costs under the "rule of reason" have mostly stifled private antitrust enforcement of all but hard-core violations (such as price fixing). But it's also true a regime under which most vertical distribution restraints are deemed per se illegal can condemn conduct that is actually pro-competitive and consumer-friendly.

So where does this leave us? Wright is surely right that the New Brandeis group's most forceful claims (e.g., that antitrust under enforcement has contributed to wealth inequality) cannot be sustained without more empirical support. And as Wright readily concedes, there is no shortage of scholarly debate as to how to improve antitrust enforcement within existing frameworks and without discarding the consumer-welfare standard. But as Khan and her fellow travelers remind us, there may be a social good in having lots and lots of competitors. Now whether social restructuring on this order is best work for antitrust law is a discussion for another day.

Randy Gordon is co-chairman of the antitrust practice group and a partner with Barnes & Thornburg and executive professor of law and history at Texas A&M University.