Once, Mad Men ruled advertising. They’ve now been eclipsed by Math Men—the engineers and data scientists whose province is machines, algorithms, pureed data, and artificial intelligence. Yet Math Men are beleaguered, as Mark Zuckerberg demonstrated when he humbled himself before Congress, in April. Math Men’s adoration of data—coupled with their truculence and an arrogant conviction that their “science” is nearly flawless—has aroused government anger, much as Microsoft did two decades ago.

The power of Math Men is awesome. Google and Facebook each has a market value exceeding the combined value of the six largest advertising and marketing holding companies. Together, they claim six out of every ten dollars spent on digital advertising, and nine out of ten new digital ad dollars. They have become more dominant in what is estimated to be an up to two-trillion-dollar annual global advertising and marketing business. Facebook alone generates more ad dollars than all of America’s newspapers, and Google has twice the ad revenues of Facebook.

In the advertising world, Big Data is the Holy Grail, because it enables marketers to target messages to individuals rather than general groups, creating what’s called addressable advertising. And only the digital giants possess state-of-the-art Big Data. “The game is no longer about sending you a mail order catalogue or even about targeting online advertising,” Shoshana Zuboff, a professor of business administration at the Harvard Business School, wrote on faz.net, in 2016. “The game is selling access to the real-time flow of your daily life—your reality—in order to directly influence and modify your behavior for profit.” Success at this “game” flows to those with the “ability to predict the future—specifically the future of behavior,” Zuboff writes. She dubs this “surveillance capitalism.”

However, to thrash just Facebook and Google is to miss the larger truth: everyone in advertising strives to eliminate risk by perfecting targeting data. Protecting privacy is not foremost among the concerns of marketers; protecting and expanding their business is. The business model adopted by ad agencies and their clients parallels Facebook and Google’s. Each aims to massage data to better identify potential customers. Each aims to influence consumer behavior. To appreciate how alike their aims are, sit in an agency or client marketing meeting and you will hear wails about Facebook and Google’s “walled garden,” their unwillingness to share data on their users. When Facebook or Google counter that they must protect “the privacy” of their users, advertisers cry foul: You’re using the data to target ads we paid for—why won’t you share it, so that we can use it in other ad campaigns?

This preoccupation with Big Data is also revealed by the trend in the advertising-agency business to have the media agency, not the creative Mad Men team, occupy the prime seat in pitches to clients, because it’s the media agency that harvests the data to help advertising clients better aim at potential consumers. Agencies compete to proclaim their own Big Data horde. W.P.P.’s GroupM, the largest media agency, has quietly assembled what it calls its “secret sauce,” a collection of forty thousand personally identifiable attributes it plans to retain on two hundred million adult Americans. Unlike Facebook or Google, GroupM can’t track most of what we do online. To parade their sensitivity to privacy, agencies reassuringly boast that they don’t know the names of people in their data bank. But they do have your I.P. address, which yields abundant information, including where you live. For marketers, the advantage of being able to track online behavior, the former senior GroupM executive Brian Lesser said—a bit hyperbolically, one hopes—is that “we know what you want even before you know you want it.”

Worried that Brian Lesser’s dream will become a nightmare, ProPublica has ferociously chewed on the Big Data privacy menace like a dog with a bone: in its series “Breaking the Black Box,” it wrote, “Facebook has a particularly comprehensive set of dossiers on its more than two billion members. Every time a Facebook member likes a post, tags a photo, updates their favorite movies in their profile, posts a comment about a politician, or changes their relationship status, Facebook logs it . . . When they use Instagram or WhatsApp on their phone, which are both owned by Facebook, they contribute more data to Facebook’s dossier.” Facebook offers advertisers more than thirteen hundred categories for ad targeting, according to ProPublica.

Google, for its part, has merged all the data it collects from its search, YouTube, and other services, and has introduced an About Me page, which includes your date of birth, phone number, where you work, mailing address, education, where you’ve travelled, your nickname, photo, and e-mail address. Amazon knows even more about you. Since it is the world’s largest store and sees what you’ve actually purchased, its data are unrivalled. Amazon reaches beyond what interests you (revealed by a Google search) or what your friends are saying (on Facebook) to what you actually purchase. With Amazon’s Alexa, it has an agent in your home that not only knows what you bought but when you wake up, what you watch, read, listen to, ask for, and eat. And Amazon is aggressively building up its meagre ad sales, which gives it an incentive to exploit its data.

Data excite advertisers. Prowling his London office in jeans, Keith Weed, who oversees marketing and communications for Unilever, one of the world’s largest advertisers, described how mobile phones have elevated data as a marketing tool. “When I started in marketing, we were using secondhand data which was three months old,” he said. “Now with the good old mobile, I have individualized data on people. You don’t need to know their names . . . You know their telephone number. You know where they live, because it’s the same location as their PC.” Weed knows what times of the day you usually browse, watch videos, answer e-mail, travel to the office—and what travel routes you take. “From your mobile, I know whether you stay in four-star or two-star hotels, whether you go to train stations or airports. I use these insights along with what you’re browsing on your PC. I know whether you’re interested in horses or holidays in the Caribbean.” By using programmatic computers to buy ads targeting these individuals, he says, Unilever can “create a hundred thousand permutations of the same ad,” as they recently did with a thirty-second TV ad for Axe toiletries aimed at young men in Brazil. The more Keith Weed knows about a consumer, the better he can aim to target a sale.

Engineers and data scientists vacuum data. They see data as virtuous, yielding clues to the mysteries of human behavior, suggesting efficiencies (including eliminating costly middlemen, like agency Mad Men), offering answers that they believe will better serve consumers, because the marketing message is individualized. The more cool things offered, the more clicks, the more page views, the more user engagement. Data yield facts and advance a quest to be more scientific—free of guesses. As Eric Schmidt, then the executive chairman of Google’s parent company, Alphabet, said at the company’s 2017 shareholder meeting, “We start from the principles of science at Google and Alphabet.”

They believe there is nobility in their quest. By offering individualized marketing messages, they are trading something of value in exchange for a consumer’s attention. They also start from the principle, as the TV networks did, that advertising allows their product to be “free.” But, of course, as their audience swells, so does their data. Sandy Parakilas, who was Facebook’s operations manager on its platform team from 2011 to 2012, put it this way in a scathing Op-Ed for the Times, last November: “The more data it has on offer, the more value it creates for advertisers. That means it has no incentive to police the collection or use of that data—except when negative press or regulators are involved.” For the engineers, the privacy issue—like “fake news” and even fraud—was relegated to the nosebleed bleachers.