It all seemed so inevitable: that Jack Dorsey, the C.E.O. and co-founder of Twitter, would appear onstage at last week’s TED ideas conference, in Vancouver; that the conference theme would be “Bigger Than Us,” an ambiguous invocation of either inspiration or fear; that Dorsey, during a session called “Power,” would calmly acknowledge the proliferation of coördinated harassment campaigns, conspiracy theories, and politically motivated misinformation on his company’s platform; that he would speak at length and say nothing new. Dorsey has been on a months-long, semi-apologetic publicity tour. He has met with tech journalists, to promote his company’s shift in focus from growth to “conversation health” (an initiative that has yet to result in concrete changes), and with conservative commentators, to discuss anti-conservative platform bias (the existence of which has not been proved). Throughout, he has taught a sustained master class in conversational redirection and opacity. Dressed in what has recently become a signature monochrome—wrinkled black hoodie, tight black beanie, black Rick Owens “sock sneakers”—Dorsey looked wraithlike against the colorful set at TED, an Edward Gorey character who had lost his way. His beard was long, bushy, eremitic. A small metallic hoop glinted from his left nostril.

Rather than give a typical solo lecture, with its digestible slide deck and premeditated strolling, Dorsey sat for an interview with Chris Anderson, the head of TED, and Whitney Pennington Rodgers, TED’s current-affairs curator. Perched on a gray couch across from his interlocutors, sipping occasionally from a white teacup, Dorsey looked like a teen goth at a family holiday party cornered by well-intentioned relatives who were curious about his post-graduation plans. He was conciliatory, if not contrite, in offering ideas for reform. “If I had to start the service again, I would not emphasize the follower count as much,” he said. “I would not emphasize the ‘like’ count as much. I don’t think I would even create ‘like’ in the first place, because it doesn’t actually push what we believe now to be the most important thing, which is healthy contribution back to the network and conversation to the network, participation within conversation, learning something from the conversation.”

Although Dorsey is not a born entertainer, he does have a propensity for personal broadcast. Some of his life-style decisions have amused and angered the public and, in some corners, prompted questions about his fitness to oversee a major piece of modern social and political infrastructure. In December, he tweeted at length about a ten-day silent retreat that he attended in Myanmar—Vipassana meditation, he wrote, allowed him to “hack the deepest layer of the mind and reprogram it”—without acknowledging that the country’s military was involved in violent persecution of the Rohingya people. Earlier this spring, he shared his excitement about intermittent fasting, prompting comparisons between the so-called biohacking trend that is sweeping Silicon Valley—ice baths, single-meal days—and eating disorders. Even in the famously irreverent tech industry, his fashion choices have inspired discussion about the double standards that exist for men and women, especially those who are black and Latinx, in the workplace.

At TED, Dorsey, already a mellow figure, was almost aggressively low-key, a model of corporate detachment. He seemed far from himself and distant from the concerns of his interlocutors; he hardly resembled the easygoing, enthusiastic, sketchbook-toting figure portrayed in a 2013 Profile for this magazine, which was written during a period when Dorsey was focussed solely on running the financial-services company Square, between his two stints at Twitter.

“How many people do you have working on content moderation?” Anderson asked, during an exchange about violent extremist groups.

“It varies,” Dorsey said, with a small nod. “We want to be flexible on this, because we want to make sure that we’re, No. 1, building algorithms instead of just hiring massive amounts of people, because we need to make sure that this is scalable.”

“How many people do you currently have monitoring these accounts, and how do you figure out what’s enough?” Pennington Rogers pressed.

“They’re completely flexible,” Dorsey said. “Sometimes we associate folks with spam. Sometimes we associate folks with abuse and harassment. We’re going to make sure that we have flexibility in our people so that we can direct them at what is most needed.” Behind Dorsey, a live stream of tweets, marked with the hashtag #askJackatTED, scrolled on two massive screens. “Why haven’t you banned white supremacists on this platform, despite legally having to hide them in Germany?” one user asked. “Why wasn’t Trump suspended on Friday for inciting hate and violence against Rep. Ilhan Omar?” another asked. “Are you willing to materially reduce the number of active users and engagement, the metrics that Wall Street uses to value the company, in order to ‘improve the health of the conversation’?” Chris Sacca, an early investor in Twitter, asked. The questions continued to stream past, unanswered and, for Dorsey, out of sight.

The TED conference, established thirty-five years ago, has long been a way station for tech entrepreneurs on the media circuit. The organization’s video archive—it has since expanded to include many satellite events—is a valuable time capsule. It holds footage of an excitable Jeff Bezos presenting on the future of the Internet, in 2003; of Sergey Brin and Larry Page speaking about the origins of Google, in 2004. (“We have a tremendous ability and responsibility to provide people the right information, and we view ourselves like a newspaper or a magazine,” Page says.) In 2009, Evan Williams, who was then the C.E.O. of Twitter, presented at TED. In a talk titled “The Voices of Twitter Users,” Williams described how usage patterns helped drive product decisions. “What we didn’t anticipate was the many, many other uses that would evolve from this very simple system,” he said, citing neighborly information exchange during California’s 2007 wildfires. “It seems like when you give people easier ways to share information, more good things happen.”

Williams’s talk now registers as an artifact from a simpler Internet epoch. Good things probably still happen on Twitter, from time to time, but the dominant narrative about the platform today focusses on coördinated harassment campaigns, incentivized outrage, and an inconsistently applied moderation policy. While some tech leaders, particularly those operating social networks, are beginning to acknowledge the downsides to what they’ve built, the unfortunate reality is that the tools are working exactly as designed. Social networks, like most tech products, are built for growth, engagement, and acceleration—and are optimized to generate returns for investors and capture as much market share as possible. The toxicity of Twitter is testament to the functionality of the underlying system. To truly reform the platform would require a rejection of the industry’s fundamental values. It would look something like an implosion.

Dorsey has been talking about fixing Twitter for more than a year. As is to be expected, he takes a technologist’s approach to social problems. At TED, he focussed on systems, rather than on the demands of ethics or social responsibility, and talked about leveraging machine learning for moderation. (Like many tech leaders, he speaks about machine learning in vague terms, as if it were magic—a cure-all whose technological underpinnings are far too complex to explain.) He acknowledged some of the implications of optimizing for the “health” of the conversation: doing so would require rejecting many of the engagement metrics that drive product development across the tech industry. Twitter has been working with Cortico, a nonprofit organization affiliated with the M.I.T. Media Lab, from which, it says, it is adopting four new metrics—“shared attention,” “shared reality,” “receptivity,” and “variety of opinion”—to gauge conversational health. “Implicit in all four is the understanding that, as they increase, the conversation gets healthier and healthier,” Dorsey said. And yet the metrics, as described by Dorsey, seem largely value-agnostic; the content of the conversation is left out of the analysis. The “shared reality” metric, for instance, captures “what percentage of the conversation shares the same facts,” Dorsey said, not “whether those facts are truthful.” At a time when conspiracy theories are gaining traction across social media, it seems naïve to embrace a standard of conversational health that allows for mutual delusion.