At four-thirty in the afternoon on Monday, February 1, 1960, four college students sat down at the lunch counter at the Woolworth’s in downtown Greensboro, North Carolina. They were freshmen at North Carolina A. & T., a black college a mile or so away.

Social media can’t provide what social change has always required. SEYMOUR CHWAST

“I’d like a cup of coffee, please,” one of the four, Ezell Blair, said to the waitress.

“We don’t serve Negroes here,” she replied.

The Woolworth’s lunch counter was a long L-shaped bar that could seat sixty-six people, with a standup snack bar at one end. The seats were for whites. The snack bar was for blacks. Another employee, a black woman who worked at the steam table, approached the students and tried to warn them away. “You’re acting stupid, ignorant!” she said. They didn’t move. Around five-thirty, the front doors to the store were locked. The four still didn’t move. Finally, they left by a side door. Outside, a small crowd had gathered, including a photographer from the Greensboro Record. “I’ll be back tomorrow with A. & T. College,” one of the students said.

By next morning, the protest had grown to twenty-seven men and four women, most from the same dormitory as the original four. The men were dressed in suits and ties. The students had brought their schoolwork, and studied as they sat at the counter. On Wednesday, students from Greensboro’s “Negro” secondary school, Dudley High, joined in, and the number of protesters swelled to eighty. By Thursday, the protesters numbered three hundred, including three white women, from the Greensboro campus of the University of North Carolina. By Saturday, the sit-in had reached six hundred. People spilled out onto the street. White teen-agers waved Confederate flags. Someone threw a firecracker. At noon, the A. & T. football team arrived. “Here comes the wrecking crew,” one of the white students shouted.

By the following Monday, sit-ins had spread to Winston-Salem, twenty-five miles away, and Durham, fifty miles away. The day after that, students at Fayetteville State Teachers College and at Johnson C. Smith College, in Charlotte, joined in, followed on Wednesday by students at St. Augustine’s College and Shaw University, in Raleigh. On Thursday and Friday, the protest crossed state lines, surfacing in Hampton and Portsmouth, Virginia, in Rock Hill, South Carolina, and in Chattanooga, Tennessee. By the end of the month, there were sit-ins throughout the South, as far west as Texas. “I asked every student I met what the first day of the sitdowns had been like on his campus,” the political theorist Michael Walzer wrote in Dissent. “The answer was always the same: ‘It was like a fever. Everyone wanted to go.’ ” Some seventy thousand students eventually took part. Thousands were arrested and untold thousands more radicalized. These events in the early sixties became a civil-rights war that engulfed the South for the rest of the decade—and it happened without e-mail, texting, Facebook, or Twitter.

The world, we are told, is in the midst of a revolution. The new tools of social media have reinvented social activism. With Facebook and Twitter and the like, the traditional relationship between political authority and popular will has been upended, making it easier for the powerless to collaborate, coördinate, and give voice to their concerns. When ten thousand protesters took to the streets in Moldova in the spring of 2009 to protest against their country’s Communist government, the action was dubbed the Twitter Revolution, because of the means by which the demonstrators had been brought together. A few months after that, when student protests rocked Tehran, the State Department took the unusual step of asking Twitter to suspend scheduled maintenance of its Web site, because the Administration didn’t want such a critical organizing tool out of service at the height of the demonstrations. “Without Twitter the people of Iran would not have felt empowered and confident to stand up for freedom and democracy,” Mark Pfeifle, a former national-security adviser, later wrote, calling for Twitter to be nominated for the Nobel Peace Prize. Where activists were once defined by their causes, they are now defined by their tools. Facebook warriors go online to push for change. “You are the best hope for us all,” James K. Glassman, a former senior State Department official, told a crowd of cyber activists at a recent conference sponsored by Facebook, A. T. & T., Howcast, MTV, and Google. Sites like Facebook, Glassman said, “give the U.S. a significant competitive advantage over terrorists. Some time ago, I said that Al Qaeda was ‘eating our lunch on the Internet.’ That is no longer the case. Al Qaeda is stuck in Web 1.0. The Internet is now about interactivity and conversation.”

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These are strong, and puzzling, claims. Why does it matter who is eating whose lunch on the Internet? Are people who log on to their Facebook page really the best hope for us all? As for Moldova’s so-called Twitter Revolution, Evgeny Morozov, a scholar at Stanford who has been the most persistent of digital evangelism’s critics, points out that Twitter had scant internal significance in Moldova, a country where very few Twitter accounts exist. Nor does it seem to have been a revolution, not least because the protests—as Anne Applebaum suggested in the Washington Post—may well have been a bit of stagecraft cooked up by the government. (In a country paranoid about Romanian revanchism, the protesters flew a Romanian flag over the Parliament building.) In the Iranian case, meanwhile, the people tweeting about the demonstrations were almost all in the West. “It is time to get Twitter’s role in the events in Iran right,” Golnaz Esfandiari wrote, this past summer, in Foreign Policy. “Simply put: There was no Twitter Revolution inside Iran.” The cadre of prominent bloggers, like Andrew Sullivan, who championed the role of social media in Iran, Esfandiari continued, misunderstood the situation. “Western journalists who couldn’t reach—or didn’t bother reaching?—people on the ground in Iran simply scrolled through the English-language tweets post with tag #iranelection,” she wrote. “Through it all, no one seemed to wonder why people trying to coordinate protests in Iran would be writing in any language other than Farsi.”

Some of this grandiosity is to be expected. Innovators tend to be solipsists. They often want to cram every stray fact and experience into their new model. As the historian Robert Darnton has written, “The marvels of communication technology in the present have produced a false consciousness about the past—even a sense that communication has no history, or had nothing of importance to consider before the days of television and the Internet.” But there is something else at work here, in the outsized enthusiasm for social media. Fifty years after one of the most extraordinary episodes of social upheaval in American history, we seem to have forgotten what activism is.

Greensboro in the early nineteen-sixties was the kind of place where racial insubordination was routinely met with violence. The four students who first sat down at the lunch counter were terrified. “I suppose if anyone had come up behind me and yelled ‘Boo,’ I think I would have fallen off my seat,” one of them said later. On the first day, the store manager notified the police chief, who immediately sent two officers to the store. On the third day, a gang of white toughs showed up at the lunch counter and stood ostentatiously behind the protesters, ominously muttering epithets such as “burr-head nigger.” A local Ku Klux Klan leader made an appearance. On Saturday, as tensions grew, someone called in a bomb threat, and the entire store had to be evacuated.

The dangers were even clearer in the Mississippi Freedom Summer Project of 1964, another of the sentinel campaigns of the civil-rights movement. The Student Nonviolent Coordinating Committee recruited hundreds of Northern, largely white unpaid volunteers to run Freedom Schools, register black voters, and raise civil-rights awareness in the Deep South. “No one should go anywhere alone, but certainly not in an automobile and certainly not at night,” they were instructed. Within days of arriving in Mississippi, three volunteers—Michael Schwerner, James Chaney, and Andrew Goodman—were kidnapped and killed, and, during the rest of the summer, thirty-seven black churches were set on fire and dozens of safe houses were bombed; volunteers were beaten, shot at, arrested, and trailed by pickup trucks full of armed men. A quarter of those in the program dropped out. Activism that challenges the status quo—that attacks deeply rooted problems—is not for the faint of heart.

What makes people capable of this kind of activism? The Stanford sociologist Doug McAdam compared the Freedom Summer dropouts with the participants who stayed, and discovered that the key difference wasn’t, as might be expected, ideological fervor. “All of the applicants—participants and withdrawals alike—emerge as highly committed, articulate supporters of the goals and values of the summer program,” he concluded. What mattered more was an applicant’s degree of personal connection to the civil-rights movement. All the volunteers were required to provide a list of personal contacts—the people they wanted kept apprised of their activities—and participants were far more likely than dropouts to have close friends who were also going to Mississippi. High-risk activism, McAdam concluded, is a “strong-tie” phenomenon.

This pattern shows up again and again. One study of the Red Brigades, the Italian terrorist group of the nineteen-seventies, found that seventy per cent of recruits had at least one good friend already in the organization. The same is true of the men who joined the mujahideen in Afghanistan. Even revolutionary actions that look spontaneous, like the demonstrations in East Germany that led to the fall of the Berlin Wall, are, at core, strong-tie phenomena. The opposition movement in East Germany consisted of several hundred groups, each with roughly a dozen members. Each group was in limited contact with the others: at the time, only thirteen per cent of East Germans even had a phone. All they knew was that on Monday nights, outside St. Nicholas Church in downtown Leipzig, people gathered to voice their anger at the state. And the primary determinant of who showed up was “critical friends”—the more friends you had who were critical of the regime the more likely you were to join the protest.

So one crucial fact about the four freshmen at the Greensboro lunch counter—David Richmond, Franklin McCain, Ezell Blair, and Joseph McNeil—was their relationship with one another. McNeil was a roommate of Blair’s in A. & T.’s Scott Hall dormitory. Richmond roomed with McCain one floor up, and Blair, Richmond, and McCain had all gone to Dudley High School. The four would smuggle beer into the dorm and talk late into the night in Blair and McNeil’s room. They would all have remembered the murder of Emmett Till in 1955, the Montgomery bus boycott that same year, and the showdown in Little Rock in 1957. It was McNeil who brought up the idea of a sit-in at Woolworth’s. They’d discussed it for nearly a month. Then McNeil came into the dorm room and asked the others if they were ready. There was a pause, and McCain said, in a way that works only with people who talk late into the night with one another, “Are you guys chicken or not?” Ezell Blair worked up the courage the next day to ask for a cup of coffee because he was flanked by his roommate and two good friends from high school.

The kind of activism associated with social media isn’t like this at all. The platforms of social media are built around weak ties. Twitter is a way of following (or being followed by) people you may never have met. Facebook is a tool for efficiently managing your acquaintances, for keeping up with the people you would not otherwise be able to stay in touch with. That’s why you can have a thousand “friends” on Facebook, as you never could in real life.

This is in many ways a wonderful thing. There is strength in weak ties, as the sociologist Mark Granovetter has observed. Our acquaintances—not our friends—are our greatest source of new ideas and information. The Internet lets us exploit the power of these kinds of distant connections with marvellous efficiency. It’s terrific at the diffusion of innovation, interdisciplinary collaboration, seamlessly matching up buyers and sellers, and the logistical functions of the dating world. But weak ties seldom lead to high-risk activism.

In a new book called “The Dragonfly Effect: Quick, Effective, and Powerful Ways to Use Social Media to Drive Social Change,” the business consultant Andy Smith and the Stanford Business School professor Jennifer Aaker tell the story of Sameer Bhatia, a young Silicon Valley entrepreneur who came down with acute myelogenous leukemia. It’s a perfect illustration of social media’s strengths. Bhatia needed a bone-marrow transplant, but he could not find a match among his relatives and friends. The odds were best with a donor of his ethnicity, and there were few South Asians in the national bone-marrow database. So Bhatia’s business partner sent out an e-mail explaining Bhatia’s plight to more than four hundred of their acquaintances, who forwarded the e-mail to their personal contacts; Facebook pages and YouTube videos were devoted to the Help Sameer campaign. Eventually, nearly twenty-five thousand new people were registered in the bone-marrow database, and Bhatia found a match.

But how did the campaign get so many people to sign up? By not asking too much of them. That’s the only way you can get someone you don’t really know to do something on your behalf. You can get thousands of people to sign up for a donor registry, because doing so is pretty easy. You have to send in a cheek swab and—in the highly unlikely event that your bone marrow is a good match for someone in need—spend a few hours at the hospital. Donating bone marrow isn’t a trivial matter. But it doesn’t involve financial or personal risk; it doesn’t mean spending a summer being chased by armed men in pickup trucks. It doesn’t require that you confront socially entrenched norms and practices. In fact, it’s the kind of commitment that will bring only social acknowledgment and praise.

The evangelists of social media don’t understand this distinction; they seem to believe that a Facebook friend is the same as a real friend and that signing up for a donor registry in Silicon Valley today is activism in the same sense as sitting at a segregated lunch counter in Greensboro in 1960. “Social networks are particularly effective at increasing motivation,” Aaker and Smith write. But that’s not true. Social networks are effective at increasing participation—by lessening the level of motivation that participation requires. The Facebook page of the Save Darfur Coalition has 1,282,339 members, who have donated an average of nine cents apiece. The next biggest Darfur charity on Facebook has 22,073 members, who have donated an average of thirty-five cents. Help Save Darfur has 2,797 members, who have given, on average, fifteen cents. A spokesperson for the Save Darfur Coalition told Newsweek, “We wouldn’t necessarily gauge someone’s value to the advocacy movement based on what they’ve given. This is a powerful mechanism to engage this critical population. They inform their community, attend events, volunteer. It’s not something you can measure by looking at a ledger.” In other words, Facebook activism succeeds not by motivating people to make a real sacrifice but by motivating them to do the things that people do when they are not motivated enough to make a real sacrifice. We are a long way from the lunch counters of Greensboro.

The students who joined the sit-ins across the South during the winter of 1960 described the movement as a “fever.” But the civil-rights movement was more like a military campaign than like a contagion. In the late nineteen-fifties, there had been sixteen sit-ins in various cities throughout the South, fifteen of which were formally organized by civil-rights organizations like the N.A.A.C.P. and CORE. Possible locations for activism were scouted. Plans were drawn up. Movement activists held training sessions and retreats for would-be protesters. The Greensboro Four were a product of this groundwork: all were members of the N.A.A.C.P. Youth Council. They had close ties with the head of the local N.A.A.C.P. chapter. They had been briefed on the earlier wave of sit-ins in Durham, and had been part of a series of movement meetings in activist churches. When the sit-in movement spread from Greensboro throughout the South, it did not spread indiscriminately. It spread to those cities which had preëxisting “movement centers”—a core of dedicated and trained activists ready to turn the “fever” into action.

The civil-rights movement was high-risk activism. It was also, crucially, strategic activism: a challenge to the establishment mounted with precision and discipline. The N.A.A.C.P. was a centralized organization, run from New York according to highly formalized operating procedures. At the Southern Christian Leadership Conference, Martin Luther King, Jr., was the unquestioned authority. At the center of the movement was the black church, which had, as Aldon D. Morris points out in his superb 1984 study, “The Origins of the Civil Rights Movement,” a carefully demarcated division of labor, with various standing committees and disciplined groups. “Each group was task-oriented and coordinated its activities through authority structures,” Morris writes. “Individuals were held accountable for their assigned duties, and important conflicts were resolved by the minister, who usually exercised ultimate authority over the congregation.”

This is the second crucial distinction between traditional activism and its online variant: social media are not about this kind of hierarchical organization. Facebook and the like are tools for building networks, which are the opposite, in structure and character, of hierarchies. Unlike hierarchies, with their rules and procedures, networks aren’t controlled by a single central authority. Decisions are made through consensus, and the ties that bind people to the group are loose.

This structure makes networks enormously resilient and adaptable in low-risk situations. Wikipedia is a perfect example. It doesn’t have an editor, sitting in New York, who directs and corrects each entry. The effort of putting together each entry is self-organized. If every entry in Wikipedia were to be erased tomorrow, the content would swiftly be restored, because that’s what happens when a network of thousands spontaneously devote their time to a task.

There are many things, though, that networks don’t do well. Car companies sensibly use a network to organize their hundreds of suppliers, but not to design their cars. No one believes that the articulation of a coherent design philosophy is best handled by a sprawling, leaderless organizational system. Because networks don’t have a centralized leadership structure and clear lines of authority, they have real difficulty reaching consensus and setting goals. They can’t think strategically; they are chronically prone to conflict and error. How do you make difficult choices about tactics or strategy or philosophical direction when everyone has an equal say?

The Palestine Liberation Organization originated as a network, and the international-relations scholars Mette Eilstrup-Sangiovanni and Calvert Jones argue in a recent essay in International Security that this is why it ran into such trouble as it grew: “Structural features typical of networks—the absence of central authority, the unchecked autonomy of rival groups, and the inability to arbitrate quarrels through formal mechanisms—made the P.L.O. excessively vulnerable to outside manipulation and internal strife.”

In Germany in the nineteen-seventies, they go on, “the far more unified and successful left-wing terrorists tended to organize hierarchically, with professional management and clear divisions of labor. They were concentrated geographically in universities, where they could establish central leadership, trust, and camaraderie through regular, face-to-face meetings.” They seldom betrayed their comrades in arms during police interrogations. Their counterparts on the right were organized as decentralized networks, and had no such discipline. These groups were regularly infiltrated, and members, once arrested, easily gave up their comrades. Similarly, Al Qaeda was most dangerous when it was a unified hierarchy. Now that it has dissipated into a network, it has proved far less effective.

The drawbacks of networks scarcely matter if the network isn’t interested in systemic change—if it just wants to frighten or humiliate or make a splash—or if it doesn’t need to think strategically. But if you’re taking on a powerful and organized establishment you have to be a hierarchy. The Montgomery bus boycott required the participation of tens of thousands of people who depended on public transit to get to and from work each day. It lasted a year. In order to persuade those people to stay true to the cause, the boycott’s organizers tasked each local black church with maintaining morale, and put together a free alternative private carpool service, with forty-eight dispatchers and forty-two pickup stations. Even the White Citizens Council, King later said, conceded that the carpool system moved with “military precision.” By the time King came to Birmingham, for the climactic showdown with Police Commissioner Eugene (Bull) Connor, he had a budget of a million dollars, and a hundred full-time staff members on the ground, divided into operational units. The operation itself was divided into steadily escalating phases, mapped out in advance. Support was maintained through consecutive mass meetings rotating from church to church around the city.