Kleinfeld assumed that Milgram’s study must have been replicated for his results to have been so widely and enthusiastically accepted. Confirming the validity of a finding by repeating experiments is, after all, a hallmark of the scientific process. Kleinfeld scoured the academic literature but found only two follow-up studies, one done by Milgram himself. And neither one, Kleinfeld says, substantiated the six-degrees claim. “I was disappointed in Milgram, who was one of my idols, for avoiding the limitations of his research in the arresting and well-written article he had published in Psychology Today,” Kleinfeld says. “My students, however, were not surprised. The results supported their notions of the limitations of social research.”
Was Milgram so in love with the idea of six degrees that he overlooked the weak statistics.
Milgram had said that he got the idea for his small world study from social scientist Ithiel de Sola Pool and mathematician Manfred Kochen, who, in the 1950s, spent a good deal of time trying to arrive at a mathematical formula that would explain how closely all of us are actually connected. But de Sola Pool and Kochen were unable to find an equation that satisfactorily represented the nuances and complexities of society. Milgram, who was already famous for the obedience experiment in which study subjects administered painful electric shocks to other study subjects when urged to do so by an authority figure, came up with the letter method as a tool to try to solve the problem in real life.
Usually scientists publish in academic journals first, and then bring their results to the lay press. Milgram did it in reverse by publishing first in Psychology Today. “This allowed Milgram to sidestep the usual publication lag in academic publishing,” explains Thomas Blass, a professor of psychology at the University of Maryland and author of The Man Who Shocked the World: The Life and Legacy of Stanley Milgram. But in writing for the lay public, Milgram omitted statistics—the numbers that would show how few of his chains were in fact completed. Milgram did publish the actual results of his second study, including the statistics, in an academic journal a couple of years later, pondering at length the reasons for the low completion rates of the chains.
Kleinfeld’s interpretation of all this—which she also published in Psychology Today (March/April 2002)—is that Milgram was so in love with the idea of six degrees that he overlooked the weak statistics backing it up. And worse, he promoted his sketchy results to an unsuspecting public. Not that she thinks the public minds. In talking to others about their coincidental experiences running into friends and friends of friends in unlikely places, she’s become convinced that the idea of six degrees has deep psychological appeal. “The belief in a small world gives people a sense of security,” she says.
But that’s not really the end of the story. In the interval between Milgram’s work and Kleinfeld’s digging through those boxes, a field known as the science of networks had blossomed. “Just about anything in the social, biological, and physical world has to do with systems that comprise lots and lots of interacting components,” says Duncan Watts, a professor of sociology at Columbia University. It’s important to understand how networks function because, as Watts puts it, “that has relevance to just about every question we’re interested in, whether we’re talking about the spread of epidemics, or changes in social norms, or fashions, or the expression of the genome.” It’s all about some sort of process driven by many things interacting with one another. “And the interactions,” Watts believes, “are critical.”
Professor Duncan Watts
Image courtesy of Myrna Suárez/Twin b Photography
In 1998 Watts and Steven Strogatz, a professor of applied mathematics at Cornell University, published a paper in Nature that did what de Sola Pool and Kochen hadn’t done: It provided a mathematical explanation for how random people living far apart can be linked by a handful of connections. The concept rests upon the idea that we all lead multidimensional lives. “People organize their lives along different social dimensions,” explains Watts. “I know some people because of what I do for work, some because of where I live, and others because of where I grew up. A professional colleague and someone I grew up with may look at one another and not think they have anything in common, but I form the bridge because I’m close to each one of them.”
It’s these acquaintances that allow us to cut through the swaths of humanity, and many social dimensions, to reach people who seem far removed from ourselves. But what of the enormous attrition rate in Milgram’s study, which Kleinfeld found so damning? Milgram, in the results he published in the scientific literature, speculated that study participants hadn’t completed their chains because they lacked motivation or didn’t really believe that they could reach their targets. Watts tends to agree with that argument—largely because he’s seen it in action.
