...Yet just which network model describes human society remains a subject of fierce debate. Mr. Barabasi [Linked] believes the human social network is scale-free with the expected smattering of richly connected hubs. Mr. Watts disagrees. "If you asked people to list the number of people they recognize, that could be scale-free, everyone recognizes Michael Jordan," he said. "But if you said, `Who would you trust to look after your kids?' That's not scale-free. As you start to ratchet up the requirements for what it means to know someone, connections diminish."
From "Six Degrees" (W. W. Norton)
A network cluster in which Ego has six friends, each of whom is friends with at least one other.
Is society a small-world network of the sort Milgram was interested in? Mr. Watts spent the past year trying to test that idea, using the Internet as a proxy for the world population. Whatever the results, he says, it's clear that human psychology has not yet adapted to the implications of a connected world.
"We like to think of our world as full of atomized individuals," he said. "But decisions people make and the actions they take are so hopelessly entwined with the behaviors of everyone else that it's difficult to draw the boundaries around the individual." When it comes to choosing a CD or explaining the success of Harry Potter, your preference may matter less than the network's.
But some scholars dismiss the network hypothesis altogether. Judith S. Kleinfeld, a psychologist at the University of Alaska at Fairbanks, prompted a flurry of media attention last year when she published an article questioning the validity of Milgram's small-world findings. Given the prevalence of networks — from power grids to airports to the Internet — it's tempting to assume that human society is a network as well, she says. But ultimately, that is impossible to prove.
"Duncan assumes the world is a matrix," Ms. Kleinfeld said in a telephone interview. "He wants to know how you get from one point on it to another. But what if the world isn't a matrix? What if people aren't all connected? What if they're islands in space?" ...
