Anyway, I'm picking this series back up.
Small Worlds networks mean that people don't simply connect at random. They connect in clusters, ensuring that they interact with the same people frequently, even in large networks. This in turn reduces the Prisoners' Dilemma and helps create social capital.So what is the Prisonsers' Dilemma? Aside from being the bane of the existence of anyone who ever did graduate school in the social sciences (like yours truly)? It's the basis of game theory, and it elucidates why people tend not to cooperate, even though it would be in both their best interests to do so.
Shirky, chapter 9, page 222
In a nutshell, there are three possible outcomes: both people cooperate, both betray trust, or one cooperates while the other betrays trust. Even though the game is set up so that the optimal total outcome eventuates if both people cooperate, the incentive to betray trust and screw the other person while benefiting yourself is so strong that both people are inclined to betray trust, which leads to both being punished.
So what does this all mean? Basically, humans are not inclined to trust strangers. And with good reason - you don't know them, and they could be bad people who are out to hurt you ("I don't know Mary. Mary could be an axe murderer. No way am I trusting Mary."). However, having a mutual tie, even if it's a relatively weak tie, helps us take the first step to trusting each other, which leads to building trust, which can produce great outcomes as we cooperate and work together ("I don't know Mary. But my colleague Sue knows Mary. I know Sue wouldn't be friends with an axe murderer. Therefore, I feel confident that I can meet Mary for coffee without risking life and limb.")
Weak ties are often derided, but they are in fact the foundation of social networks. Where can your weak ties take you? Who have you taken a risk on trusting because of a network connection? What good as come about as a result of that cooperation?