When I go to the kinds of places that I go to, I tend to see people I know. Sometimes I don’t know the people I meet in these places, but we find out we have mutual friends or acquiantances. Then we laugh and we say “Small world!”. Small worlds are nice. They make a large and sometimes hostile world seem friendly and controllable. Small worlds mean there is a handle on every person I meet — not a stranger, but a friend-of-a-friend I haven’t met yet. I like being surprised when I walk into a pub in a strange city and meet someone I know from university, or go on demonstration and meet someone I met at a party once. This kind of thing happens so often that it is sometimes really hard to believe that there are six billion individuals on the planet. If that was true, why do I keep bumping into the same five hundred or so?
There answer, of course, is one part our ability to ignore what we aren’t interested in (even people) and another part the ability to move in tremendously limited circles, circumscribed by habit, personality and class. The first factor means that we spend a lot of time not noticing the fifty people in a bar, say, who we don’t know, and far more noticing the one person we do. The second factor means that our choices of location are very very far from random. The shops we use, the evenings we spend, the paths we walk are patterned, always and pervasively, by the kind of person we are. Because of this patterning, we tend to run into a circuit of people who are like us — people with the same or overlapping orbits of habits, preferences and class.
The two factors combine when we manage to ignore our own influence in determining who we meet ‘by chance’. Even in foreign cities our habits, preferences and class will make selections on where we go, allowing us to almost unconsciously ignore certain options (“that restaurant looks tacky”, “that restaurant looks pretentious”, etc) so that when we arrive in a place that we tell ourselves was completely random, we are in fact already set up to bump into other people who are like ourselves, and hence have those small world meetings that we love so much.
The dark side of the small world is when we allow our choices to colour who we meet so strongly that we stop noticing that other kinds of people exist. If we never meet people with other attitudes or backgrounds then we lose a contrast against which we can gauge our own attitudes and background. Suddenly the whole world is full of people just like us (vegans, libertarians, motorist, whatever). From here it is hard to avoid self-righteousness and then irrelevance.