It doesn't take much
I was walking my toddler to daycare today, as I do most weekdays, and we arrived at a busy intersection nearby. The OX bus to San Francisco had just dropped off a heavily eye-shadowed sullen Goth teenager with dark feathered hair and was preparing to turn the corner on a green light when it just...stopped. Traffic starting backing up several blocks to the bridge to Bay Farm Island.
What was the deal? Why was the bus driver just sitting there? Did she have to stay there until a certain time? Was the bus broken? Were my son and I too close to the curb? I stepped back, then saw the problem.
In the turn lane of the cross street, in the car-sized box of the lane with the giant words KEEP CLEAR painted in it, a woman was sitting in her minivan. Was she oblivious? Stupid? Selfish? Ignorant? Illiterate? Had she just made a mistake?
The KEEP CLEAR was added to the street about a year or so ago because the many busses that make that turn each day were always having trouble managing it without smashing into other vehicles, and snarling traffic. The OX literally could not have made the turn without the clearance afforded by KEEPING CLEAR that spot of the lane.
So in one dumb/oblivious/stubborn/mistaken stroke, this woman had instantly caused a traffic jam at 8:20 AM at a very busy intersection, one that would probably have a ripple effect that would last for an hour.
It doesn't take much to foul up the social system on which our daily lives depend. We don't often stop to recognize this, nor the immediate corollary: that the system is extraordinarily, almost magically, robust and complex.
The irony is that human beings long for the explicable, the comprehensible, to the extent that we rarely even acknowledge the incredible complexity of the systems that flow into our everyday lives, and even deny it outright (viz, Creationism). Yet this complexity is all around us, all the time.