The Side of the Road

Two cart drivers approached each other on a wide road. Each could veer left or veer right. It didn’t matter which side they chose, as long as both chose the same.

There was no “correct” side. Left was as good as right. The only wrong answer was disagreement.

After a few collisions, a custom emerged: everyone kept to the left. Not because left was better, but because everyone expected everyone else to keep left. The convention was arbitrary, but once established, deviating from it was dangerous.

Some coordination problems have no natural answer. Any consistent convention works. The challenge is getting everyone onto the same one.