Cooperation between strangers can only evolve if the cost of altruistic punishment is low and its impact on free riders is high. This is the result of a web based Dutch experiment with more than eight hundred participants where the cost of altruistic punishment and the impact on free riders have been varied, using real money in a public game.
It came out that the decision whether to punish free riders or not depends on a mix of emotion and cost to impact calculation. On the emotional side, a free rider provokes negative feelings in cooperative subjects. But before the subjects take action, they calculate the cost to impact ratio of the punishment. Cooperation only occurs if the level of free riding that goes unpunished is relatively low, and this in turn depends on a favourable cost to impact ratio.
Altruistic punishment costs the punisher some amount of effort, for instance time, emotional or physical energy, a risk of being attacked, maybe even money, without any direct personal benefit. The benefit is only indirect, serving the group as a whole. And this group typically is a group of strangers, only united by concordant interests.
Altruistic punishment can only lead to cooperation if reputation and reciprocity are important in the group of strangers, and if it is easily possible to opt out, that is, not to participate in any activity of the group.
The case of science, quacks, and skeptics
The success of science in modern world has prompted quacks to use pseudo science as a vehicle of free riding, and unfortunately they sometimes even manage to act against the only viable countermeasure, altruistic punishment. Skeptics play an important role in keeping up a high quality science by cooperation of all those who really use their brains, unmasking pseudo science, calling quacks quacks and exposing their fraudulent tricks in public. Even at the risk of lawsuits.
There has been a sad day recently when a self-appointed "professor" and leader of an "institute", Joseph Chikelue Obi, has managed to silence our skeptic colleague Le Canard Noir at Quackometer Blog. After having threatened the web service provider of Quackometer with a million pound lawsuit, Obi has won the first round of the game: Le Canard Noir has been forced to take down his critical remarks.
But there is a second round, fortunately. Many bloggers of the skeptical community have reposted the article that has been deleted from Quackometer, the first copy I have found is at Steven Novella's Neurologica Blog, and also Orac has reposted, and more than thirty others. It's worth following these links.
So, at last, I hope to gain back my confidence that altruistic punishment of quacks is still working.