Predictably Irrational: The Hidden Forces That Shape Our Decisions

by Dan Ariely

A good analogy for social distrust can be found in the “tragedy of the commons.” This phrase can be traced back to Oxford professor William Forster Lloyd, who described the phenomenon in his 1833 book on population. He noted that in medieval England, parishes had common land on which each member of the community could graze a limited number of cattle and sheep.* Keeping the number of animals low allowed the grass to grow back at a speed that kept its level more or less the same. This approach was rather successful when all the farmers stuck to the rule. Unfortunately, in their selfish desire to improve their own financial situations, some of the farmers increased the number of their animals to a level that the land could not sustain. This strategy was very good (at least in the short run) for the individual farmers who had more animals, but each additional cow or sheep resulted in less grass for all of the animals. As the grass dwindled, all the livestock on the commons became malnourished and underproductive—a result that hurt everyone, including the greedy farmers.