Rational Choice with Deontic Constraints

Abstract

Anyone who has ever lived with roommates understands the Hobbesian state of nature implicitly. People sharing accommodations quickly discover that buying groceries, doing the dishes, sweeping the floor, and a thousand other household tasks, are all prisoner's dilemmas waiting to happen. For instance, if food is purchased communally, it gives everyone an incentive to overconsume (because the majority of the cost of anything anyone eats is borne by the others). Individuals also have an incentive to buy expensive items that the others are unlikely to want. As a result, everyone's food bill will be higher than it would be if everyone did their own shopping. Things are not much better when it comes to other aspects of household organization. Cleaning is a common sticking point. Once there are a certain number of people living in a house, cleanliness becomes a quasi-public good. If everyone ‘pitched in’ to clean up, then everyone would be happier. But there is a free-rider incentive—before cleaning, it's best to wait around a bit to see if someone else will do it. As a result, the dishes will stack up in the sink, the carpet will get grungy, and so on.