 The most common form of justificatory argument is consequentialist: people in general are better off when a given class of resources is governed by a private property regime than by any alternative system. Under private property, it is said, the resources will be more wisely used, or used to satisfy a wider (and perhaps more varied) set of wants than under any alternative system, so that the overall enjoyment that humans derive from a given stock of resources will be increased. The most persuasive argument of this kind is sometimes referred to as ‘the tragedy of the commons’ (Hardin 1968). If everyone is entitled to use a given piece of land, then no one has an incentive to see that crops are planted or that the land is not over-used. Or if anyone does take on this responsibility, they themselves are likely to bear all the costs of doing so (the costs of planting or the costs of their own self-restraint), while any benefits of their prudence will accrue to all subsequent users. And in many cases there will be no benefits, since one individual’s planning or restraint will be futile unless others cooperate. So, under a system of common property, each commoner has an incentive to get as much as possible from the land as quickly as possible, since the benefits of doing this are in the short-term concentrated and assured, while the long-term benefits of self-restraint are uncertain and diffused. However, if a piece of hitherto common land is divided into parcels and each parcel is assigned to a particular individual who can control what happens there, then planning and self-restraint will have an opportunity to assert themselves. For now the person who bears the cost of restraint is in a position to reap all the benefits; so that if people are rational and if restraint (or some other form of forward-looking activity) is in fact cost-effective, there will be an overall increase in the amount of utility derived.