 Property is a general term for rules governing access to and control of land and other material resources. Because these rules are disputed, both in regard to their general shape and in regard to their particular application, there are interesting philosophical issues about the justification of property. Modern philosophical discussions focus mostly on the issue of the justification of private property rights (as opposed to common or collective property). ‘Private property’ refers to a kind of system that allocates particular objects like pieces of land to particular individuals to use and manage as they please, to the exclusion of others (even others who have a greater need for the resources) and to the exclusion also of any detailed control by society. Though these exclusions make the idea of private property seem problematic, philosophers have often argued that it is necessary for the ethical development of the individual, or for the creation of a social environment in which people can prosper as free and responsible agents.