 Among the general facts the parties know are “the circumstances of justice.” Rawls says these are “conditions under which human cooperation is both possible and necessary” (TJ 126/109 rev.). Following Hume, Rawls distinguishes two general kinds: the objective and subjective circumstances of justice. The former include physical facts about human beings, such as their rough similarity in mental and physical faculties, and vulnerability to the united force of others. Objective circumstances also include conditions of moderate scarcity of resources: there are not enough resources to satisfy everyone’s demands, but there are enough to provide all with adequate satisfaction of their basic needs; unlike conditions of extreme scarcity (e.g. famine) cooperation then seems productive and worthwhile for people.