To arrive at a conception of justice, it must be established that agreement on the principles is the best method for each person to secure their ends, given their circumstances, knowledge, beliefs, and interests. In justice as fairness, the original position is one in which agreements are fair, parties are equally represented as moral persons, and the outcome is not the result of arbitrary contingencies or the balance of social forces. Justice as fairness employs pure procedural justice from its outset.

The two principles of justice as fairness are preferable if they would be chosen in the original position over every other known alternative. Alternative theories of justice include mixed conceptions of justice, classical teleological conceptions of justice, intuitionistic conceptions of justice, and egoistic conceptions of justice.

The circumstances of justice are the conditions under which cooperation is both permissible and necessary. There are two kinds of circumstances: objective circumstances, which enable and necessitate cooperation; and the condition of moderate scarcity. Society is a cooperative venture for mutual advantage, but it suffers from conflict- and identity-of-interests. A person’s knowledge is incomplete; their powers of reasoning, memory, and attention are limited.