A Theory of Justice is a work of political philosophy and ethics by John Rawls, in which Rawls attempts to solve the problem of distributive justice (the socially just distribution of goods in a society) by utilising a variant of the familiar device of the social contract. The resultant theory is known as "Justice as Fairness", from which Rawls derives his two principles of justice: the liberty principle and the difference principle. First published in 1971, A Theory of Justice was revised in both 1975 (for the translated editions) and 1999.