The course investigates the principles of justice involved in the legitimization of the various political regimes. It studies the major theories of social justice, focusing on the principles of contractual justice and of utility, with emphasis given to their critique by the liberal theories of justice and by marxist, feminist and communitarian lines of thought. The course also attempts to highlight the break between the modern and pre-modern conceptions, among which the platonic principle of functional reciprocity, and the aristotelian principle of geometrical equality.