The principle that inequalities are acceptable only if they attach to positions open to all (equal opportunity) and are of benefit to the worst-off members of society. This principle was put forward by John Rawls (1921-2002), and first elaborated in his A Theory of Justice, to capture the requirements of social justice. It would, he asserts, be embraced by rational, prudential individuals asked to provide a standard of justice for their society, in ignorance of (among other things) their place in it. Although Rawls varied the precise formulation of the principles of justice in his later work, the key notion remains that stated above.
— Andrew Reeve




