Properly understood, then, the desire to act justly derives in part from the desire to express most fully what we are or can be, namely free and equa… - John Rawls

A conception of justice cannot be deduced from self evident premises or conditions on principles; instead, its justification is a matter of the mutual support of many considerations, of everything fitted together into one coherent view.

First of all, principles should be general. That is, it must be possible to formulate them without use of what would be intuitively recognized as proper names, or rigged definite descriptions.

First of all, no one knows his place in society, his class position or social status; nor does he know his fortune in the distribution of natural assets and abilities, his intelligence and strength, and the like. Nor, again, does anyone know his conception of the good, the particulars of his rational plan of life, or even the special features of psychology such as his aversion to risk or liability to optimism or pessimism. More than this, I assume that the parties do not know the particular circumstances of their own society. That is, they do not know its particular economic or political situation, or the level of civilization and culture it has been able to achieve. The persons in the original position have no information as to which generation they belong.