Justice is an abstract concept
I love chocolates, I love freedom, I love mom, I love my dog, I love April in Paris, etc. When we abstract (disassociate from any instance) we remove the contingent (unpredictable). When I abstract all of this lovin I am left with that which is ‘necessary and sufficient’ I am left with an emotion. When I attach this abstract idea of ‘love’ to these other entities I have a specific instance of an abstract idea.
Is the emotion attached to each one of these abstract ideas exactly the same? I suspect no one knows or can know.
In “A Theory of Justice†John Rawls seeks to discover the essence of the concept ‘justice’. To do this he uses a technique he calls a “veil of ignoranceâ€. To discover the essence of justice one can, while covered by a veil of ignorance, discover what s/he feels ‘in the gut’ just what justice means.
Under the veil of ignorance, like the juror who disregards something said in court at the command of the judge, the individual disregards their station in life to determine what principles they would desire a society to have. ‘Justice is fairness’ is what the rational person chooses to enter if they knew nothing else about that society.
Like the example of abstraction with the concept love so the abstraction of the concept ‘justice’ would yield ‘justice as fairness’.