Was either Plato or Aristotle a crusader for social justice?
Plato and Aristotle (or any other ancient Greek) were not pursuing “social justice” in the activist sense. Could they respond, they would claim that justice is justice wherever it is to be found, and injustice is injustice in any context, and to look specifically at “social justice” in the sense of activism would be to miss the point. Aristotle, who wrote after Plato (and was familiar with Plato’s works), is far more systematic in his search for an understanding of justice. Whereas Plato uses dialogue and point-counterpoint argumentation to elucidate the subject, Aristotle approaches systematically, and often employs classification as a technique to aid understanding. Plato, speaking through Socrates, brings up a number of issues that stimulate our thinking on what is just and unjust, but the definition feels incomplete (something Plato indicates through the character of Thrasymachus who interjects that Socrates questions everything, but never gives his own definition)(Republic 336). So while Plato covers some interesting ground in establishing that good is good and bad is bad, it is Aristotle who reasons out how.
Plato and Aristotle were interested in transcendent truth, not the material improvement of one group or class of people relative to another. Socrates would immediately ask what is meant by “social justice” and how it differs from any other type of justice. (I can just imagine the dialogue Socrates would have with a modern leftist activist about truth and justice.) On the other hand, in as much as “social justice” is simply a sub-species of true or absolute justice, both Plato and Aristotle would be strong proponents. Their advocacy might look a bit different than modern activism, since they viewed the contemplative life as being preferable to the political life (Aristotle Ethics Book I Chapter 5). In fact Aristotle seems to anticipate the entire field of social justice in Book 5 of his Ethics. First he inadvertently raises the question whether the lawful is always just (Book 5 Chapter 2) and while he does not directly address the possibility, his definition allows for unjust laws. Then in his definition of one of the two particular forms of justice as proportionate distribution of a common share, and of all justice as being “the proportional” (Book 5 Chapters 2 and 3) he establishes a framework for “social justice” to be the proper, or proportionate distribution of common assets. From the social view, the weakness in Aristotle’s definition is that reasonable people might disagree on what the proper proportion might be in the distribution of common assets among various social groups. Thus his definition can be employed by reformers as well as reactionaries. Put another way, if Aristotle advocates giving each person in society their due (Book 5 Chapter 9) the real problem is agreeing on what is due each person, not on the principle Aristotle has articulated. From this follows the observation that Aristotle has set up a system of analysis for the concept of justice that can be applied by any individual infallibly. A problem arises when people possessing different values apply his system and come to different conclusions. The problem then is not that the system is faulty, but that the value inputs differ. The fact that Aristotle himself believed that there was only one correct set of values – his – does not make his system any less applicable by people holding modern beliefs and values, hence his ongoing relevancy.