The meaning of justice constitutes the subject matter of this book. It is one of the most important topics discussed in the Nicomachean Ethics for justice was often used by the Greeks in a manner that was practically synonymous with goodness. It will be recalled that in Plato's Republic the theme of the entire book was an attempt to find a satisfactory answer to the question "What is justice?". As the discussion developed it became clear that the subject was a very complicated one. It involved consideration of all that constitutes the good life both for the individual and for the state as a whole. In general it may be said that Aristotle's conception of justice was essentially in harmony with what Plato had taught although his manner of presenting it was more systematic in form and quite devoid of the charm and literary style which Plato had used. There is a further difference, too, in the fact that while Plato was concerned primarily with the meaning of justice in general, Aristotle gives far more attention to its meaning in relation to particular instances.
Using the concepts employed in the field of mathematics Aristotle describes justice in terms of proportion and equality. It is treating individuals with fairness to all and it is a matter of distributing goods in their right proportion. The latter is reminiscent of the doctrine of the golden mean insofar as it means that persons should not be awarded too much or too little. But in another sense justice is unlike the golden mean. It is something for which everyone should strive and no one can ever have too much of it. Justice is both an individual virtue and a social one. It refers to the actions of individuals in their relations with one another and it has to do with forms of government, the making of laws, and the system of rewards and punishment. The discussion of justice especially in relation to matters of state is developed more fully in the Politics and for this reason the major emphasis in the Ethics is given to other aspects of the subject.
