Nicomachean Ethics

The remaining one species is the corrective, which occurs in transactions, both voluntary and involuntary. This just has a different form from the previous one. For the distributive just of common funds is always according to the aforementioned proportion; indeed, even if a distribution is made from common assets, it will be according to the same ratio which the contributions have to one another. And the unjust opposed to this just is what is contrary to the proportion. But the just in transactions is indeed something equal, and the unjust is unequal, but not according to that proportion, but according to the arithmetical one. For it makes no difference whether a good man has defrauded a bad man, or a bad man a good one, nor whether a good man or a bad man has committed adultery; rather, the law looks only to the difference of the injury, and treats them as equals, if one acts unjustly and the other is treated unjustly, and if one has damaged and the other is damaged. Therefore, since this unjust is unequal, the judge tries to equalize it; for even when one has been struck and the other has struck, or one has killed and the other is dead, the suffering and the action are divided into unequal parts; but he tries by means of the penalty to equalize them, taking away from the gain. For the term “gain” is used, to speak generally, in such cases, even if for some of them it is not the proper word, as for instance for the one who struck, and “loss” for the one who suffered; but when the suffering is measured, one is called loss and the other gain. Therefore, the equal is the mean between the more and the less, and gain and loss are respectively more and less in opposite ways (more of good and less of evil being gain, and the contrary loss); and the mean between them was the equal, which we say is just; so that the corrective just would be the mean between loss and gain. Therefore, when people dispute, they flee to the judge; and to go to the judge is to go to the just; for the judge wishes to be as it were a living justice; and they seek a judge who is a mean, and some call them mediators, as if, if they obtain the mean, they will obtain the just. Therefore, the just is a certain mean, since the judge indeed is so. And the judge equalizes, and just as if a line had been cut into unequal parts, from that which the greater segment exceeds the half, he takes this away and adds it to the smaller segment. And when the whole has been divided in two, then people say they have their own when they get the equal. And the equal is the mean between the greater and the smaller according to arithmetical proportion. For this reason too it is called “just” (dikaion), because it is in two parts (dicha), as if one were to say “two-parted” (dichaion), and the judge (dikastes) is a halver (dichastes). For when from one of two equals something is taken away, and is added to the other, the latter exceeds the former by these two; for if it had been taken away indeed, but not added, it would have exceeded by one only. It exceeds the mean, therefore, by one, and the mean exceeds that from which it was taken by one. By this, then, we shall know both what we ought to take away from him who has more, and what to add to him who has less; for by as much as the mean exceeds, this we must add to him who has less, and by as much as it is exceeded, we must take away from the greatest. Let the lines aa, ββ, γγ be equal to one another; from aa let ae be taken away, and to γγ let γδ be added, so that the whole δγγ exceeds εα by γδ and γζ; therefore it exceeds ββ by γδ. And these names, loss and gain, have come from voluntary exchange; for to have more than one’s own is called gaining, and to have less than what one had at the beginning is to lose, as in buying and selling, and in all other transactions where the law has given security. But when they get neither more nor less but the very things that come from themselves, they say they have their own and are neither losing nor gaining. Therefore, the just is a certain mean of gain and loss in transactions contrary to the voluntary, namely, to have the equal both before and after.