And the remaining one is the Corrective, which arises in voluntary as
well as involuntary transactions. Now this just has a different form
from the aforementioned; for that which is concerned in distribution of
common property is always according to the aforementioned proportion: I
mean that, if the division is made out of common property, the shares
will bear the same proportion to one another as the original
contributions did: and the Unjust which is opposite to this Just is
that which violates the proportionate.
But the Just which arises in transactions between men is an equal in a
certain sense, and the Unjust an unequal, only not in the way of that
proportion but of arithmetical.[12] Because it makes no difference
whether a robbery, for instance, is committed by a good man on a bad or
by a bad man on a good, nor whether a good or a bad man has committed
adultery: the law looks only to the difference created by the injury
and treats the men as previously equal, where the one does and the
other suffers injury, or the one has done and the other suffered harm.
And so this Unjust, being unequal, the judge endeavours to reduce to
equality again, because really when the one party has been wounded and
the other has struck him, or the one kills and the other dies, the
suffering and the doing are divided into unequal shares; well, the
judge tries to restore equality by penalty, thereby taking from the
gain.
For these terms gain and loss are applied to these cases, though
perhaps the term in some particular instance may not be strictly
proper, as gain, for instance, to the man who has given a blow, and
loss to him who has received it: still, when the suffering has been
estimated, the one is called loss and the other gain.
And so the equal is a mean between the more and the less, which
represent gain and loss in contrary ways (I mean, that the more of good
and the less of evil is gain, the less of good and the more of evil is
loss): between which the equal was stated to be a mean, which equal we
say is Just: and so the Corrective Just must be the mean between loss
and gain. And this is the reason why, upon a dispute arising, men have
recourse to the judge: going to the judge is in fact going to the Just,
for the judge is meant to be the personification of the Just.[13] And
men seek a judge as one in the mean, which is expressed in a name given
by some to judges (μεσίδιοι, or middle-men) under the notion that if
they can hit on the mean they shall hit on the Just. The Just is then
surely a mean since the judge is also.
So it is the office of a judge to make things equal, and the line, as
it were, having been unequally divided, he takes from the greater part
that by which it exceeds the half, and adds this on to the less. And
when the whole is divided into two exactly equal portions then men say
they have their own, when they have gotten the equal; and the equal is
a mean between the greater and the less according to arithmetical
equality.
This, by the way, accounts for the etymology of the term by which we in
Greek express the ideas of Just and Judge; (δίκαιον quasi δίχαιον, that
is in two parts, and δικάστης quasi διχάστης, he who divides into two
parts). For when from one of two equal magnitudes somewhat has been
taken and added to the other, this latter exceeds the former by twice
that portion: if it had been merely taken from the former and not added
to the latter, then the latter would have exceeded the former only by
that one portion; but in the other case, the greater exceeds the mean
by one, and the mean exceeds also by one that magnitude from which the
portion was taken. By this illustration, then, we obtain a rule to
determine what one ought to take from him who has the greater, and what
to add to him who has the less. The excess of the mean over the less
must be added to the less, and the excess of the greater over the mean
be taken from the greater.
Thus let there be three straight lines equal to one another. From one
of them cut off a portion, and add as much to another of them. The
whole line thus made will exceed the remainder of the first-named line,
by twice the portion added, and will exceed the untouched line by that
portion.[14] And these terms loss and gain are derived from voluntary
exchange: that is to say, the having more than what was one’s own is
called gaining, and the having less than one’s original stock is called
losing; for instance, in buying or selling, or any other transactions
which are guaranteed by law: but when the result is neither more nor
less, but exactly the same as there was originally,[15] people say they
have their own, and neither lose nor gain.
So then the Just we have been speaking of is a mean between loss and
gain arising in involuntary transactions; that is, it is the having the
same after the transaction as one had before it took place.