Whether the Mean Is to Be Observed in the Same Way in Distributive As
in Commutative Justice?
Objection 1: It would seem that the mean in distributive justice is
to be observed in the same way as in commutative justice. For each of
these is a kind of particular justice, as stated above (A. 1). Now
the mean is taken in the same way in all the parts of temperance or
fortitude. Therefore the mean should also be observed in the same way
in both distributive and commutative justice.
Obj. 2: Further, the form of a moral virtue consists in observing the
mean which is determined in accordance with reason. Since, then, one
virtue has one form, it seems that the mean for both should be the
same.
Obj. 3: Further, in order to observe the mean in distributive justice
we have to consider the various deserts of persons. Now a person's
deserts are considered also in commutative justice, for instance, in
punishments; thus a man who strikes a prince is punished more than
one who strikes a private individual. Therefore the mean is observed
in the same way in both kinds of justice.
_On the contrary,_ The Philosopher says (Ethic. v, 3, 4) that the
mean in distributive justice is observed according to "geometrical
proportion," whereas in commutative justice it follows "arithmetical
proportion."
_I answer that,_ As stated above (A. 1), in distributive justice
something is given to a private individual, in so far as what belongs
to the whole is due to the part, and in a quantity that is
proportionate to the importance of the position of that part in
respect of the whole. Consequently in distributive justice a person
receives all the more of the common goods, according as he holds a
more prominent position in the community. This prominence in an
aristocratic community is gauged according to virtue, in an oligarchy
according to wealth, in a democracy according to liberty, and in
various ways according to various forms of community. Hence in
distributive justice the mean is observed, not according to equality
between thing and thing, but according to proportion between things
and persons: in such a way that even as one person surpasses another,
so that which is given to one person surpasses that which is allotted
to another. Hence the Philosopher says (Ethic. v, 3, 4) that the mean
in the latter case follows "geometrical proportion," wherein equality
depends not on quantity but on proportion. For example we say that 6
is to 4 as 3 is to 2, because in either case the proportion equals
1½; since the greater number is the sum of the lesser plus its half:
whereas the equality of excess is not one of quantity, because 6
exceeds 4 by 2, while 3 exceeds 2 by 1.
On the other hand in commutations something is paid to an individual
on account of something of his that has been received, as may be seen
chiefly in selling and buying, where the notion of commutation is
found primarily. Hence it is necessary to equalize thing with thing,
so that the one person should pay back to the other just so much as
he has become richer out of that which belonged to the other. The
result of this will be equality according to the "arithmetical mean"
which is gauged according to equal excess in quantity. Thus 5 is the
mean between 6 and 4, since it exceeds the latter and is exceeded by
the former, by 1. Accordingly if, at the start, both persons have 5,
and one of them receives 1 out of the other's belongings, the one
that is the receiver, will have 6, and the other will be left with 4:
and so there will be justice if both be brought back to the mean, 1
being taken from him that has 6, and given to him that has 4, for
then both will have 5 which is the mean.
Reply Obj. 1: In the other moral virtues the rational, not the real
mean, is to be followed: but justice follows the real mean; wherefore
the mean, in justice, depends on the diversity of things.
Reply Obj. 2: Equality is the general form of justice, wherein
distributive and commutative justice agree: but in one we find
equality of geometrical proportion, whereas in the other we find
equality of arithmetical proportion.
Reply Obj. 3: In actions and passions a person's station affects the
quantity of a thing: for it is a greater injury to strike a prince
than a private person. Hence in distributive justice a person's
station is considered in itself, whereas in commutative justice it is
considered in so far as it causes a diversity of things.
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