Book 5

In regard to Justice²⁶⁶ and Injustice, we have to enquire what sort of actions precisely they are concerned with, in what sense Justice is the observance of a mean, and what are the extremes between which that which is just is a mean.

Ch. 1 [sect. 2] Our enquiry may follow the same procedure as our preceding investigations.

Ch. 1 [sect. 3]

Now we observe that everybody means by Justice that moral disposition which renders men apt to do just things, and which causes them to act justly and to wish what is just; and similarly by Injustice that disposition which makes men act unjustly and wish what is unjust. Let us then assume this definition to start with as broadly correct.

Ch. 1 [sect. 4]

The fact is that it is not the same with dispositions as with sciences and faculties. It seems that the same faculty or science deals with opposite things²⁶⁷ ; but a disposition or condition which produces a certain result does not also produce the opposite results; for example, health does not give rise to unhealthy actions, but only to healthy ones: healthy walking means walking as a healthy man would walk.²⁶⁸

Ch. 1 [sect. 5]

Hence²⁶⁹ sometimes the nature of one of two opposite dispositions is inferred from the other, sometimes dispositions are known from the things in which they are found; for instance, if we know what good bodily condition is,
[20] we know from this what bad condition is as well, but we also know what good condition is from bodies in good condition, and know what bodies are in good condition from knowing what good condition is. Thus, supposing good condition is firmness of flesh, bad condition must be flabbiness of flesh, and a diet productive of good condition²⁷⁰ must be a diet producing firmness of flesh.

Ch. 1 [sect. 6]

Also, if one of two correlative groups of words is used in several senses, it follows as a rule that the other is used in several senses too: for example, if just has more than one meaning, so also has unjust and Injustice.

Ch. 1 [sect. 7] Now it appears that the terms Justice and Injustice are used in several senses, but as the equivocal uses are closely connected, the equivocation is not detected; whereas in the case of widely different things called by a common name, the equivocation is comparatively obvious: for example the difference being considerable when it is one of external form, the equivocal use of the word kleis key to denote both the bone²⁷¹ at the base of the neck and the instrument with which we lock our doors.

Ch. 1 [sect. 8]

Let us then ascertain in how many senses a man is said to be unjust. Now the term unjust is held to apply both to the man who breaks the law and the man who takes more than his due, the unfair²⁷² man. Hence it is clear that the law-abiding man and the fair man will both be just. The just therefore means that which is lawful and that which is equal or fair, and the unjust means that which is illegal and that which is unequal or unfair. [p. 1129b]