The same argument is employed by Sokrates in the Gorgias, p. 476 E.
All unjust men are unjust involuntarily. — No such thing as voluntary injustice. Injustice depends upon the temper of the agent — Distinction between damage and injury.
But Plato differs from the public on another point also. He affirms all wicked or unjust men to be unwillingly wicked or unjust: he affirms that no man does injustice willingly.[295] How is he to carry out this maxim in his laws? He cannot make any distinction (as all existing cities make it) in the penalties prescribed for voluntary injustice, and for involuntary injustice; for he does not recognise the former as real.[296] He must explain upon what foundation his dissent from the public rests. He discriminates between Damnum and Injuria — between Damage or Hurt, and Injustice. When damage is done, it is sometimes done voluntarily — sometimes, and quite as often, involuntarily. The public call this latter by the name of involuntary injustice; but in Plato’s view it is no injustice at all. Injustice is essentially distinct from damage: it depends on the temper, purpose, or disposition of the agent, not on the result as affecting the patient. A man may be unjust when he is conferring benefit upon another, as well as when he is doing hurt to another. Whether the result be beneficial or hurtful, the action will be right or wrong, and the agent just or unjust, according to the condition of his own mind in doing it.[297]
[295] Plato, Legg. ix. p. 860 D-E.
[296] Plato, Legg. ix. p. 861 B. ἃ δὴ κατὰ πάσας τὰς πόλεις ὑπὸ νομοθετῶν πάντων τῶν πώποτε γενομένων ὡς δύο εἴδη τῶν ἀδικημάτων ὄντα, τὰ μὲν ἑκούσια, τὰ δὲ ἀκούσια, ταύτῃ καὶ νομοθετεῖται.
The eighth chapter, fifth Book, of Aristotle’s Nikomachean Ethics, discusses this question more instructively than Plato.
[297] Plato, Legg. ix. pp. 861-862.
Damage may be voluntary or involuntary — Injustice is shown often by conferring corrupt profit upon another — Purpose of punishment, to heal the distemper of the criminal.
The real distinction therefore (according to Plato) is not between voluntary and involuntary injustice, but between voluntary and involuntary damage. Voluntary damage is injustice, but it is not voluntary injustice. The unjust agent, so far forth as unjust, acts involuntarily: he is under the perverting influence of mental distemper. He must be compelled to make good the damage which he has done, or to offer such requital as may satisfy the feelings of the person damaged: and he must besides be subjected to such treatment as will heal the distemper of his mind, so that he will not be disposed to do farther voluntary damage in future. And he ought to be subjected to this treatment equally, whether his mental distemper (injustice) has shown itself in doing wilful damage to another, or in conferring corrupt profit on another — in taking away another man’s property, or in giving away his own property wrongfully.[298] The healing treatment may be different in different cases: discourses addressed, or works imposed — pleasures or pains, honour or disgrace, fine or otherwise. But in all cases the purpose is one and the same — to heal the distemper of his mind, and to make him hate injustice. If he be found incurable, he must be put to death. It is a gain for himself to die, and a still greater gain for society that he should die, since his execution will serve as a warning to others.[299]
[298] Plato, Legg. ix. p. 862 B. οὔτ’ εἴ τίς τῳ δίδωσί τι τῶν ὄντων οὔτ’ εἰ τοὐναντίον ἀφαιρεῖται, δίκαιον ἁπλῶς ἢ ἄδικον χρὴ τὸ τοιοῦτον οὕτω λέγειν, ἀλλ’ ἐὰν ἤθει καὶ δικαίῳ τρόπῳ χρώμενός τις ὠφελῇ τινά τι καὶ βλάπτῃ, τοῦτό ἐστι τῷ νομοθέτῃ θεατέον, καὶ πρὸς δύο ταῦτα δὴ βλεπτέον, πρός τε ἀδικίαν καὶ βλαβήν.