This question was discussed by the historical Sokrates, Memorabilia of Xenophon.
That the definition of νόμος or Law was discussed by Sokrates, we know, not only from the general description of his debates given in Xenophon, but also from the interesting description (in that author) of the conversation between the youthful Alkibiades and Perikles.[34] The interrogations employed by Alkibiades on that occasion are Sokratic, and must have been derived, directly or indirectly, from Sokrates. They are partially analogous to the questions of Sokrates in the dialogue Minos, and they end by driving Perikles into a confusion, left unexplained, between Law and Lawlessness.
[34] Xen. Mem. i. 1, 16; i. 2, 42-46.
Definitions of law — suggested and refuted. Law includes, as a portion of its meaning, justice, goodness, usefulness, &c. Bad decrees are not laws.
Definitions of νόμος are here given by the Companion, who undergoes a cross-examination upon them. First, he says, that Νόμος = τὰ νομιζόμενα. But this is rejected by Sokrates, who intimates that Law is not the aggregate of laws enacted or of customs held binding: but that which lies behind these laws and customs, imparting to them their binding force.[35] We are to enquire what this is. The Companion declares that it is the public decree of the city: political or social opinion. But this again Sokrates contests: putting questions to show that Law includes, as a portion of its meaning, justice, goodness, beauty, and preservation of the city with its possessions; while lawlessness includes injustice, evil, ugliness, and destruction. There can be no such thing as bad or wicked law.[36] But among decrees of the city, some are bad, some are good. Therefore to define Law as a decree of the city, thus generally, is incorrect. It is only the good decree, not the bad decree, which is Law. Now the good decree or opinion, is the true opinion: that is, it is the finding out of reality. Law therefore wishes or aims to be the finding out of reality: and if there are differences between different nations, this is because the power to find out does not always accompany the wish to find out.
[35] Plato, Minos, 314 A. ἐπειδὴ νόμῳ τὰ νομιζόμενα νομίζεται, τίνι ὄντι τῷ νόμῳ νομίζεται;
[36] Plato, Minos, 314 E. καὶ μὴν νόμος γε οὐκ ἦν πονηρός.
Sokrates affirms that law is everywhere the same — it is the declared judgment and command of the Wise man upon the subject to which it refers — it is truth and reality, found out and certified by him.
As to the assertion — that Law is one thing here, another thing there, one thing at one time, another thing at another — Sokrates contests it. Just things are just (he says) everywhere and at all times; unjust things are unjust also. Heavy things are heavy, light things light, at one time, as well as at another. So also honourable things are everywhere honourable, base things everywhere base. In general phrase, existent things are everywhere existent,[37] non-existent things are not existent. Whoever therefore fails to attain the existent and real, fails to attain the lawful and just. It is only the man of art and knowledge, in this or that department, who attains the existent, the real, the right, true, lawful, just. Thus the authoritative rescripts or laws in matters of medicine, are those laid down by practitioners who know that subject, all of whom agree in what they lay down: the laws of cookery, the laws of agriculture and of gardening — are rescripts delivered by artists who know respectively each of those subjects. So also about Just and Unjust, about the political and social arrangements of the city — the authoritative rescripts or laws are, those laid down by the artists or men of knowledge in that department, all of whom agree in laying down the same: that is, all the men of art called kings or lawgivers. It is only the right, the true, the real — that which these artists attain — which is properly a law and is entitled to be so called. That which is not right is not a law, — ought not to be so called — and is only supposed to be a law by the error of ignorant men.[38]
[37] M. Boeckh remarks justly in his note on this passage — “neque enim illud demonstratum est, eadem omnibus legitima esse — sed tantum, notionem” (rather the sentiment or emotion) “legitimi omnibus eandem esse. Sed omnia scriptor hic confundit.”