職人の心理状態についてのプラトンの説明については節制の定義と一致させる ことを可能にするような解釈がある。職人はその魂に見合った理知的部分を持っ ているのだから，それは少なくとも以下の程度には働く。実際理知的部分は欲 求的部分に対してこう言う。「見ろ，もしお前の欲望のいくつかを満たすつも りなら，そのすべてを満たすことはできないという事実に直面しなければなら ないだろう。もしみなが欲望のすべてに自由な支配権を与えるとしたらわれわ れのほとんどは死んでしまい，どの欲望も満たせないだろう。それゆえ，他人 も同様にそうすることに同意すると考えて何らかの外的権威に服し，どの欲望 が満たされるべきでどれが満たされるべきでないかについてのその権威の裁定 に従う方がよいのだ。そして哲学者は外的権威として他の誰よりもよい選択で ある。」
もちろんこの議論を読者はすでに聞いている。グラウコンとアデイマントスが たいていの人々が信じていると言う正義の起源についての理論のもう一つの解 釈であり，それは17世紀にトマス・ホッブズが再び主張したものである。けれ どもそれはプラトンが反駁しようとした理論であるから，職人の心理状態と，哲 学者による支配に彼らが自発的に同意するというプラトンの主張を調停しよう とするためにそれを持ち出すのはちょっと都合が悪いに違いない。
その章の始めに注意したように，ホッブズは政治的社会は個人の間の同意，あ るいは社会契約に依存していると論ずる。われわれはいかなる種類の行為が許 されるかについて何らかの同意にいたりか，あるいはそのような裁定をするた めに，特定の人，あるいはグループを任命する。その結果は国家──それはわ れわれの内の一人，あるいは数人，あるいはすべてを含みうる──われわれは それに従うことに同意する。
しかしホッブズのシナリオには別の要素がある。ホッブズによれば，社会契約に署名することによってわれわれが魔法のように変わることはないとわれわれは予め 知っている。われわれはつねにそうであったエゴイストのままであろう。そし て国家を成立させている同意を破棄する機会を与えられれば，もしそれで逃げ 果せると考えるときにはそうするだろう。だからわれわれは国家をその決定を 執行するための物理的強制の手段として認めている。弱い内的抑止の代わりに 外の物理的抑止を立てるのだ。われわれは嵐のような社会関係の中で理性的な 幕間のうちに国家を建設する。そしてなぜわれわれが最初に社会契約をしたかと いうことの理由がもしわれわれを捉えなくなったら，国家によって行使される 剣の力がわれわれを一列に抑えつけるだろう。
明らかにホッブズは社会秩序が自発的同意だけで支えられるというプラトンの 希望を共有していない。職人の魂の理知的部分は一種のホッブズ的な合理性を 働かせることはできるかも知れない。職人は何らかの外的権威に従う必要は理 解できるかも知れない。しかしその同じホッブズ的な合理性が強く示唆するの は，そのような権威が実力に訴えることなしに支配することはできないという ことだ。
プラトンとホッブズの違いの基にあるのは二つの非常に異なった理性の概念で ある。多くの現代の哲学者と同様，ホッブズにとって，理性は純粋に道具的で ある。つまり，それはわれわれに目的や目標を与えるのではなく，その目的に 到達するための手段を与えるだけである。欲望はわれわれが何を欲しているか を告げる。理性はそれをいかに獲得するかの方法を教える。プラトンにとって も理性は道具的機能を持っている。しかしプラトンは理性が実在的な側面も持っ ていると考える。理性がわれわれに告げるのは欲しいものを得るためにどのよ うに取り掛かるべきかということだけでなく，ものの自然本性的な秩序に従っ て生きるべきならば先ず第一に何を欲すべきかをも教える。理性はわれわれに われわれの真の本性にしたがってわれわれが真に何を欲しているかを教えるの である。
ホッブズにとっては，われわれの欲望は生き残ることであり，われわれの理性 は生き残るためには外的権威に従わねばならないと教える。その外的権威その ものに理性的なものは何もない。それがわれわれに生き残ることを認めるのは それが紛争解決のための暴力を持っているからであって，真の本性にしたがっ て何を欲しているかを正しく決定するからではない。プラトンにとってわれわ れの多くが外的権威に従わねばならないのは生き残るためだけでなく，その権 威，哲学者の理性だけがわれわれの真の欲求を教えることができるからである。 けれども職人はそのような理由で哲学者の支配に従うことはありそうもない。 もし従うことで，いくつかの欲望を満たされなくともそれ以外の欲望を満たす ことができるならば，外的権威に従うかも知れない。しかしその権威が彼らの 真の欲望が何であるかを知っていると主張しているから従うというようなこと はしないだろう。
そして読者も従わないだろうという気が私にはする。こうしてわれわれはプラ トンの政治的計画を支えている前提に戻るのである。それをわれわれは以下の 章で探究する。もしプラトンが本当に真なるわれわれの本性についての真実を 実際に知っているとわれわれに確信させ，彼の知っていることを哲学がどのよ うにして知るようにできるのかを示すことができれば，われわれはいつか彼の政 治学への反論を撤回しなければならないだろう。
OF THE NATURALL CONDITION OF MANKIND, AS CONCERNING THEIR FELICITY, AND MISERY
Nature hath made men so equall, in the faculties of body, and mind; as that though there bee found one man sometimes manifestly stronger in body, or of quicker mind then another; yet when all is reckoned together, the difference between man, and man, is not so considerable, as that one man can thereupon claim to himselfe any benefit, to which another may not pretend, as well as he. For as to the strength of body, the weakest has strength enough to kill the strongest, either by secret machination, or by confederacy with others, that are in the same danger with himselfe.
...
Out Of Civil States, There Is Alwayes Warre Of Every One Against Every One Hereby it is manifest, that during the time men live without a common Power to keep them all in awe, they are in that condition which is called Warre; and such a warre, as is of every man, against every man. For WARRE, consisteth not in Battell onely, or the act of fighting; but in a tract of time, wherein the Will to contend by Battell is sufficiently known: and therefore the notion of Time, is to be considered in the nature of Warre; as it is in the nature of Weather. For as the nature of Foule weather, lyeth not in a showre or two of rain; but in an inclination thereto of many dayes together: So the nature of War, consisteth not in actuall fighting; but in the known disposition thereto, during all the time there is no assurance to the contrary. All other time is PEACE.
Sect.4. TO understand political power right, and derive it from its original, we must consider, what state all men are naturally in, and that is, a state of perfect freedom to order their actions, and dispose of their possessions and persons, as they think fit, within the bounds of the law of nature, without asking leave, or depending upon the will of any other man.
A state also of equality, wherein all the power and jurisdiction is reciprocal, no one having more than another; there being nothing more evident, than that creatures of the same species and rank, promiscuously born to all the same advantages of nature, and the use of the same faculties, should also be equal one amongst another without subordination or subjection, unless the lord and master of them all should, by any manifest declaration of his will, set one above another, and confer on him, by an evident and clear appointment, an undoubted right to dominion and sovereignty.
Sec.19. And here we have the plain difference between the state of nature and the state of war, which however some men have confounded, are as far distant, as a state of peace, good will, mutual assistance and preservation, and a state of enmity, malice, violence and mutual destruction, are one from another. Men living together according to reason, without a common superior on earth, with authority to judge between them, is properly the state of nature. But force, or a declared design of force, upon the person of another, where there is no common superior on earth to appeal to for relief, is the state of war: and it is the want of such an appeal gives a man the right of war even against an aggressor, tho' he be in society and a fellow subject.
Thus a thief, whom I cannot harm, but by appeal to the law, for having stolen all that I am worth, I may kill, when he sets on me to rob me but of my horse or coat; because the law, which was made for my preservation, where it cannot interpose to secure my life from present force, which, if lost, is capable of no reparation, permits me my own defence, and the right of war, a liberty to kill the aggressor, because the aggressor allows not time to appeal to our common judge, nor the decision of the law, for remedy in a case where the mischief may be irreparable. Want of a common judge with authority, puts all men in a state of nature: force without right, upon a man's person, makes a state of war, both where there is, and is not, a common judge.
Sec.21. To avoid this state of war (wherein there is no appeal but to heaven, and wherein every the least difference is apt to end, where there is no authority to decide between the contenders) is one great reason of men's putting themselves into society, and quitting the state of nature: for where there is an authority, a power on earth, from which relief can be had by appeal, there the continuance of the state of war is excluded, and the controversy is decided by that power. Had there been any such court, any superior jurisdiction on earth, to determine the right between Jephtha and the Ammonites, they had never come to a state of war: but we see he was forced to appeal to heaven. The Lord the Judge (says he) be judge this day between the children of Israel and the children of Ammon, Judg. xi. 27. and then prosecuting, and relying on his appeal, he leads out his army to battle: and therefore in such controversies, where the question is put, who shall be judge? It cannot be meant, who shall decide the controversy; every one knows what Jephtha here tells us, that the Lord the Judge shall judge. Where there is no judge on earth, the appeal lies to God in heaven. That question then cannot mean, who shall judge, whether another hath put himself in a state of war with me, and whether I may, as Jephtha did, appeal to heaven in it? of that I myself can only be judge in my own conscience, as I will answer it, at the great day, to the supreme judge of all men.
IS THE IDEAL STATE POSSIBLE?
The discussion of the more outrageous proposals brings to the surface, at 471e, the issue that can no longer be postponed: can the ideal state be realized in practice? Opinions differ about this perhaps more violently than about any other issue. The Republic was 'meant by its author not so much as a theoretical treatise, but as a topical manifesto' - Popper, The Open Society and its Enemies, vol i, p. 153. 'These are not so much the machinations of a totalitarian monster as the dreams of an impractical theorist.' - Guthrie, History of Greek Philosophy, vol. iv, p. 469.
Plato does waver on this issue; but that is because the Republic does not have a single aim. It answers the question, whether justice is worth my while; but it also pictures the ideally just state. Doing the latter seems pointless if it is avowedly impracticable; but an ideal of justice is none the worse for being non-realizable in practice if its purpose is to inspire the individual person to be as just as he or she can be. At 472a-e, and right at the end of Book 9, the end of the main argument, Socrates says that it does not matter if the just society is an unattainable ideal, as long as it does serve as an ideal for the just person to try to realize in his or her life. None the less, throughout Books 5 and 6, he argues at length that the just society could come about - cf. 502c: it is hard but not impossible. Evidently he thinks that his political ideal is discredited, whatever its value for personal virtue, if it can be shown to be hopelessly impracticable. Plato wants us to read the Republic not as an enjoyable fantasy, but as something to affect how we live, and for this he has to show that the just city, the society of good people, is not impossible in principle. He does not have to show more than that; it is not, for example, necessary for him to have detailed advice as to how to go about it.
The task is all the same hard, for the just state is not brought about by progressive legal reform, but only by a total change in people's hearts and minds, such as needs a long training to produce. Because Plato downgrades so much the role of institutions in producing a just state, and emphasises exclusively the need for the rulers to have characters of a certain kind, he is in a bind. The just state can only be brought about by just people, but just people are the products only of a just state, such as nowhere actually exists. (This is brought out even more by the insistence that the just ruler must be a philosopher, even though we have yet to see quite how unusual a philosopher would be.)
One reasonable response to this would be gradualism: we, being products of an imperfect state, cannot produce a perfectly just state, but we can try to improve what we have and hand on our reforms to a progressively better educated generation. Plato rejects this move entirely. The just man in a bad society, he thinks, can only save his own soul (496a-497a); he is not called on to improve the lot of others. Plato never argues for this. Presumably he thinks that his reforms are so drastic that tinkering will never produce them, and might produce more harm than good. He rests his hope on breaking into the circle: perhaps somewhere, some time, a just man might arise even in an unjust society (502a-c) and have the power to stop tinkering and start afresh (5ooe-501e), even if this means the desperate step of taking over only the under-tens, to bring them up under an education that will make them just (541a). It is sometimes thought that Plato had in mind, in his picture of the miraculously virtuous tyrant, a particular ruler who decided to become a philosopher, Dionysius II of Syracuse (at least in the very tainted tradition that comes to us in the pseudo-Platonic Letters). But this is highly unlikely, and would spoil the point: Plato has at most to show that the philosopher ruler is possible in principle, not that one will shortly come along. In fact he does not think it likely that any will come along in the foreseeable future, since the truly just and intelligent person is the most likely to be corrupted by society (494a-495b; again Plato is talking about what is likely, and nothing at all is gained by supposing him to have an actual person like Alcibiades in mind, as some romantically suppose).
The more Plato stresses (as he does in Book 6) the philosopher ruler's unique blend of all possible intellectual and moral gifts, developed to their fullest pitch (484-487), the less plausible it is that he or she could exist anywhere but as a result of upbringing in the ideal state. Plato can show only that it is possible in principle, though practically unlikely, to break into the circle. The just state remains more effective as an ideal to stimulate virtue in individuals than as a blueprint for any real society. We find here, unnoticed explicitly by Plato, a divergence between justice in the state and justice in the individual -- a respect in which the uniform account he wants breaks down. For while perfectly just people can exist only in the ideally just state, and the ideally just state can exist only when people are perfectly just, the effect of this is not the same on social and individual justice. Plato seems on the whole reconciled to leaving the just state as an ideal, whereas he wants individuals actually to improve by reading the Republic and using it as an ideal to which to conform themselves. This suggests that while for him justice in the state is an all-or-nothing affair, individual justice is a matter of degree: one can be more or less just, and can improve gradually. In allowing this Plato is making another concession to common sense, which holds that justice, and goodness, in people is a matter of degree. It was left for the Stoics, bolder than Plato, to insist that justice in the person too is an all-or-nothing affair: either you are perfectly just or you are not just at all.
One final important point. The knowledge required in the philosopher ruler, absence of which makes existing states go badly, is practical knowledge. The ruler is like a skilled pilot (488a-489a) or a doctor (489b-c; cf. 382c-d; 389b-d) as opposed to current rulers who are like an animal-keeper who has learned only through experience how to cope with his animal's moods (493a-e). Now a pilot or doctor needs intelligence and rationality, but theirs are practical skills developed in experience. The analogies suggest (plausibly enough) that the rulers will be people with practical wisdom and experience. When we turn to Plato's account of what their knowledge is, we are in for a surprise.