In his Republic, Plato sets forth a vision of a Just City that he considers to be radical and unlikely to occur. This is because his plan includes elements such as the equality of women, the abolition of the family, the disregard for the happiness of the rulers, and the institution of the philosopher-kings. Despite these difficulties, Plato always maintains that the just city is, in principle, possible.
The first goal in the establishment of the Just City is the equality of women. Plato agrees that “the natures of man and woman are different,” but he goes on to say, “The only difference appears to be that the male begets and the female brings forth.” Because Plato believes that the physical world is not real compared to his Realm of the Forms, he sees this difference as merely superficial and irrelevant to their place in the Just City. For this reason, Plato concludes that women as well as men should be allowed to be Guardians of the city. However just this may seem, Plato notes that the plan “might be ridiculed as involving a good many breaches of custom.” Nonetheless, he asserts that “we must not be frightened of the many witticisms that might be aimed at such a revolution.” He is saying that although the equality of women will be difficult to establish, it can and ought to be done.
Another element in the plan is the abolition of the family among the Guardians. Plato makes it clear that the Just City must find a way of aligning the interests of the Guardians with the interests of the regular citizens. Only when this is done will the Guardians genuinely desire the good of the regular citizens. But, parents inevitably value their own children’s good over the good of the city in which they live. Therefore, “wives are to be held in common by all; so too are the children, and no parent is to know his own child, nor any child his parent.” Plato is well aware that this will not be done easily. He says, “I should expect dispute to arise chiefly over the question whether it is possible.” He claims that it is indeed possible, because the Rulers, in making the law and being virtuous, will follow the law themselves, and the Auxiliaries, being good Auxiliaries, will obey any command the Rulers give them.
Another difficulty is initially pointed out in the dialogue by Adeimantus. Most rulers in the world decide to rule because ruling is a position of power and usually comes with any number of handsome benefits. But this pits the rulers against their subjects. In this system, the rulers do not sincerely care if the people are living well, as this will not affect the comfortable life of the rulers. Just like having wives in common, a Just City needs to find a way to align the interests of the rulers and subjects. This is done in several ways, the first being the absence of private property. The Guardians will own nothing themselves, so that they must depend on others. In this way, the wealth and happiness of the city becomes their wealth and happiness, so their interests will lie in supporting the city alone. In consequence, they will not be able to travel as they please, spend money as they please, or generally benefit from their position as ruler. It is here that Adeimantus notes that this does not encourage the happiness of the Guardians. Plato wholeheartedly agrees, but says, “Our aim in founding the commonwealth was not to make any one class specially happy, but to secure the greatest possible happiness for the community as a whole.” The Just City does not bestow happiness randomly, but in such a way that “the several classes may be allowed such measure of happiness as their nature will compass.” In other words, the Just City enables people to be just as happy as their nature would justly allow. This is certainly a hazard to the adoption of his plan, and Plato does not give a reason as to why he thinks this part of the plan is possible. He has a broader goal in mind.
At this point, it is becoming painfully obvious that this plan might only be a dream, and it is so difficult to enact that it will almost certainly never be done. Therefore, Plato moves into considering what would be the smallest change in the current system that would be sufficient in bringing about the Just City. He claims that if “philosophers become kings,” then this one change would cause the Just City to be established. Later, he observes that not only is this enough to begin the Just City, but until the king is a philosopher, the Just City will never be established. Combining these two propositions, the establishment of the Just City consists entirely of the institution of a philosopher-king. It cannot be done until a philosopher becomes king, and once a philosopher becomes king, it will be done. Though this is only one change, it is a difficult change for two reasons. First, real philosophers are rare, and to reach their full potential they require a very specific up-bringing. Second, people generally do not like them, and it is very unlikely anyone will agree to be ruled by them. Plato quips, “The critic is right in calling the best sort of philosophers useless to the public; but for that he must rather blame those who make no use of them.” Rather than allowing themselves to be directed by the philosopher’s insight, the public punishes dissidents with “disenfranchisement, fines, and death.” Here, Plato is undoubtedly referring to the fate of Socrates. Despite all this, Plato holds out hope that his plan is possible, saying, “Our institutions would be the best, if they could be realized, and to realize them, though hard, is not impossible.”