Plato’s Theory of Justice Summary

In Plato’s Republic he defines justice as “doing one’s own work and not meddling with what is not one’s own” (Plato 139, 433b). This definition begs the question what is one’s own work? Plato states that one’s own work is the work that one’s nature is best suited for, as each person is born with a different nature (Plato 101, 370b). To come to this definition Plato compares justice within the human soul to justice within a city. If Plato can find justice within the city and prove that the individual is only a smaller version of the city then he will have found the form of justice, the aspect by which we recognize justice in anything else.

In Book II of Republic Plato constructs a city from scratch because he claims that it is much easier to find justice in a city, than to try and look for it in a single man (Plato 100, 368d). In this city he places a variety of different craftsmen (Plato 100-103, 369d-371e), which correspond with the appetitive element of the soul, auxiliaries to guard the city, corresponding to the spirited element, and guardians to rule over the city, as the reason rules over the soul (Plato 104, 374e).

Plato proposes that each person within his city has a defined role, based upon his or her nature, because a city benefits more “if each person does one thing for which he is naturally suited” (Plato 101, 370c) as opposed to performing many different roles. This is similar to how he defines that each element of a person’s soul has its own task for which it is naturally suited. In defining this Plato asserts that each person is happiest performing his or her naturally defined role and that in doing so they would make the whole city as happy as possible (Plato 130, 420b-c).

After Plato finishes defining his city and the roles of each of its three classes he is now free to attempt to find justice within his city. He does this in Book IV by first finding three other virtues, wisdom, courage and temperance, allowing that what is left in the city is justice. He finds wisdom in the rulers, because their wisdom is what governs and rules (Plato 136,428e). He finds courage in the auxiliaries’ defence of the city (Plato 137, 430a). Plato then finds temperance in the way that the guardians and auxiliaries use their wisdom and courage to master the appetites of the craftsmen (Plato 138, 431d).

What is left is justice, that thing which allows all the other virtues to be found, because by doing one’s own work and not meddling one does not disrupt this natural order. Plato now has a working definition of justice, but for it to be the true form of justice he must prove that it can be found in the individual as well as the city. In Book IV of Republic, Plato distinguishes that there are three elements to a human’s soul. These elements are the rationally calculating element, the appetitive element and the spirited element (Plato 143-144, 439d-441a).

When each of these elements performs its function without interfering with the others Plato calls this person just. The rationally calculating element, also known as one’s reason, rules over the soul because of its wisdom and foresight. Musical and physical training allow the reasoning element and the spirited element work in harmony. The spirited element obeys the reason and aids it in controlling the appetitive element, which overlooks a soul’s different desires. When reason and spirit allow the appetitive element to control them a person becomes unjust (Plato 145, 441e-442b).

To complete his original argument, that justice in a city is comparable to justice within a person, Plato then likens these different elements to the different virtues embodied in his created city, courage, wisdom, temperance and justice. A person’s courage is contained within his spirited element, as a city’s courage was contained within its auxiliaries. A person’s wisdom is contained within the reason that rules over him, as the philosopher king’s ruled over Plato’s city.

Temperance was found in the agreement to allow the rationally calculating element to rule over the soul, as the craftsmen and auxiliaries allowed the philosopher kings to rule over them (Plato 145, 442c-d). Justice is each element working in harmony with the rest, never overstepping their bounds, as within the city it was doing one’s own work and not meddling with others. Plato has now shown that each element from the city is also found within the individual in the same context, proving he has found the form of justice.

Using his argument of a macrocosm reflecting a microcosm Plato was able to define the form of justice. Plato’s definition of justice can be put in a different manner. He believes that justice is a policy of non-interference. Each element of the whole, whether it is in the city or the individual, functions in its own aspect to benefit the whole, fulfilling its own purpose. Justice occurs when the elements of the whole are acting in accord with one another. Works Cited Plato. “Republic. ” Classics of Moral and Political Theory Fourth Edition. Ed. Michael L. Morgan. Indianapolis: Hackett Publishing Company, 1992.