In the Republic IV Socrates purposes the argument that the soul has three parts and each corresponds to the parts of the ideal city. His argument is as follows, society should be divided into three distinct classes according to each individual’s natural abilities. (‘More plentiful goods are produced if each person does one thing for which he is naturally suited’1)The three groups which society will be organized into are the guardians, the auxiliaries and the producers. Three virtues are also established by Plato which corresponds to each group which include wisdom, courage and moderation. (‘The state will obviously have the qualities of wisdom, courage, self-discipline and justice’2) The guardians defend the city against its enemies and therefore must have the virtue of courage. (‘We shall say it’s brave with sole reference to the part which campaigns for it.’3)The producers must reign in their own desires in order to be ruled by the guardians and thus must hold the virtue of moderation. (‘Self-discipline can be seen where the desires of the less respectable majority ae controlled by the desires of the superior minority’4) The auxiliaries govern the state and therefore must have the virtue of wisdom. The guardians will have to possess the ‘temperamental inclination towards philosophical thinking’ and they will be trained from a young age in order to become sound rulers of the state. (‘The state is wise as a whole…in virtue of the knowledge...of its smallest class.’5) It is only when all individuals carry out the roles that they are naturally suited to that the state can be harmonious and just. (‘Justice is just the minding’s of one’s own business.’6)

The characteristics exhibited in a just state are the same as those shown in a just individual. (‘There will be no difference between a just man and a just city.’7) When making a decision there are different parts of the human mind that come into conflict. (‘One of the same thing cannot act…in opposite ways at the same time.’8) These competing parts can are the three individual parts of the soul which are rationality, spirited and appetitive. The spirited part conflicts with the desire part of the soul. The spirited part however never conflicts with the rational part. (‘Don’t we see instances of a man’s desires forcing him to do something his reason disapproves.’9) The soul must have three individual part, each part corresponds to a different class within the state. (‘The elements that belong to a state must also exist in the individual’10) The rational part pursues honour and is associated with the guardians. The appetitive part looks for bodily wants such as food, sex and drink and is associated with the producers. The spirited part of the soul carries out what reason informs it to do and is associated with the auxiliaries. (‘We can call the reflective element in the mind reason… the element with which it feels hunger and thirst the element of irrational appetite.’11) An individual is just when all three parts of the soul are in harmony and when spirit and appetite are controlled by reason. (‘We call ourselves self-disciplined when all three elements are in harmonious agreement…when all agree reason should rule.’ 12) In the same way that the state exhibits justice only when everyone is carrying out their role and the producers and auxiliaries are being ruled by the guardians. (‘Interference by the three classes…does the greatest harm to the state’ 13)
Socrates’ premise that there are ‘three individual parts of the soul’ is unsound as there is no evidence other than his own thinking to suggest this notion to be true. Whilst there may well be an appetitive, rational and derisive part to the human soul that does not mean that there are not more parts, perhaps many more. Why should the soul be categorized into only three parts? People are complex, there must be hundreds of different motivations for the choices that humans make. Thus, to narrow the parts of the soul to just three