Plato’s philosophy on a just government is well highlighted in The Republic, referring to the best form of government and the best possible person to head such a government. He cites that only a philosopher, a lover of truth, knowledge and wisdom, can rule a just government that is not bent on corruption, tyranny and injustice. Without using force or fraud, a just leader upholds integrity, transparency and moral uprightness in running the day-to-day affairs of a Republic. Furthermore, he ensures that justice prevails in the ruling and decision-making while presiding over the State.
Plato talks about four types of governments in detail in The Republic. These include Spartan polity, oligarchical, democratic and tyrannical. He says, ‘The four governments of which I spoke, so far as they have distinct names, are, first, those of Crete and Spartan, which are generally applauded; what is termed oligarchy comes next – this is not equally approved, and is a form of government which teems with evils; thirdly, democracy, which naturally follows oligarchy, although very different, and last comes tyranny, great and famous, which differs from them all, and is the fourth and worst disorder of a State.’
Although Plato talks in favour of democracy as the best form of government, he cautions that the leader, a stoic philosopher, should be someone whose consciousness is bent on the truth, not as he understands it, but as it is. He should cultivate the pursuit of truth, knowledge and wisdom without compromising on the core just values and vices while presiding. He should be of a chaste soul. Since a philosopher is the only person who uses reason, integrates logic in his thinking, and makes analytical and objective decisions, he is the only qualified person who can be the best leader in delivering justice and democracy in a Republic. He is a man who is a qualified leader who presides and precedes other men, as he is not driven by selfish agendas aimed at enriching his life and that of his family. He puts the interest of a just State above any personal gain or interest. He wears the yoke of good leadership over the State around his neck in pride and becomes a mantra of his purpose in life. He is a man driven to 
deliver justice, peace and equality in the Republic.
Plato talks about the three classes of worthy men in a just State and their core life’s purpose accordingly. ‘Then we may begin by assuming that there are three classes of men – lovers of wisdom, lovers of honour, and lovers of gain.’ Philosophers fit this cap of the lovers of wisdom as they dedicate their time to pursuing, understanding and interpreting knowledge, truth and wisdom. The second class are men bent on brotherhood. For them, honour means everything. Being in a tribe of men and following the principles of oneness, enriching their lives to be better men, driven by the principles of discipline and commitment, is their way of life. Finally, businessmen take the award of lovers of gain. For this class of men, their actions are bent on profit. They forge their lives in line with the commerce of production minimizing losses and maximizing profits. These are men who ensure the economy of the Republic grows steadily.
Plato, who is an avid admirer of poetry specifically Homer, talks about imitation in both art and life. He attributes learning to imitation as the best possible way to mirror reality, and also as an art to describe nature for instance in a work of art. Men who are lovers of wisdom are able to decipher this and appreciate the works of art. On the other hand, men who are lovers of gain are business-minded and seek after the pleasures of profits in business. To them, art and knowledge mean very little, equally the same to lovers of honour who mind and look after brotherhood and power.
How can we attain a just State? This is a question Plato tries to answer in The Republic. One analogy which he cites as an example is of slaves who spend all their lives chained looking at the wall in a dark cave. They cannot turn their necks as they are restrained by heavy chains. They spend all their days gazing at the wall in the dark cave. They can’t see anything save for the shadows of the fire that burns behind their backs. Their understanding and realities of life are nothing but the shadows of fire that reflect on the wall. This is the only thing that exists on the face of the earth. When these prisoners are released from the cave, they cannot perceive the outside world as it is. They get mortified by what they see, and they imagine it is not real. They long to be back in their prison staring at the wall in the cave, such is the fate of an unjust Republic that is presided over by bad leadership of injustice. The citizens of such a State cannot perceive anything else apart from this oppressive governance of selfishness, injustice, 
corruption, imprisonment and extrajudicial killings and manslaughter.
How can citizens attain a just State? To attain this goal, it is imperative for the citizens to be educated. They must be enlightened in understanding what it means to have a just State and the qualities of a government that can deliver such a desired result. They must second choose a man dedicated to the pursuit of truth, knowledge and wisdom, and that is the philosopher. Such a man will spearhead the qualities of a just government which will lead to a just State. He must be a man who has nothing to gain but everything to lose, who cannot waver or falter his character even in the face of danger or coercion. He will put in place the proper mechanism including men, in the army and the police force, who will enforce policing on the laws set forth as the blueprint of leading a just government.