Plato one of the eminent and vital political philosophy book is the republic. He starts his book with the theory of justice in his literary style of dialogue. According to Plato an individual has three cognitive or perceptual powers of mind, which are as follow, reason, courage and appetite. The interrelationship among the three faculties is called justice. He believed that, if all the faculties of individual mind work properly and under the supervision of reason, then the demand of justice will be full filled. By reason he meant wisdom, and by courage he meant spirit and by appetite he meant desire.
Plato have compared individual mind with state. According to him, state is enlarged or magnified form of an individual. Now here Plato moved from micro to macro level, like human facilities state also has three element. Which are as follow guardian, artisans and warriors. The reason part in ideal state is played by guardian, courage part is played by warrior and appetite part is played by artisans. According to Plato justice in the state refer to, these three classes (guardians, warrior and artisans) which should be present and functional in the state.
Plato believed that, the justice in the state demands that, these three elements should perform their duties and functions individually, one should not interfere in others duties and functions but, artisan and warrior should work under the supervision of guardian. By artisan Plato meant producers, by warrior he meant soldiers or Army and by guardians he meant rulers or government. Society needs basic necessities which are produced by the artisans. People in state need security from foreign aggression, which is provided by warrior or army. State need regulation, which is provided by government and rulers or guardians.
There are two aspects of Plato’s theory of justice. On micro level it is individual and on macro level it is state or society. Micro aspect purpose is to refrain individual from selfish impulses. It also teaches an individual not to meddle and interfere in other work and business. From social point of view in state every institution perform its own function. Somehow both individual minds and state are identical and both do not interfere in others work. Platonic theory of justice is basically of non-interference.