Plato's Republic describes a society that is completely rational, based on Plato's concept of the good life and developed to create and protect that sort of life within the context of a civil state. What Plato seeks in this dialogue is a definition of the perfect life and the perfect state to promote and sustain that life. The Ideal State is a concept and not a reality, either in Plato's time or since. Much of what Plato embodies in the Ideal State is probably a reaction to imperfections in the government and society of his time since he lived in a time of turmoil and warfare, and he created a society that would be free of strife if it lived up to the ideal. The fact that few would want to live in the society Plato proposes may be because Plato ignores or subsumes human nature, and for his perfect society to work to protect the perfect life, it would have to be made up of perfect people. Plato tries to address this through education and other means, but in the final analysis his Republic must remain an ideal only, and to a great extent one man's ideal. David Sachs argues that Plato committed a fallacy in his thinking when he considered the central issue of the relationship between justice and happiness in the ideal state, and he offers an analysis of The Republic to show how this occurred and its consequences.
Socrates speaks of many of the elements to be found in the Republic in terms that show they are ideals to be sought rather than something that can actually be attained. Much of the discussion centers on the question of justice and the achieving of justice. When individuals offer Socrates examples of justice as the answer to the question of what justice is, as Cephalus does in Book I by suggesting that justice was a matter of paying debts, Socrates refuses to accept an example as an answer. An example is only another Form. There must be a quality that can be reduced no further and that can be called "justice." This...