Final answer:
Plato's theory of justice centers on the idea of societal harmony achieved through specialization and the proper functioning of all societal roles. His vision of a just state includes guardians who rule wisely and without corruption, and individuals fulfilling their roles without meddling in others'. Thus, justice is a collective concept ensuring social harmony and the greater good.
Step-by-step explanation:
Plato's concept of justice was that it transcended the individual and was a principle that applied to society as a whole. To him, justice was akin to a harmony that exists when every class in society performs the role to which it is best suited. Justice, therefore, was deeply intertwined with the idea of specialization and the functionality of roles within the state. Just as he believed that equals should be treated equally, this principle extended to the notion that each part of the society should fulfill its natural function for the whole to operate harmoniously.
Plato envisioned a society where the concept of a just state mirrored the justice found in the individual. A just society would be structured around the mutual needs and different aptitudes of its people, providing the necessary goods and services, trade, wages, and protection, all headed by a class of guardians. These guardians were to be philosophers, uncorrupted by power and fully attuned to the true form of justice. His ideal government was one of meritocracy, where the most capable governed for the prosperity of the whole, not the few.
True justice, in Platonic thought, required each individual to perform their duties without interference in others' roles. It was about fulfilling the duties of one's station in life and contributing to the well-being of the state as a whole. For Plato, this structured approach would prevent disintegration and create a society that is strong and capable of survival.