Final answer:
The Milesian philosophers did not concentrate on the idea of a just society; their focus was on fundamental natural principles. It was philosophers like Plato who explored justice and the concept of the just city in works such as 'The Republic'.
Step-by-step explanation:
The Milesian philosophers did not primarily argue over the nature of a just society; instead, they focused on identifying the fundamental substance of the natural world.
The Milesian school, consisting of philosophers such as Thales, Anaximander, and Anaximenes, is considered the first philosophical school in the Greek tradition. Their inquiries lay more in the realm of what we would now describe as natural philosophy or early science, as they sought the archē, or underlying principle of the world.
Conversely, it was later philosophers, notably Socrates and his student Plato, who delved more deeply into the nature of justice and the ideal society. In his work The Republic, Plato lays out his vision of a just society, one that is organized according to the principle of specialization and led by philosopher-kings. This is the foundational idea of the just city, where each citizen contributes according to their abilities and leaders rule with wisdom and virtue.