This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
The most distinctive claim Stoic ethics makes about justice is cosmopolitan rather than civic: dikaiosyne is owed to every rational being, not only to fellow citizens of one's own city. This followed from the Stoic doctrine that the whole cosmos is a single community bound by shared reason, logos, so that a slave, a foreigner and a citizen alike are, at the level that actually matters to ethics, fellow members of one polis, the kosmopolis. Diogenes Laertius records Zeno's own Republic as arguing that all inhabitants of the world should not be separated by their several states and codes of law, but should regard all as fellow citizens, a strikingly universal claim for its time.
This reasoning gave dikaiosyne a scope that classical Athenian justice, tied closely to the rights and duties of a citizen within one city-state, did not have. Stoic writers extended it in practice to arguments against ill-treating slaves and foreigners on the grounds that reason, the one thing that grounds moral standing, is shared regardless of birth or status; the Stoics were not straightforward abolitionists by modern standards, but the cosmopolitan premise unsettled the ordinary Greek assumption that ethical obligation stopped at the city wall.
Roman Stoicism carried this cosmopolitan justice furthest. Cicero, deeply influenced by Stoic sources even where not himself a strict Stoic, and later Marcus Aurelius, writing as an emperor administering a vast multiethnic state, both treated the doctrine of a single rational community as directly relevant to how a person in power ought to govern: justice toward a subject province was, on this reasoning, not a matter of favor extended downward but an obligation owed to a fellow rational being who happened to live under Rome's administration. The line from a school's ethical treatise to imperial self-justification is not a straight one, but the cosmopolitan premise itself outlived the empire that borrowed it, and modern accounts of natural rights and universal human dignity trace a real, documented debt back to this Stoic doctrine of dikaiosyne.