Justice is one of the four cardinal virtues of the Stoic system (alongside φρόνησις — practical wisdom, ἀνδρεία — courage, σωφροσύνη — temperance). Chrysippus defined δικαιοσύνη as ἐπιστήμη ἀπονεμητικὴ τῆς ἀξίας ἑκάστῳ — "the knowledge of how to distribute to each what he deserves." In the Stoic system it is not one of four "separate" virtues but an aspect of the single virtue, the aspect specifically tied to the social nature of the human being: justice is the manner in which practical reason is realised in social relations.

SVF III 262–294 (the doctrine of the four virtues); III 264 (the definition of δικαιοσύνη); DL VII 92–94; Stob. Ecl. II 59–60 W; LS 61. The Platonic background: Resp. IV 433a–434c. Aristotle: Eth. Nic. V in its entirety. In Marcus the form δικαιότης (a contraction of δικαιοσύνη) at Med. 2.5; 3.6; 09-31 (δικαιότης in what is "from your own cause": justice as the discipline of action); 10.11; 12.15. The full form δικαιοσύνη — 05-12 (among the true goods is δικαιοσύνη, against the seeming goods of the many); 05-34 (the good lies in a just disposition and action, ἐν διαθέσει δικαίᾳ); 06-47 (to live μετ’ ἀληθείας καὶ δικαιοσύνης, benevolent even to liars); 06-50 (to act when ὁ τῆς δικαιοσύνης λόγος leads); 07-54 (κατὰ δικαιοσύνην toward the people at hand — the second member of the triad); 07-63 (souls are deprived of δικαιοσύνη too against their will — hence gentleness); 08-39 (δικαιοσύνη has no counter-virtue in the rational constitution — there is no "too much" of it); 10-11 (ἀνῆκεν ὅλον ἑαυτὸν δικαιοσύνῃ μὲν εἰς τὰ ὑφ’ ἑαυτοῦ ἐνεργούμενα — to justice in what is his own, to the nature of the Whole in all else); 11-01 (οὐδὲν διήνεγκε λόγος ὀρθὸς καὶ λόγος δικαιοσύνης — right reason and the reason of justice differ in nothing: justice is not added to rationality, it is rationality in relation to others); 11-10 (ἔνθεν μὲν γένεσις δικαιοσύνης — justice derived neither from duty nor from contract but from cosmology; and on it the remaining virtues "have their standing"); 11-20 (the ruling part is constructed πρὸς ὁσιότητα καὶ θεοσέβειαν no less than πρὸς δικαιοσύνην, and piety is called not a neighbouring virtue but a species of εὐκοινωνησία — "older than acts of justice"). In Book XII — 12-01 (δικαιοσύνη spelled out as "to speak the truth freely and without disguise and to act κατὰ νόμον καὶ κατ’ ἀξίαν" — a definition by two operations, speech and apportionment); 12-03 (ποιοῦσαν τὰ δίκαια — the first member of the triad of disciplines); 12-05 (the justice of the gods as the premise without which the complaint against them could not have been made at all). And 12-15 (δικαιοσύνη is the second of the three names that must not be put out before you are: ἀλήθεια, δικαιοσύνη, σωφροσύνη). And 12-27 (δίκαιον, σώφρονα, θεοῖς ἑπόμενον — the three things more philosophical than any pursuit); 12-29 (ἐξ ὅλης τῆς ψυχῆς τὰ δίκαια ποιεῖν — "with the whole soul"). In Books I–IV: 03-04 (δικαιοσύνῃ βεβαμμένον εἰς βάθος — "dyed deep with justice"), 03-06, 04-03 (patience is called a part of justice).

In 02-05 δικαιότης rounds off the quartet of virtue-tonalities in which one is to act: σεμνότης (dignity), φιλοστοργία (natural affection), ἐλευθερία (freedom), δικαιότης (justice). The inclusion of justice is a structural turn: virtuous action in Marcus is inseparable from "social rightness." Cf. Med. 11.10 — the famous formula: "δικαιοσύνη is not one of the virtues; it is virtue in its social dimension; all the rest (courage, temperance, prudence) are its preconditions." Related to DOGMAoikeiosis (the ontological ground of social ethics) and TERMsynergia (its active expression).