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In the opening of his book of Regulae, the Roman jurist Ulpian states that ‘justice is the constant and enduring will to distribute to each his right’ (iustitia est constans et perpetua voluntas ius suum cuique tribuendi, Ulp. in Just. Dig. I.1.10). As justice is a relatively abstract concept at some remove from the very practical focus of juristic discussions, scholars have often used this line to investigate Ulpian’s philosophical allegiance. The communis opinio seems to be that he took this definition from the Stoic Chrysippus (most emphatically Winkel 1988, who is elevated to common knowledge by Johnston 2000). But as Ulpian also seems to espouse ‘fundamentally un-Stoic’ elements at other places, it has even been argued that Ulpian is an ‘eclectic’ (Johnston 2000:621, digesting a lot of scholarship). In this paper, I will argue—against this reductive view—that Ulpian’s definition is not derivable from any particular source, but should be seen in terms of a ubiquitous philosophical maxim. This argument will be made in two steps.

First, the second part of the definition, suum cuique tribuendi (generally without ius), is widely attested (in all kinds of variants) in Greek and Latin literature in explicit reference to the concept of justice (e.g. [Plato],Aristotle, [Aristotle], Diogenes of Babylon, Andronicus Rhodius, Cicero, Arius Didymus, Livy, Lucian, Galen, [Galen], the scholia on Aristotle, Tryphoninus, Diogenes Laertius, but NOT in Chrysippus (notwithstanding SVF’s listing of 13 fragments)). Interestingly enough, it is found in many so-called doxographical texts across the philosophical spectrum (e.g. the [Platonic] Definitiones, the Peripatetic De Virtutibus et Vitiis, Arius Didymus’ Stoic Doxography), and Cicero also presents the definition several times in the context of different philosophical sects (e.g. Fin. V.65, Leg. I.19, Rep. III.24)). This suggests that it has no distinct philosophical flavour.

Secondly, the element constans et perpetua voluntas is a hapax, and it is unclear to what concept in the philosophical definitions (of the texts listed above) it is supposed to refer (epistÄ“mÄ“, phronÄ“sis, hexis, dynamis, affectio, prudentia). In any case, a connection with Stoic doctrine seems problematic, as voluntas is at odds with virtues' (including justice) being purely intellectual (e.g. Galen Plac.Pl.Hipp. VII.2). It may be transforming a Stoic notion (hexis, boulÄ“sis) without carrying Stoic baggage. As, however, it may similarly have been inspired by [Platonic] and/or Peripatetic hexis, the point is not so much about tracing Ulpian’s source as it is about Ulpian taking up and twisting a popular catchphrase to open his Regulae with. And as these are works containing brief statements of law without arguments (Stein 1966), this would be the kind of prefatory topos we would expect.

At the end of the day, this poses questions about the way we think about Roman jurists (e.g. the philosophical texts they read), ancient philosophy (e.g. notions such as ‘the’ Stoics and ‘eclecticism’; the focus on canonical authors), and their relationship (e.g. the question as to what we mean by philosophical influence; the apparent wish of modern scholars to see jurisprudence in terms of legal philosophy).