Reflections on the Relevance of Ulpian’s Natural Law

Lessons from the oracle of jurisprudence

La Dame à la licorne: À mon seul désir (Flemish tapestry circa 1500; Musée national du Moyen Âge, Paris)

The New Digest is pleased to present this contribution from Mr. Hugo Decker. H.G.T. (Hugo) Decker studied at the universities of Hasselt (LL.B.) and Leuven (LL.M.). He is a lecturer at the University of Maastricht (Foundations of Laws) and active as a lawyer at Vanbelle Law (Brussels Bar Association). Hugo's research primarily focuses on where (natural) law meets evolutionary biology.

Proemium. When the Emperor Justinian constructed his ‘Temple of Justice’, the writings of one ‘oracle of jurisprudence’ were firmly imprinted into the Corpus Iuris: the Tyre-born Ulpian (193–235). While Ulpian remains commanding respect by generations of lawyers, his conception of the Natural Law (“quod natura omnia animalia docuit”) – that “unlucky phrase” in the words of Pollock – receives a less warm reception nowadays. In what follows, Ulpian’s conception of Natural Law will be briefly outlined (§1). Thereafter, we examine some of the criticism lobbed at Ulpian (§2). Lastly, we will argue in favour of what could be called an ‘Ulpianistic’ conception of Natural Law’ (§3).

§1. Ulpian defined the Natural Law as: “that which nature has taught to all animals” (D.I.13; Inst. Lib. 1. II). Prima facie, one may suspect a rhetorical meaning; a metaphorical elevation of the Natural Law above mortal command (as in Cicero) and an acknowledgement of its universal supremacy — it rules all animals,including humans. However, instead of metaphorical elevation, Ulpian ‘lowers his gaze’ and intends an actual biological meaning. The following sentence makes this clear:

“[F]or it is not a law specific to mankind but is common to all animals — land animals, sea animals, and the birds as well. Out of this comes the union of man and woman which we call marriage, and the procreation of children, and their rearing. So we can see that the other animals, wild beasts included, are rightly understood to be acquainted with this law” (D.I.13; Inst. Lib. 1. Tit. II).

While Ulpian forges a strong link between (natural) law and ‘nature’, the character of this link remains somewhat murky — troubling the minds of many medieval jurists. For instance, what are these ‘teachings’ of nature? Are they biological impulses and (if so?) by this quality precepts of the Natural Law? Or, does Ulpian only denote a necessary but not sufficient condition — i.e., precepts of the natural law are anchored within nature but that, in itself, is insufficient?

Furthermore, the strong connection Ulpian forged between (natural) law and biological facts remains, in the words of Crowe, a “special case”. While weak(er) connections with nature could sometimes be present, the focal point within the Natural Law tradition lies on ‘reason’; on reason being part of and ruling human nature. For instance, compare how Diogenes Laertius describes Stoicism and St Aquinas with Ulpian:

“When, in the case of animals, impulse is added, by means of which they pursue what is appropriate for them, then for them what is natural is to be governed by impulse. And when reason, as a more perfect authority, has been bestowed on rational beings, then for them what is natural and proper is to be governed by reason. For reason, like a craftsman, overrides impulse”;

“All the inclinations of any parts whatsoever of human nature, e.g., of the concupiscible and irascible parts, insofar as they are ruled by reason, belong to the natural law, and are reduced to one first precept, as stated above […].”

§2. For contemporary thinkers the problem is not so much the vagueness of Ulpian’s definition or its ‘special’ position within the Natural Law tradition, but the straightforward connection between law, ethics and nature, casu quo biological facts. Legal and moral norms prescribe how people should live their lives. On the other hand, biological facts are purely descriptive; they describe a state of affairs to the best of our current knowledge.

Furthermore, nature ‘teaches’ more than only having offspring (setting aside whether procreation would always be moral); it also instructs violence, deceit and opportunism. Leaving aside the logical problems (deriving an ‘ought’ from an ‘is’), on what basis do we select this teaching from nature (e.g. investing in children) while rejecting another (e.g., murdering a rival)? Ulpian’s formula does not provide an answer.

§3. However, excessive attention towards the ‘naturalistic fallacy’ and adjacent problems obscures a cardinal lesson implicitly contained within Ulpian’s Natural Law: humans are and remain biological creatures. Consequently, we share several challenges – albeit often more complex – with other (social) creatures. Who to trust? Who and what qualities make – in the language of the biologist – a suitable mate? Or, how should we cooperate and maintain cooperation? (The referenced literature contains, for the curious reader, some useful entries).

§3A. Evolutionary inquiries seem, for understanding this part of our existence, especially informative. Three elements deserve to be highlighted in this respect. First, evolutionary theory is occupied with so-called ‘ultimate causes’ — i.e., answers to why questions such as ‘why do we dream?’, ‘why do we care about our reputation?’ or ‘why do male chimpanzees prefer older females?’. We seek, to cite Mayr, “[to identify] causes that have a history and that have been incorporated into the system through many thousands of generations of natural selection.”

Second, the influence of our evolutionary heritage is not limited to the working of our eyes or the shape of our legs. On the contrary, our ancestors’ cognitive and social (including moral) capacities equally determined whether they would survive and reproduce. Indeed, as Boehm notes:

“[A]ll human groups frown on, make pronouncements against, and punish the following: murder, undue use of authority, cheating that harms group cooperation, major lying, theft and socially disruptive sexual behavior. […] It’s clear that ‘biology’ and ‘culture’ have been working together to make us adaptively moral”.

Third, our liberty to ignore these features is often not absolute. From men being less satisfied with their existent relationship after seeing numerous pictures of attractive women (which, in essence, follows from an evolved psychological complex saying, ‘see all these beautiful women, you can improve your current situation!’), to being evolved to spot animals and other humans faster than cars: our evolutionary heritage cannot simply be discarded.

§3B. On the contrary, our evolutionary heritage needs to be studied and understood instead of being discarded. First, our biology influences (and sometimes limits) which patterns of social organisation – and, ultimately, their legal articulation – are possible. For instance, Peter Turchin (an evolutionary biologist turned historian) notes:

“Long-term social ‘experiments’ – attempts to impose a new morality from above – show that social norms and institutions which go strongly against human nature do not ‘take’, no matter how hard they are promoted. [… For example, the Soviets] abolished marriage. This innovation did not ‘take. Marriage was brought back in the 1940s, and by the time I was growing up in the 1960s and 1970s, very few couples who lived together with children were unmarried”.

Second, it provides an explanatory role for many principles of positive law. For instance, would ‘exclusion’ (including the unsatisfactory feelings accompanied by it) be an issue if humans were solitary instead of social animals? Indeed, concerning our positive law, the same reason as Fukuyama developed vis-à-vis the foundations of our political institutions applies:

The recovery of human nature by modern biology, in any case, is extremely important as a foundation for any theory of political development, because it provides us with the basic building blocks by which we can understand the later evolution of human institutions”.

Third, there are more practical reasons. Here, one aspect deserves particular attention: our intuitions — i.e., reactions which are fast, implicit and difficult to control. Without a doubt – following our evolutionary scheme – the ability to act fast and unreflective proves handy when facing a boa constrictor or jaguar. However, intuitions are not restricted to the bread-and-butter aspects of survival. On the contrary, our moral judgements are often dominated by these fast, automatic, and emotional processes instead of ‘moral reasoning.’

This idea was tested by Haidt’s ‘moral dumbfounding’ studies. The crux is as follows: participants are confronted with stories characterized by ‘highly original’ behavior – from having intercourse with a chicken or eating your dead pet to sexual activity between siblings – coupled with an absence of harm. Despite the absence of injury and damage, participants quickly qualify the behavior as immoral.

Moreover, when they are reminded of the lack of harm (e.g., the siblings used birth control, hence no danger for interbreeding), participants say something such as: "I don't know, I can't explain it, I just know it's wrong"— indicating, as Haidt suggests, the primacy of moral intuitions (the feeling that something is wrong) to moral reasoning.

What would happen to our legal systems when these moral intuitions would be gravely contravened? Robinson and Darley elegantly argue – at least concerning criminal law – that:

“[T]he effective operation of the criminal justice system depends upon the cooperation or at least the acquiescence of those involved in it—offenders, judges, jurors, witnesses, prosecutors, police, and others. To the extent that people see the system as unjust or failing to do justice, as in conflict with their judgments about justice, that acquiescence and cooperation is likely to decline and even disappear. But more than that: to the degree that these deviations are frequent and morally consequential, active forces of subversion and resistance are generated in the community.”

§3C. Instead of its current ‘airy’ and almost detached character, ‘moral intuitions’ and biological features belonged to the Natural Law. Helmolz, for instance, notes:

“Although the two senses of the term natural might appear to stand at odds – the one a basic instinct shared by animals and humans, the other a more refined sense of justice – the primary and secondary senses of the law of nature were not then regarded as opposites.”

Indeed, Natural Law was, historically, a living and breathing instrument — intimately connected to the moral intuitions of ordinary people, their ‘hunches’ – to use Hutchinson’s terms – and their moral gut feeling. Up until the early 20th century, these ‘gut feelings’ or ‘moral instincts’ found their way, as Natural Law, into case law. For instance, the Supreme Court of Georgia stated:

“[T]he right of privacy has its foundation in the instincts of nature. It is recognized intuitively […] A right of privacy in matters purely private is therefore derived from natural law”.

§3D. How do we make sense of this? On the one hand, humans face the constraints of their nature, particularly their biological nature. On the other hand, many ‘teachings of nature’ are problematic (supra. §2). Not surprisingly, Aquinas seems to offer an interesting refinement. The great doctor of the Church starts by distinguishing three inclinations - in ascending order – present within human nature.

First, there is the inclination we share with “all substances” (e.g., seeking self-preservation). Second, there is the inclination we share with other animals “and”, writes Aquinas, “in virtue of this inclination, those things are said to belong to the natural law, which nature has taught to all animals” (e.g. procreation). Third, there is the inclination proper to humans, the capacity for reason (e.g., knowing God, communal life, and so on). Hence, while we share certain inclinations with plants and animals, human nature is much richer.

Ulpian, by limiting himself to these two inclinations, misses, according to Aquinas, our most distinguishing feature: our reason, our capacity to pursue – without being simply dependent upon instinct – our ingrained end, our capacity to live a human life instead of merely following natural cravings. Indeed, as Budziszewski writes:

“We seek not bare life, but a human life, which is a considered life. We seek not the bare union of male and female, but marriage — the sole mode of union suffused with the meaning of union, with the awareness of mutual self-gift between beings who can mutually make, and thoughtfully care for, new life. We not only follow our inclinations, but wonder about them and inquire into them, just as we wonder about all things.  

Nevertheless, this does not imply the insignificance of our biological heritage. On the contrary, and here proves Ulpian his worth, it may inspire us to ask new questions, to study the integral human condition, to follow the questioning spirit of the psalmist who asks:

“When I see your heavens, the work of your fingers, the moon and stars that you set in place—

What is man that you are mindful of him, and a son of man that you care for him?”

Conclusion. While Ulpian’s conception remains vague (§1) and faces numerous philosophical problems (§2), it puts – if lawyers are allowed to use ‘catchphrases’ – the natural back into ‘Natural Law’ which is a rewarding exercise for a couple of reasons. First, it challenges us to take human nature seriously, especially considering its biological roots. Certainly, ‘man does not live by bread alone’, but bread or, in this case, our biological roots, cannot be neglected. Second and adjacently, it invites us to examine our limits, the limits of our social organisation and ultimately, the law by which the patterns of our associations are expressed. Third, it helps with explaining the ultimate ratio behind certain principles of positive law. Fourth and last, an ‘Ulpianistic’ conception would (re)connect the Natural Law with modern science — or, how the jurist from Tyre remains relevant in this day more than ever.