Roman Law. It was through the path laid down by
middle Stoicism that the doctrine of natural law
reached Roman jurisprudence. The very ancient
Roman law knew nothing in fact of natural law. Every
law was tied to political allegiance. Once this alle-
giance was over, the law also terminated and the legal
bonds which united the individual to the city were
severed, so that the city was then deprived of any legal
prerogative.
The penetration of Greek ideas was, however, to
modify this point of view, especially after 146 B.C.
when Greece was annexed. The praetor's edict and the
jurisconsults' works were the vehicle for this penetra-
tion, so long as the jurisconsults belonged to the intel-
lectual aristocracy and kept a share of the power, their
influence was consequently decisive on the evolution
of Roman law.
Middle Stoicism, notably that of Panaetius and
Posidonius, made the matter easy moreover, for it
revised the very narrow positions held by the original
Stoics, yielding on certain points, and proposing espe-
cially an active morality. “The wise man does not live
in the desert, for he is sociable by nature and made
for action. He exercises to strengthen his body, and
he will pray to the Gods and make vows to obtain
their blessings.”
However, the thought of Plato and Aristotle was for
all that not neglected. They are the source of those
famous definitions: of Law (Jus) as “the art of the good
and the equitable” (jus est ars boni et aequi) by Celsus,
and of Justice as “the constant and perpetual will to
attribute to each his due” (iusticia est constans et
perpetua voluntas ius suum cuique tribuendi) by
Ulpian. These definitions were undoubtedly of Greek
origin.
The famous definition, not of natural right but of
natural law, is formulated by Cicero in his De republica
(3.22.33): “True law is right reason which conforms
to nature” (Est quaedam vera lex recta ratio, naturae
congruens); it is nonetheless Stoic and constitutive of
an ethics whose content is made clear in De inventione
(2.53.161), namely, the law engraved in our hearts, as
are religion, piety, gratitude, vengeance, respect, and
truth.
But if the distinction between law and justice is not
too clear-cut, the distinction between natural law and
the law of the city was soon adopted by the juriscon-
sults who with much less oratory took up again the
Stoics' notion of natural reason enabling one to distin-
guish among the norms those that would qualify as
natural. Gaius, in Book I of his
Institutes (
Digest, I.t.1;9)
taught that “all the civilized peoples govern themselves
partly through the law common to all peoples, and
partly through the law peculiar to themselves, for when
a nation creates a law, it becomes its own 'civil law,'
while the law established by natural reason among all
men is observed equally everywhere and is called the
law of all people (
lex gentium), obligatory on all na-
tions.”
The separation is clearly made, for lack of being well
made: this law of peoples, product of natural reason,
is necessarily the most ancient “for it was born with
the human species” and the compelling character of
natural reason with respect to positive law is undeni-
able. Hence civil law cannot be arbitrary for it is
limited by natural reason (naturalis ratio).
Probably even more stoical is the tripartite division
of Ulpian: natural law, human law, and civil law. This
division reveals the wish to allow nature to play as
extensive a role as possible.
Is the influence of natural law, conceived as stem-
ming from natural reason, only an ornament of Roman
law, a kind of addition to its basis which was probably
quite different, a general introduction to a law which
would have had no use for it?
The answer appears to us subtle. It is certain that
the analysis of the Digest proves that the part played
by natural law in the regulation of an institution like
marriage is important (Digest, Book XXIII, title II, law
14, sec. 2). As a single example: the cognatio servilis
(“slave status”) prevents the marriage of a liberated
slave with his mother, his sister, or his sister's daughter,
and reciprocally a liberated father could not marry a
liberated daughter. The reason: “in marriage the natu-
ral law and the feeling of decency are to be observed”
(in contratendis matrimonis naturale jus et pudor in-
spiciendus est). Likewise, the evolution of the status
of the slave seems to be well based on the Stoic idea
that all men are equal—a line of reasoning contrary
to that of Aristotle. At first, the slave's acquisition of
a name, then of limited property (peculum), and finally,
of the right to manifest and declare his freedom as a
person—all that indicates an evolution based on a
principle borrowed from the Porch of Stoicism.
As for the law of contractual obligations, there seems
to be no exception to its having been conceived with
the theory of natural obligations. On the other hand,
it is true that most of the jurists' works remain works
of casuistry, and to this extent they may be claimed
to be more Aristotelian than Stoical since natural law
never appears in their works dressed in the form of
a deductive system.
