66 Law and Morality Abroad (to ca. ad 1550)period of inactivity, the ius gentium would step in to fi ll the gap. Th e ius gen-
tium, then, was defi nitely inferior to natural law. In an ideal world, which
this one assuredly is not, there would be no ius gentium, but only natural law
in its full and wide- awake splendor.
Th e third school of thought— the emanationist one— posited the closest
connection between natural law and the ius gentium. It was the latest of the
three rivals to appear, and the one that most closely embodied the new ratio-
nalistic perspective. It regarded the ius gentium as fl owing directly from
natural law. As such, it was not quite identical to natural law, but at the same
time was not altogether distinct from it either. Th is theory was supported by
Aquinas, although in somewhat diff erent ways in two separate discussions.
In one treatment, he explicitly endorsed Ulpian’s thesis that natural law was
common to all living creatures and then went on to state that the ability to
derive conclusions from the initial propositions of natural law “by a pro cess
of reasoning” was unique to humans. Th e ius gentium was then described
as the portion of natural law that was discernible only by reason and not by
instinct— meaning, in eff ect, natural law itself in its rationalistic form. In his
other discussion, Aquinas spoke of the ius gentium as being “derived from
the law of nature as conclusions from principles.”
Despite some obscurities, Aquinas’s main point is clear enough. Th e ius
gentium is a man- made law, but only in the very restricted sense that it is
humans, rather than animals, who are able to employ reason and thereby to
discover what natural law requires in a variety of specifi c cases. Th e eff ect,
then, is that natural law comprises the broad general principles, and the ius
gentium the conclusions which logically fl ow from them. Employing a geo-
metric analogy, we would say that natural law corresponds to the axioms, and
the ius gentium to the theorems— with the two being, of course, intimately
connected by an unbreakable chain of hypothetico- deductive reasoning. On
this view, the ius gentium could never actually contradict natural law, for the
simple reason that it was a logical derivation from that law.
A rapid summary of the three schools of thought can be off ered. Th e du-
alistic position stands apart from the others in holding the contents of natu-
ral law and the ius gentium to be diff erent. An important consequence was
that this theory, alone of the three, gave full scope to humans to craft the ius
gentium as they wished, according to their free will. Th e other two theories
regarded the ius gentium as being an aspect of natural law. Consequently,