Law and Ius Gentium in Thomas Aquinas
Collegio Universitario ARCES - Thomas International, Italy
Contemporary international law does not seem
to have much to do with its ancestor (Roman law concept of)
ius gentium. Students, today (and not without reasons),
trace international law back to the early modern
world—particularly, to a strong legal and moral development
mainly attributed to the ground-breaking work of Hugo Grotius.
Confronting these two notions, “international
law” and “ius gentium,” we can adopt, roughly, two main
attitudes. On the one hand, we can assume that they should be
considered by now as totally discontinuous with each other.
Consequently, we can be excused if we limit our attention to one
of the two at the time according that our interests are more
history related or contemporary legal and political issues
related. On the other hand, we can assume that there is a useful
continuity between the two relevant notions that still deserves
attention. In this paper, I adopt the second attitude.
Thomas Aquinas looked closely at the Roman
legal concept of ius gentium, and dealt with it in the
context of his natural law theory. The main problem with his
treatment of ius gentium is that, in different passages
of his work, he seems to consider it at the same time as part of
natural law and as part of human law. This sounds like a
contradiction, and it’s going to be the main theoretical focus
of my discussion.
In this paper, (1) I’ll first give a sketch
of what we mean today by “international law” and of what Aquinas
(and Roman lawyers) meant by ius gentium. (2) Then, I’ll
explain why Aquinas considered ius gentium as part of
natural law. (3) Third, I’ll explain why Aquinas considered
ius gentium as part of human law. The explanation of these
points, will shed not little light on Aquinas’ concept of
natural law, and, I hope, will indicate some interesting ways in
which his idea of ius gentium, even if not up to date
anymore, can still reveal itself useful to international lawyers
and to everybody who is concerned about international political
and moral issues.