162 Reason and Its Rivals (ca. 1550– 1815)they frequently are in the area of warfare— then the voluntary law of nations
can step in to relieve humans from the strict application of natural law. It
can achieve this by prescribing that some act that violates natural law will
nonetheless be exempt from punishment by earthly authorities. Strictly
speaking, the voluntary law of nations cannot actually alter the natural law
in any way— that is, it cannot transform an act that is unlawful under natu-
ral law into one that is lawful. It can only hold back from infl icting a
punishment.
It is apparent, then, that Grotius (like Suárez) did not break entirely free
of the medieval picture of the ius gentium as being connected to natural law.
Th e principal signifi cance of his voluntary law of nations did not lie in any
assertion of complete in de pen dence of the two. Instead, it lay in Grotius’s
insistence (echoing Suárez and Isidore) that the voluntary law of nations is
wholly man- made and that it is therefore not a direct and ineluctable logical
emanation from natural law. But this thesis, limited and cautious though it
was, was of the highest importance. It proved to be the fi rst step— though no
more than that— toward severing the ius gentium entirely from natural law
and relegating natural law to what was sometimes called the “court of con-
science.” Grotius himself never went anywhere near so far as that. But his
taking the fi rst halting step in that direction was enough to enable the posi-
tivists of the nineteenth century to claim him as a forebear.
Grotius aped Suárez in identifying the fi eld of diplomatic relations as a
key illustration of the voluntary law in action. Another important area was
reprisals. It has been observed that the essence of reprisals, as the practice
had developed in the Middle Ages, was the collective responsibility of citi-
zens for wrongs committed by any one of them against foreign nationals.
Th ere were also cases in which the wrongful act was committed by a sover-
eign rather than a private party— most commonly, in the form of a refusal
or failure to grant justice to a foreign claimant. Since taking reprisals against
a sovereign was, in practice, diffi cult or impossible, the voluntary law al-
lowed reprisals to be taken instead against the ruler’s subjects. Grotius ad-
mit ted t hat t his practice of ta k ing action against surrogates of w rongdoers—
rather than against the wrongdoers themselves— was not part of natural
law, which did not allow innocent persons to suff er for the acts of guilty
parties for which they bore no responsibility. But it was not actually contrary
to natural law. Consequently, states were allowed to introduce the practice