160 Reason and Its Rivals (ca. 1550– 1815)detail. Only with diffi culty can the many gems of Grotius’s thought be sepa-
rated out from heavy silt of pretentious humanist scholarship. But Grotius at
least provided a new label for the man- made law between states: the “volun-
tary (or volitional) law of nations” (ius gentium voluntarium). Despite the
inferiority of his treatment of the subject as compared to Suárez (whose
prior work he did not acknowledge), it was Grotius’s exposition that exerted
by far the greater infl uence on later writers. Th e race, it has been acutely
observed, is not always to the swift est.On Natural Law
Grotius’s conception of natural law, like Suárez’s, was squarely in the line of
rationalist thought from the Middle Ages. His defi nition of natural law as “a
dictate of right reason” was virtually identical to that of Aquinas. He ex-
plicitly voiced a preference for a mathematical approach to the subject, with
conclusions rigorously derived from axioms in the manner of Euclidean ge-
ometry. He clearly distinguished natural law from divine law, which con-
sisted of the commands of God. Natural law, as a purely logical system, was
stated to be entirely self- standing, owing nothing to God. In a famous state-
ment in his prologue, Grotius went so far as to assert that, even if there were
no God at all, natural law would still exist in its full and complete form.
On this basis, Grotius is sometimes credited with achieving the “secular-
ization” of natural law. Th is is woefully incorrect, since natural law had been
a secular body of thought from its inception. Th e rationalist tradition of
natural law in par tic u lar was thoroughly nonreligious in character. Long
before Grotius wrote, Aquinas had expressly pointed out the powerlessness
of God to alter the laws of logic. Suárez, too, had preceded Grotius on this
point, expounding at length, in the Th omist vein, on the powerlessness of
God himself to alter the principles of natural law.
On the Voluntary Law of Nations
Following Suárez, Grotius sharply distinguished the voluntary law of na-
tions from natural law, with the voluntary law governing “the mutual soci-
ety of nations in relation to one another.” Only the terminology was new
with Grotius, not the concept. Grotius agreed with Suárez that natural law