184 Reason and Its Rivals (ca. 1550– 1815)It was in his fi nal years at Halle that Wolff toiled on a great summa of
natural law that, in terms of bulk, left even Grotius and Pufendorf far be-
hind. If Gustavus Adolphus had taken Wolff instead of Grotius as his night-
time reading choice, he would have needed a very capacious bed. Published
in 1740– 49, Wolff ’s exposition weighed in at nine very heft y volumes. Never
had an academic spider woven so marvelous a conceptual web. With his
excruciatingly thorough application of the hypothetico- deductive method,
Wol ff could be called the last of the medieval scholastics. Indeed, he had
received a Catholic education in his youth (although he was a Lutheran by
faith) and had a strong sympathy for the grand unitary outlook of the Mid-
dle Ages. He candidly admitted a great intellectual debt to Aquinas.
Th e fi nal volume of the grand masterpiece was devoted to the subject of
international law. Th is was published in 1749, with the apposite title of Th e
Law of Nations Treated According to a Scientifi c Method. Like Grotius, Wolff
resolutely excluded current events from consideration. Unlike Grotius,
though, he eschewed the humanist adornments of classical and biblical his-
tory in favor of a straightforward exposition and application of reason. His
work therefore has a directness that is all too lacking in Grotius.
Wol ff was a Grotian, rather than a naturalist, in that he accepted the exis-
tence of a man- made law of nations in addition to the law of nature. Th is
allegiance to the dualistic tradition of Grotius is immediately evident from
the subtitle of the book: “In Which the Natural Law of Nations Is Carefully
Distinguished from Th at Which Is Voluntary, Stipulative and Customary.”
But if he was a Grotian, then he was one who perched very near to the ex-
treme naturalist end of the international- law spectrum.
Fundamental to Wolff ’s rationalistic system was the core principle of the
quest for “perfection” by states. Th is required rulers to work diligently to
develop the various capacities of their states to the greatest extent possible.
Th is duty that states owed to themselves was primary. Aft er that, and sec-
ondarily, came duties owed to other states.
Although the subtitle of Wolff ’s opus identifi ed four kinds of law, he read-
ily acknowledged the fundamental Grotian distinction between natural law
and man- made law. Natural law was what Wolff called the “necessary law of
nations.” More strictly, it was the subportion of natural law that was appli-
cable to the specifi c subject of interstate relations. It was “necessary” in a
logical sense, in that it was deducible from the axioms of natural law in the