264 A Positive Century (1815–1914)positive law was enforceable law. He was a strong believer in natural law
while at the same time conceding that, in practical terms, positive law had
the greater importance.
A German lawyer named Carl von Kaltenborn was another fi gure of this
persuasion. He wrote a book in 1848 on the forerunners of Grotius. In his
rejection of the old rationalistic, hypothetico- deductive style of natural law,
he showed clear evidence of positivist tendencies. But he regarded state
practice merely as data— with the true task of the legal scientist being to
distill theoretical general rules from this body of evidence. In other words,
he favored using an inductive method to arrive at a comprehensive, coherent
system that would be of eternal and objective validity. Like G. F. von Mar-
tens, he may be described as being positivist in his method, but without
adopting positivism as a philosophy.
Similar in outlook— and much more infl uential than Kaltenborn— was the
French lawyer Henry Bonfi ls, who was a professor of law at the University of
Toulouse. His Manuel de droit international public (Manual of Public Inter-
national Law), fi rst published in 1894, became the most prominent exposi-
tion of the subject in the French- speaking world. In it, he expressly endorsed
Grotius’s twofold division of law. Th e natural- law part of law, he explained,
received a variety of diff erent labels— primitive, necessary, absolute, natural,
rational, theoretical, and so forth. But the basic idea was that this body was a
source of rights and duties in its own right, apart from positive law. Bonfi ls
identifi ed a number of principles t hat he at tributed to t his nonpositive source:
the right of commercial liberty of states, the law of neutrality, the principle of
nonintervention, immunities of states for offi cial acts, the right to conclude
treaties, and the principle of pacta sunt servanda. All this was in contrast to
positive law, which he characterized as “contingent, variable, secondary.”
Squarely in the spirit of Grotius and Vattel, he held this part of international
law to be of a lesser status than natural law, as it served merely to regulate
matters that natural law theoretically prohibited. He explicitly referred to his
outlook as falling into “the eclectic school” of international law.
Bluntschli and Lorimer
If natural law continued to survive the blows of the positivists and to be ac-
knowledged by writers throughout the century, a few fi gures made creative