182 Reason and Its Rivals (ca. 1550– 1815)(at least for the most part) voluntarily adhered to. A person who rejected
that thesis would have a very diff erent worldview. He would expect it to be
extremely diffi cult (and perhaps even impossible) to make laws in the fi rst
place, because agreement among the states would be hard to achieve. And
such a person would expect enforcement of laws to pose a serious problem,
too, since states would tend to breach rules whenever they saw their own
interests threatened.
Th e naturalist and Grotian schools can readily be placed along the
international- law spectrum. Take the naturalists fi rst. Th ey can be said sim-
ply (and by defi nition) to congregate at one extremity: the natural- law end.
Th e Grotians, in contrast, were spread across the entire spectrum, with the
sole exceptions of the two end points. All of the Grotians believed (here too,
by defi nition) in the existence of the two kinds of law, but with much room
left for variation in the proportion of each that went into the fi nal product.
Th e natural- law ingredient might be very great, and the voluntary part very
small, or vice versa. Or the mix could be somewhere near even. Indeed, it
could even, in principle, be precisely half and half.
Th e dominance of natural law in this period is immediately evident from
the key fact that the extreme natural- law end point of the spectrum did have
its supporters (i.e., the naturalist school, by defi nition). Th e extreme voluntary-
law end point, however, was (for the present) largely or entirely vacant. Th at
would change, but not until well into the nineteenth century. For the pres-
ent, we will briefl y survey the spectrum, looking fi rst at the rationalist part,
then at the pragmatists, and then at a key fi gure (Emmerich de Vattel) who
was perched very near the center.
Th e Rationalists
Th e rationalists, it has been noted, were those whose position on the
international- law spectrum was in the region where greater weight was ac-
corded to natural law and lesser weight to state practice. Within this group
was the naturalist school. Th ey were the purists, occupying the extreme end
point, that is, accepting only natural law as the general governing law be-
tween states and rejecting the voluntary law altogether. Foremost among
them, as noted earlier, was Pufendorf. His ac cep tance of the Aristotelian
thesis of natural sociability of humans enabled him to build up one of the