Reading up on the tradition of natural law in early enlightenment, I wondered, whether the proponents of natural law theories have been moral realists throughout as I naively assumed at the outset. Initially it seemed save to me so assume that someone who claims that there are norms to be found in nature, be it human nature or the nature of the world in general, will have to conceive that these norms exist and have stable content independent of the epistemic access to these norms by human beings (or anybody else). Having read a bit about the tradition, especially about the transitions between Grotius, Pufendorf and Thomasius, I’m not so sure about that anymore.
Two reasons awakened my skepticism: one the one hand, Pufendorf is at least by one author (Hochstrasser) described as turning against the moral realism of his predecessors. Second, there seems to be a role of human history in determining the content of natural law. If that role is merely epistemic, this would not speak against moral realism, but if human history had an influence on the content of natural law, this would cast doubt on realism.
In addition, it seems that another original intuition I had about the realism of natural law theory was overly simple: The model I had in mind was that at least the continental authors more or less assigned nature the theoretical position formerly held by a deity. If that simple model were adequate, it would speak for a simple version of moral realism. However, there are a number of contemporary and modern authors, who suggest that there is no simple switch deity-or-nature, but a more complex re-arrangement in the theory, which includes a significant role for fictive or real human covenant into the genesis of morality and its content. Other authors on the other hand (Hartung) stress the continuity, at least in the conception of obligation, between moral theology and natural right theory.
It turns out that natural law theory is much more nuanced and much more complex than some forms of modern moral naturalism. Thus possible comparisons as hinted at last September need to be much more local, not comparisons to natural law, but comparisons to one theorem of one author.