An interesting conversation about (the new) natural law

In the latest issue of First Things, David Bentley Hart (an amazing writer, in my view) has a piece called "is, ought, and nature's laws" in which he rejects "the attempt in recent years by certain self-described Thomists, particularly in America, to import this [natural-law] tradition into public policy debates, but in a way amenable to modern political culture. What I have in mind is a style of thought whose proponents (names are not important) believe that compelling moral truths can be deduced from a scrupulous contemplation of the principles of cosmic and human nature, quite apart from special revelation, and within the context of the modern conceptual world. This, it seems to me, is a hopeless cause."

Hart concludes:

To put the matter very simply, belief in natural law is inseparable from the idea of nature as a realm shaped by final causes, oriented in their totality toward a single transcendent moral Good: one whose dictates cannot simply be deduced from our experience of the natural order, but must be received as an apocalyptic interruption of our ordinary explanations that nevertheless, miraculously, makes the natural order intelligible to us as a reality that opens up to what is more than natural. 

There is no logically coherent way to translate that form of cosmic moral vision into the language of modern “practical reason” or of public policy debate in a secular society. Our concept of nature, in any age, is entirely dependent upon supernatural (or at least metaphysical) convictions. 

R.J. Snell responds, here and here, contending -- among other things -- that Hart is attacking a "straw man", because John Finnis's account of natural law is not as Hart describes it.  I'm painfully aware that I'm not close to being competent to referee this debate.  If I have it right, Snell's claim is that the Finnis (et al.) account of natural law does not involve deriving, or "reading off", moral truths from "nature"; it has to do, instead, with (underived) principles of practical reason.  With respect to these princples, Snell writes, "[n]either are they innate, although they are self-evident; grasping them entails 'no process of inference' but rather an 'act of non-inferential understanding.'”  He adds:

Rather than Hart’s “clear commands” for “any rightly attentive intellect,” contemporary natural law requires sophisticated casuistry, which perhaps explains why moral theologians most persuaded by physicalism sometimes accuse contemporary natural law theorists of permissiveness, since natural law theory readily admits the complexities and vagaries of the agent’s intentions. 

Read it all.  (And, maybe also Russell Hittinger.)