A BASIS FOR HUMAN RIGHTS: Norm Geras, Andrew Sullivan, and Ramesh Ponnuru have been writing about this. The best treatment of this subject is Arthur Allen Leff’s Unspeakable Ethics, Unnatural Law, 1979 Duke L.J. 1229 (1979), which is, alas, not available online, even on Westlaw. Leff wrote:

I want to believe –and so do you– in a complete, transcendent, and immanent set of propositions about right and wrong, findable rules that authoritatively and unambiguously direct us how to live righteously. I also want to believe –and so do you– in no such thing, but rather that we are wholly free, not only to choose for ourselves what we ought to do, but to decide for ourselves, individually and as a species, what we ought to be. What we want, Heaven help us, is simultaneously to be perfectly ruled and perfectly free, that is, at the same time to discover the right and the good and to create it.

And here’s a passage from his Memorandum from the Devil, 29 Stanford Law Review 1479 (1977) addressed to Prof. Roberto Unger, who ended his Knowledge and Politics with the plea “Speak, God.” Leff, the least diabolical of people, nonetheless responded in character:

Yes, yes, I know your book ends “Speak, God,” and that I, therefore, am the very antithesis of Him whose reply you so sincerely sought. But after all, a good part of the book is written, if not to me, at least against me. And Knowledge and Politics, despite the meagreness of mortal or divine response thus far, is a very important book, certainly meriting a little diabolical commentary. So hear me, pending Him. It was, indeed, the fact that you ended your work with prayer that first attracted my attention. I am something of a connoisseur of these attempts by scholarly humans to find and describe some meaning in their personal and species existence, and when nonironic divine address comes out of Langdell Hall these days, attention must be paid. . . .

Well, well, let me not be cruel. I know at least as well as you what total separation from Him can lead to in the way of self-deception and bad lines. I tried to replace God with myself, and you tried, as He appeared unwilling to come again, to put your faith in some laughable Second Coming of Man. No hope. As long as you wanted simultaneously to make something in the world–mankind– into the good and still reserve the right to judge its goodness, you were doomed. You were trapped in what, to save time, I might call a Gödel problem: how to validate the premises of a system from within itself. “Good,” “right” and words like that are evaluations. For evaluations you need an evaluator. Either whatever the evaluator says is good is good, or you must find some superior place to stand to evaluate the evaluator. But there is no such place in the world to stand. From the world, only a man can evaluate a man, and unless some arbitrary standards are slipped into the game, all men, at this, are equal.

Or to put it another way, one more congenial, I think, to both of us, by dispensing with God we did more than just free ourselves of some intellectual anachronism. We also dispensed with the only intellectually respectable answer to the ultimate “Why is it right to do X?” It was not so very long ago that most people (and I, too) could and did answer: “It is right to do X because God says so.” That answer was at least intelligible, the only one that did not depend upon mere sublunary assertion, the only one that even if it too involved the transformation of fact into value, was not for that reason insufficient. For assuming that God existed, and had commands, it was He who was evaluating our actions. He was not part of our evaluation system, nor were his evaluations subject, or even amenable, to our evaluations of them.

That does not mean, of course, that God exists, or existing, bothers to evaluate your activities. He may not, literally or figuratively, give a damn. It is just that if He does exist (whether or not He cares), as an intellectual matter your problem of normative grounding would be solved. No more would ethical imperatives consist merely of human beliefs, intuited in privacy, perhaps validated by wide sharing or whatever, but just mortal opinions nonetheless. A belief in God and His will would solve the Gödel problem and would avoid the necessary defeat visited on any attempt to validate a system from within itself.

There are, Professor Unger, not very many possibilities. In fact, there are, I think, just two. The first is that mankind is a species that doesn’t mean anything at all, except to itself. There is no evaluator out there. If the species is or becomes one thing or another, or ceases to exist altogether, nothing else cares–except perhaps some other species which, mostly with joy, might register the ecological impact of man’s extinction. You are what you are, and will become what you will become, and the goodness or badness of that being and becoming is for you, and you alone, to define and declare. No state of being is more authentic than any other or, just because it exists, any better. Oh, it’s not so awful. If being isn’t meaning, and it isn’t, meaninglessness isn’t nonbeing either. You and the species get to live. It’s just that you have to shape your living, and its meaning, all alone.

The second possibility is that God exists, and still cares. My own opinion is that the Hand that holds you suspended over my fiery pit doesn’t abhor you, but has forgotten completely that It has anything in It. But God may still care, and, if that is so, you have but one epistemological problem, to learn the will of God. If there is no God, everything is permitted; if there is a God, it’s even more terrifying, because then some things are not permitted, and men have got to find out which are which. Since He has the right and power to evaluate you, but no duty to do so, you are bravely right: you must pray.

But while you try to live as best you can until His revelation, perhaps you will accept some practical advice from me. Look around you at your species, throughout time and all over the world, and see what men seem to be like. Okay? Now take this hint from what you have seen: If He exists, Me too.

The older I get, the more profound this seems.

UPDATE: You can get Unspeakable Ethics, Unnatural law online through JSTOR, if your university or public library has a license. Thanks to reader Dale Belhoffer for the tip.