Moral relativism maintains that the natural law cannot exist because morality is different everywhere.  In philosophy, the most influential recent advocate of relativism is Richard Rorty, who writes "I do not think there are any plain moral facts out there in the world, nor any truths independent of language, nor any neutral ground on which to stand and argue that either torture or kindness are preferable to the other."   In jurisprudence, its most influential advocate is probably Richard A. Posner, judge of the U.S. Court of Appeals for the Seventh Circuit.  No babe in the woods, Posner knows better than to flatly deny the reality of moral universals; all cultures recognize the wrong of such things as murder.  Rather than denying the point, Posner trivializes it.  He doesn’t deny that there are moral universals, but that there are "interesting" moral universals.  In his own words:

“[M]orality is local.  There are no interesting moral universals.  There are tautological ones, such as "Murder is wrong" where "murder" means "wrongful killing," and there are a few rudimentary principles of social cooperation -- such as "Don't lie all the time" or "Don't break promises without any reason" or "Don't kill your relatives or neighbors indiscriminately" -- that may be common to all human societies.  If one wants to call these rudimentary principles the universal moral law, fine; but as a practical matter, no moral code can be criticized by appealing to norms that are valid across cultures, norms to which the code of a particular culture is a better or worse approximation.  These norms, the rudimentary principles of social cooperation that I have mentioned, are too abstract to serve as standards for moral judgment.”  ("The Problematics of Moral and Legal Theory," Harvard Law Review, Vol. 111 (1998), p. 1637.)

The argument may be put like this:  Principles like "Don't murder," "Don't lie," and "Don't break promises" may seem to say something, but this is an illusion.  "Murder" means merely "wrongful killing," so "Murder is wrong" translates "Killing is wrong when it is wrong to kill."  "Lie" means merely "wrongful falsehood," so "Lying is wrong" translates "It is wrong to tell those falsehoods that it is wrong to tell."  "Promise" means only "vow it is wrong to break," so "Breaking promises is wrong" translates "It is wrong to break vows that it is wrong to break."  In each case, all that we are really being told is "It is wrong to do what it is wrong to do."  True, there is a rudimentary agreement across cultures that at least it is sometimes wrong to kill, to tell falsehoods, and to break vows.  But concerning the substance of the matter -- when it is wrong to do these things -- there is no agreement whatsoever.  The supposed universals turn out to be mere tautologies; they say literally nothing.

Now this is an empirical claim, and as such, it invites investigation.  Posner sees the invitation coming and heads it off by sheer assertion.  As he obviously knows, natural lawyers would say that discordancy among cultures about killing, telling falsehoods, and breaking vows conceals an underlying unity.  There exist certain universal norms -- discovered, not invented -- from which the codes of particular cultures may deviate in various ways, but to which they are better or worse approximations.  Though Posner asserts as a given that this is not true, it is not a given; it is precisely what we are trying to ascertain.  Are there in fact implicit norms to which the codes of particular cultures are better or worse approximations?

Stay tuned:  Continued tomorrow.