But I think the point at which Odious's arguments and mine pass each other in the night is the issue of to what first principles are applied. For when I say that I don't believe law can be derived from first principles, I mean that I don't think one can start with a sensible postulate, apply sound deductive reasoning and arrive at any particular section of the United States Code, or even of the Constitution, nor even an approximation thereof. Odious, if I understand, professes to take issue with the notion that there are no principles underlying laws, because people do not enact laws based solely on the tautology that whatever the majority dictates is right--they account for them with notions of justice and God's will. In saying this, Odious already assumes that the ultimate arbiter of laws is the masses--either because they cause the law to be enacted, or because they refuse to obey it if it is not good.
I did say that men wouldn't obey bad laws, which indicates that law does depend on something exterior to itself, I'm not claiming that the masses are the final arbiters of lawfulness. Instead I would view the refusal to obey law as empirical evidence of an ideal problem--just as an individual law may be an expression of an ideal.
The above is, by the way, a statement with which I agree quite completely. I think that there are numerous ways of proceeding from a first principle to its empirical substance. The removal of a hand and the restriction of liberty as punishment for theft are rather different in character, but they're both laws regarding property, and both stem from the same form ("That's mine. If you want one, go get your own.") It would certainly be impossible to move directly from that first principle to the form it took in law while ignoring the accidents of history and culture, but it also seems fairly easy to trace the process backwards. We're in heated agreement!
Any attempt to construct an entire code of law based on an expressed abstract principle would be absurd at best, and tragic at worst. But simply because of the failure to express such a principle doesn't mean that it doesn't exist behind the laws. If I were still a Kantian, I'd call it an ideal--something which is coherent in itself, but too big for reason. Things like beauty, truth, freedom. Not that I am advocating attempting to base laws on such ideas. I have occasionally read history, and seen what happens when people decide to start all over. Cartesian philosophy, Lutheranism, and Platonopolis all come to mind.
Indeed, I think that the 'organic' way that law grows is the only way to achieve any closeness to the ideal whence it springs. Since the ideal is too large to be comprehended fully (although we generally know it when we see it), anyone claiming to understand it fully (Mr. Marx? Paging Mr. Marx! Also Mr. Hegel!) is clearly talking nonsense. The slow process of growth and judicious pruning is the best way to get near what we actually meant when we passed these stupid laws. Experience, and the decision of generations, over the logic of a few who happen to be alive: yes, please.
As a side note, we could probably stand a little pruning right now. I think a return to the Icelandic custom of reciting all the laws at the Thing, and removing those that aren't remembered, is an excellent one. The Islamic custom of memorizing every law might help as well.
I agree with your statement that civil law is 'the most fundamental example of law, and criminal law...a more recent anomaly.' However, the reason for this seems to me that civil interactions are rather more complex than criminal ones. Criminal interactions, until recently, were dealt with by the person being threatened, and were, one way or the other, over with quickly. We do see in certain historical codes that when societies which had been used to frontier justice gathered together, that they promptly developed an intricate code for dealing with crime, as a means of preventing social chaos from endless retaliations. These codes arose only when the primitive method of crime-prevention was no longer compatible with civilization. But the case for derivation from fundamental principles is clearer here, although as Proclus points out, you're still not likely to 'start with a sensible postulate, apply sound deductive reasoning and arrive at any particular section of the United States Code'.
So we agree, as far as I can tell, except that you, as suits your education, stress the fact that any attempt to base laws on the justness of their effects will fail, and I, as suits my education (or lack), stress the fact that nevertheless we are constantly attempting to approach that ideal. I do stand by my statement that law is not simply a dispute-resolution mechanism, accepted somewhat at hazard by civilizations. But that's a little more meta than we need to get. Moreover, as I think is clear above, I don't think that analytically hollow ideas are necessarily motivated by emotion. Certain things emerge from contemplation rather than calculation.