Theory of Halachic change

Zachary Sholem Berger recently made a comment that I feel compeled to respond to.   In the context of a post on Orthodoxy and Homosexuality he said:

Here I need to admit something ("Today I admit my sins"!). I've never seen a logically consistent exposition of the Orthodox philosophy of halachic change. Maybe I'm ignorant (which is likely), but another possibility is that much of Orthodox resistance to halachic change has to do with a general conservatism rather than a hewing to a set of halachic axioms. (If you show me Rambam's laws of halachic judgment, please tell me how they correspond to today's methods of Orthodox jurisprudence.) There is nothing wrong with this: small-c conservatism is a necessary thing within every religious movement. But such conservatism does not imply an axiomatic consistency. It is this which I think Orthodoxy lacks, no matter how loudly its academicians do protest.

I think he misses the point here. Or more precisely, he gets the point exactly, while missing its ultimate significance.  The lack of a consistant Orthodox theory of halachic change is a symptom of the fact that the historiography of halacha is fundementally ahistorical.  What I mean is, so far as most of the Orthodox world is concerned, Avraham Avinu more or less kept the same Halachot that we do now, and whatever differences there are between his practice and ours disappeared at the time of the Revealation at Sinai.  When Berger says that "Orthodox resistance to halachic change has to do with a general conservatism rather than a hewing to a set of halachic axioms," he isn't entirely wrong, but he isn't entirely right either.  It isn't a simple viceral conservatism that keeps Orthodoxy from changing.  It's that Orthodoxy believes that every detail of the Halacha was revealed to Moses at Sinai.  All we do when we make new P'sak is attempt to apply what we know about Revealation to a new reality.
 
Now, this is a problem, because Halacha has changed over the course of history, which is the reason that many Orthodox Jews feel compelled to form a philosophy of change in Halacha.  I don't think it's really possible, given the current state of Orthodox theology, at least not a prescriptive theory.  At best we can come up with some kind of descriptive theory of how the Halacha developed in different historical periods.  It would not have the kind of "axiomatic consistancy" that Berger craves, but it might be useful to us, the Orthodox community, as presenting ways to approach the adjudication of future Halachic issues.