yeahbutt, this is where Roy Bhaskar's work on critical realism is helpful. He addresses the over-determinism of Berger and Luckman's social constructionism. If I recall correctly, he argues that such an approach is *merely* dialectical and advance an ahistorical approach to social change -- because too one-sidedly deterministic. A Critical Realism accounts for the interaction between social structural forces creating moral principles and then the small scale social practices people engage in that feed back into those moral pricniples, but not in any one-to-one pointer-reader way. People *make* history but not in any way they please, as the Old Man said.
too lazy to retrieve the book and summarize it properly but I think I've finally figured out why, while I agree with you in this debate, there's always a point where I pull back from the super-structuralism that statement seems to advance, if only by virtue of the typical DSM-IV 302.9 that goes on during this eternal debate. :)
shag