Perhaps the most interesting and most controversial book on biblical interpretation published in the last ten years is William J. Webb's Slaves, Women & Homosexuals. The austere title signals to the reader three subjects that have been the most debated in the last 200 years. And for good reason: all who make up those people groups have been marginalized and oppressed under those who supposedly hold the authority of scripture.
Webb takes seriously the intuitions of the modern reader who is rightly appalled after reading a text like Exodus 21:20-21:
"If a man beats his male or female slave with a rod and the slave dies as a direct result, he must be punished, but he is not to be punished if the slave gets up after a day or two, since the slave is his property."
What to make of such a barbaric practice, which appears to be sanctioned by the Bible? Webb's answer: read it from the slave's point of view. At the time it was written, this was seen as having a softening effect on the institution of slavery; under the Mosaic Law, slaveholders could not go beyond certain limits, specifically causing the death of their slave. Unlike the surrounding culture, which put no limits on slaveholders, this text has a `redemptive component' that moves the culture towards a better ethic, one that ultimately vindicates the abolition of slavery. Thus, to read the `words on the page' in isolation from their redemptive spirit and ethical movement is to misunderstand the text.
This raises the question of cultural analysis: how to go about it? By what criteria do we discern the cultural components of a text from the transcultural ones? Webb proposes 18 different criteria meant to discriminate texts that address passing cultural conditions from those that are applicable in all times and places. As a result, he concludes that a "redemptive-movement" hermeneutic leads to the abolition of slavery and either egalitarian gender roles or what he calls "ultra-soft patriarchy" (symbolic male headship that is functionally egalitarian); but, he concludes, it does not lead to the blessing of covenantal same-sex relationships.
I leave it to the reader to explore the soundness of Webb's criteria, but I am less sanguine about his project than I used to be. While there is much I agree with regarding how his hermeneutic determines what the text is saying, why it says it, and where it is taking those who apply it, I think the categories of "cultural" and "transcultural" are too vague to be helpful. For example, when discussing how scientific evidence determines whether a text is "cultural" or "transcultural" he brings up the texts that appear to presume a geocentric view of the cosmos, and says, "the geocentric component of biblical cosmology is cultural..." This is an odd way of putting it. Wouldn't it be more accurate to say that the geocentric component of biblical cosmology is false?
I think so, and therein lies the problem. There are certain questions that are not best served by appeals to cultural relativity. Here a few that are relevant to the issues of slavery and female subordination:
 Is it ever morally permissible to own another human being?
 Is the following proposition coherent: `x is equal with y and x is designed to be subordinate to y?'
 Is a hierarchy that stipulates that person P is subordinate to person Q by virtue of P's being P a morally acceptable form of hierarchy?
Each answer demands a 'yes' or 'no' answer. Making a judgment either way is not determined by whether a text is culturally relative; rather, our judgments about these questions determine whether the texts in question are morally flawed or accommodating a morally flawed situation. Texts that address the topic of divorce are a good example. Begin by asking whether the Bible allows for the permissibility of divorce. If we say 'yes,' then we have to decide whether the text is morally flawed or accommodating morally flawed situations. If it is morally flawed, then we are judging it by a prior 'no-divorce' ethic. If it is accommodating morally flawed situations, we have to determine what those situations are and apply the text accordingly. If we say 'no, it doesn't permit divorce', then we have to explain why certain texts seem to allow for divorce (and how do you do that?).
As for slavery, either the Bible says it is morally permissible (under certain circumstances), or not; but we should recognize that much of its instructions address circumstances when slavery is a fact of life, and that we should act in such-and-such way if we are in those circumstances. Categories of truth or falsity, and moral permissibility or impermissibility are the relevant issues at stake--not whether things are "cultural" or "transcultural." (If it were, I would have expected a longer treatment of head coverings, but alas they went unaddressed.)
This is precisely what made the argument for abolition so difficult. The pro-slavery side could always say, "Look, if the circumstances are such that slavery is part of the economy, then these are the principles we have to abide by (submitting without complaint, not being harsh, ect)." This is the same problem that faces egalitarians: if women are uneducated or become utterly dependent on the physical labor of males, then the acceptability of female subordination in the home and church seems to follow. Yet Webb (rightly, I think) would advocate for abolition and egalitarian gender roles. But why? I assume it is because he thinks a more thoroughgoing biblical theology of the "ultimate ethic" he appeals to can be established. Unfortunately, he spends little time developing it. Of course, it isn't fair to expect this from a book devoted to developing criteria for cultural analysis, but his conclusions largely rest on some weighty background assumptions.
All this is not to say that Webb's hermeneutic and his 18 criteria are not useful and informative. There is a lot worth considering, and those who disagree with him have their work cut out for them in defending a "static" hermeneutic.