I have yet to finish reading Mulieris Dignitatem, but I have read the shorter recent CDF document on the Collaboration of Men and Women, which indirectly refers to the issue of "mutual subjection", as has been discussed in a recent post. The way I am reading it, the phrase "mutual subjection" in the former document seems to be used in the same context as "collaboration" in the latter. In fact, a case could probably be made that the expressions are interchangeable. Rome seems to have made a decision, more or less explicit, that since the phrase "mutual subjection" has a clear hierarchical implication, potentially conflicting at that, they have rather substituted the word "collaboration", which has a greater chance of being understood in the manner intended.
So, taking the word "collaboration" and projecting it backward onto Mulieris Dignitatem is a useful exercise. In fact, that document, as well as the comments others have made, become abundantly clearer, when understood in this way. When trying to force a new meaning onto an existing word, there is bound to be misunderstanding, as with the phrase "mutual subjection". As Scripture and many other sources make clear, to be "subject to" someone has an objectively hierarchical implication. No matter how frequently or forcefully it is repeated, it is simply incomprehensible how two people could be subject to each other in all things. It makes a mockery of the word "subjection", in the way it is normally understood.
Now, it is a different story when we talk about being subject to each other, where the wife is subject to the husband as head, and the husband is subject to the wife as heart of the family. It's a possibility that St. Paul's exhortations are meant to be understood in this way. However, it's hard to imagine marriage or family life being compartmentalized in such a manner. That's why I believe the Holy Father's statements and documents, when taken in the context of this particular interpretation of Ephesians 5:21, assume that mutual subjection is to be understood only in terms of collaboration.
We all know that Holy Scripture is not to be limited in its meanings, and the Holy Father has brought one meaning out of Ephesians 5:21. Personally, I would not have chosen to do it that way, but that's why he is Pope and I am not. I can see how he is using the concept of equality in dignity to make his point regarding the truth about humanity, and using Ephesians 5:21 to support that point. However, the Holy Father also rightly has not excluded other interpretations of Ephesians 5:21 in Mulieris Dignitatem or anywhere else. There must certainly be a grave reason to exclude a particular interpretation, such as if a particular teaching were being deformed or denied because of it.
As a case in point, consider the interpretation of Ephesians 5:21 that I have advanced. Specifically, that people need to allow themselves to be subject to others in authority, for the right ordering of society, whether that be a domestic society (the family), spiritual society (the Church), or civic society (the government). There are several other exhortations in the New Testament which support this view: servants being subject to masters (1 Pet 2:18), faithful to their bishops (Hebr 13:17), citizens to the governing powers (Tit 3:1). Note that this interpretation of Ephesians 5:21 does not contradict the interpretation of mutual subjection in terms of collaboration. It is an additional interpretation, at a different level of scope, which leaves completely intact those exhortations St. Paul gives to husbands and wives, that follow verse 21. My own preference is for this interpretation, since the other tends to eclipse the specific exhortations St. Paul gives to husbands and wives, and deflate them of their full significance.
In fact, we even find a parallel to St. Paul's exhortation of Ephesians 5:21 in one of St. Peter's letters: "Be ye subject therefore to every human creature for God's sake..." (1 Pet 2:13), whereas the two specific examples that follow refer to subjection to kings and governors, and there is no mention of married couples. Has either St. Paul or St. Peter ever urged a Christian governor to be subject to those under his charge? No, because to do so would be nonsensical. The Holy Apostles rather advocate meek submission where it is required for a justly ordered society, regardless what type of society is being mentioned. So, if there is any type of universal subjection among Christians, that must be the sort of collaboration with the will of God that the Holy Father is talking about, which is in addition to the right-ordering of hierarchical relationships urged by the Holy Apostles, one of which is very distinctly that wives ought to be subject to their husbands.
Clearly, the time in which we live is not opportune for proclaiming such a teaching, as is evidenced by the force with which it is denied, even in this forum. I believe this is why the Vatican has muted (i.e. toned down, but not contradicted) the traditional Church teaching on subjection, and has instead chosen to highlight the more fundamental, and easier to swallow, teaching on collaboration between spouses in particular (as described in Mulieris Dignitatem), and between all men and women in general (as described in Collaboration of Men and Women).
It is true that the last thing many men need is to be granted Church approval for relegating their wives to a life of servitude, demeaning everything they say, and denying even their very worth, which is likely how it has too often been interpreted in the past. But the day shall come, when people realize that the teachings of the hierarchical relationship of the family, as well as the hierarchical relationships in the Church, are necessary for the right ordering of humanity during this earthly life. To that end, men must take up the challenge to "...love your wives, as Christ also loved the church and delivered himself up for it..." The real challenge is to figure out how to do that, and put into practice everything that exhortation implies.
In my blog extreme catholic I bring back "Casti Connubii" of Pope Pius XI which has the language which makes feminists go crazy. You can see how much things have changed by comparing the documents over 75 years.
Maggie Gallagher has a fantastic column this week, on the dynamics between husband and wife, using the wit that only she can bring.