Hmm, so this article seems to want to take a historical approach to marriage? Well I suppose we can be a little more historical, indeed a little more scientific, than the article was. Specifically, let us look at evolution.
I’m currently reading a book that might be of some interest: Man the Hunted. It takes a look at predation on human evolution. One curious tidbit that (so far) they mentioned but didn’t spend a lot of time on is the possibility that male cohabitation with other males is a somewhat recent evolutionary trait (around the time we moved into grassy planes, it would seem, so still pretty old) that developed to protect females and children. That might seem, on the surface, to support the idea that men are supposed to be the protectors of women. The oddity comes in how; the men in a group of our ancestors seem to have probably acted as decoys for predators. Populations that suffer a high predation rate can stand to lose a male much more readily than a female. Monogamous pairings, then, are to an extent a luxury; a people group has become stable enough and secure enough that the men don’t have to be expendable for the group to survive.
There is also some research (but, to my understanding, it does not yet approach the status of being definitive) that indicates human males are unusually inept at detecting children that aren’t theirs. It has been suggested that the human reaction to young is so broadly defined that it can even encompass non-human children (that is, random cute fluffy puppies, kittens, cubs, etc). Such a reaction would be evolutionarily advantageous where monogamy is not; in societies suffering from a high predation rate.
Curiously, the idea of a single male with a harem would actually be a bit of an evolutionary throwback. We might still classify a harem of one as a harem, if we define the term fairly loosely. Thus, male control of a single woman as a sexual partner is likewise an evolutionary throwback to a simpler, more brutal and savage time.
If the past may be used to defend a sexist perspective on marriage, then it may also be used to promote a liberal perspective on sex. If because marriage has traditionally been used to control sexual access to women it can continue as such, then an older, more traditional look would argue that restricted sexual access is an anomaly counterproductive to the survival of the group.
The problem, of course, is that just because something is very old does not mean that it is very good, particularly in the present day (thus, the concept f the argumentum ad antiquitam). Though being old doesn’t make something bad, either (argumentum ad novitatem). One must be willing to recognize the past and use it as a foundation for perceiving the future, but we aren’t chained to it. For example, traditionally, no one was allowed to vote. Curiously, not many conservatives arguing from tradition argue for that.
As a side note: since that article attempted to address gay marriage from an ultra conservative POV, this webcomic offers a fairly hilarious commentary on that sort of thing:
http://www.shortpacked.com/d/20090907.html... you can't tell me a perferated colon and a zillion times higher risk of contracting HIV is fun...
Don't forget incontinence.
Though it is fair to point out that this is not a sexual perfectly restricted to homosexual male couples.