I ran across this video clip that appears to me to have been the most civil debate I have encountered on the definition of marriage. I found it over at First Thoughts . The current efforts in culture to deny the necessity of marriage being between a man and a woman, a relationship and open to life (future generations), and an exclusive bond, are really efforts founded on very weak arguments from sociological, anthropological, religious and philosophical points of view.
It is a lengthy clip (over 60 minutes) but I think you may find it worth your time and energy to view.
Let me know what you think.
Here is the link: http://bloggingheads.tv/videos/29404?in=00:00&out=61:00 This link will take you to http://blogginheads.tv.