Oh yay! I was just about to challenge magellan01 myself since no one was trying to set forth those points. Yours are the points I’d try to challenge, but I don’t know how effective I’d be, so I’m glad you came back to reiterate them.
Here’s how I’d answer your objections: (these are my own answers; I’m not speaking for magellan01 who probably has his own ideas)
In speaking of the ideal, marriage could just be defined as a man, a woman and children (if any)–basically the basis of a nuclear family now.
In that way, the definition wouldn’t include two adults of the same gender.
As to rights, the meaning would be more consistent with benefits. So any benefit that derives from traditional marriage such as financial incentives or contractual rights could be conferred on gay couples.
Under that definition, 2 and 3 are consistent.
I’m not sure that one needs to endanger the foundation of society to find it undesirable.
How would polygamy endanger the foundation of society?
It may look ridiculous now; it probably didn’t then. And I’m certain that some things that people defend automatically without thinking now will seem outrageous in the future.
Given that, I thought this post by Miller in a thread in GD was very interesting:
How do we determine which traditions are positive and unifying and which ones are divisive? I’m thinking that I might be seeing those traditions in the opposite ways in which he sees them.
*if you want to see his comments in context, just hit the arrow next to his name and that should take you back to the thread.