And there we come down to the root of the issue - you define marriage as "a state-sponsored contractual arrangement between (at the moment) two natural persons". I define marriage as "a union of a man and a woman that establishes a family and which precedes, in time and in causality, the state". As I said, only one of us can be correct.

If law is the application of rightly-ordered reason to the task of achieving the common good (as I hold) then the _nature_ of marriage determines and limits what kinds of benefits, advantages, limits, and restrictions the state may place upon people. If I'm right, then what marriage and family _is_ matters a lot (and where we should focus our discussion). If we only care about marriage as an act of power carried out by those with the most capability for force, then obviously this is all academic and whatever happens is whatever happens and why get hot under the collar about it?