>Makes sense to me as does Charles original post. But does pose a question... if "state" marriage is simply a contract, why cannot that contract involve more than two consenting adults?

would lower the inheritance tax bracket and / or returns, at least over here ;-)
Pensions over here sometimes were awarded to surviving spouse, imagine hordes of potential suvivors.
Rules for funds breakup and support could become *much* more difficult in divorce hearings.
In therory I agree with all of the preposters and would add that most of tax benefits for married people should be given according to the number of kids cared for, with some spillover for time without a job history due to kids. Also some risk loss compensation, as gov has not to provide social security funds as long as one partner earns enough.

But arguing such stuff might spill over into religion as well. Having read about forced marriage / very young brides in some poly-setups makes gut twitch for fear of helping the wrong side - seems some biblical arguing US citizens are close to some found in areas Bill wants to nuke.