"The single largest non-economic benefit that marriage affords is the right not to be compelled to testify against your spouse"
Try telling that to the person who can't visit their partner ,of 17 years, who's dying of cancer because they are not "next of kin".
"You can't have it both ways. On the one hand you say society has the right to restrict one form of marriage (between cousins, or siblings, or parent and child), but it does not have the authority to restrict another form of marriage (same sex). Either it does or it doesn't. You may not like how it restricts marriage, but that doesn't mean it doesn't have the authority to do so."
I never said society has the right to restrict certain marriages. I only tried to illustrate that you can't compare the two. By the way I did a little research and discovered that in AK, AL, CA, CO, CT, FL, GA, HI, MD, MA, NJ, NM, NY, NC, RI, SC, TN, TX, VT, VA and Washington DC first cousins are able to marry legally.
"Once again, if we say society does not have the authority to restrict same sex marriage, then how can an argument be made that would restrict marriage between a 12 year and a 25 year old, or an 8 year and a 40 year old."
The same arguments that restrict 12 and 8 year olds from driving. Sure society also has the authority to restrict others from driving, those that are intoxicated, those with impaired vision and those with evidence of previous reckless driving. However, these situations the person behind the wheel is viewed as a danger to others and there is sufficient evidence to prove that individuals driving under these conditions have caused significant harm to others as well as themselves.
"It should not be decided by 4 judges in Mass, or 4 county commishioners in Portland Oregon, or by the Mayor of San Fransisco. Allowing the people of each society to make those decisions is the nature of democracy."
Admittedly I'm wasn't a history major but I am unaware of any instance in this country where the citizens were charged with deciding whether or not rights would be extended to other citizens.