[OldDeckHand]

"There are some things that the states can define inivdually, but there are some things the we need define as a nation; one single, common definition. Marraige is one of those things. "

And yet, states do define marriage. Again, some states allow 1st Cousins to marry, others do not. In your example, there is some universally understood definition of "marriage". Does you definition allow 1st Cousins to marry, or does it not?

[BenKenobi]

“And yet, states do define marriage. Again, some states allow 1st Cousins to marry, others do not. In your example, there is some universally understood definition of “marriage”. Does you definition allow 1st Cousins to marry, or does it not?’

They are permitted to determine the age of majority, are they not?

There’s a legal distinction between changing the particulars, (age, consanguinuity, and race), from the definition, (bigamy, polygamy, and homosexuality).

No state has ever, in the history of the United States been permitted by the federal government to endorse bigamy. Why?

[NurdlyPeon]

And yet, states do define marriage. Again, some states allow 1st Cousins to marry, others do not. In your example, there is some universally understood definition of "marriage". Does you definition allow 1st Cousins to marry, or does it not?

Allowing or not allowing cousins to get married is regulation, not definition. The definition of marrage is one man, one woman. As far as age, familial association, and race, those are details which are regulated. As far as the first cousin thing goes, if they are of a different sex, then it's a state issue. If they are of the same sex, it's a federal issue, because they do not fit the federal definition of marraige.