i found this at freepville. it's thomas sowell. he is a 'rational' person and if you want the "intellectual" opposition, this is as good as it gets. if you really want insight into the opposition, the article is a good read.
http://www.jewishworldreview.com/cols/sowell.htmlsnipo
If you only want to accept particular unlawful acts that you agree with, then of course others will have other unlawful acts that they agree with. Considering how many different groups have how many different sets of values, that road leads to anarchy. Have we not seen enough anarchy in Haiti, Rwanda and other places to know not to go there?
The last refuge of the gay marriage advocates is that this is an issue of equal rights. But marriage is not an individual right. Otherwise, why limit marriage to unions of two people instead of three or four or five? Why limit it to adult humans, if some want to be united with others of various ages, sexes and species?
Marriage is a social contract because the issues involved go beyond the particular individuals. Unions of a man and a woman produce the future generations on whom the fate of the whole society depends. Society has something to say about that.
Even at the individual level, men and women have different circumstances, if only from the fact that women have babies and men do not. These and other asymmetries in the positions of women and men justify long-term legal arrangements to enable society to keep this asymmetrical relationship viable — for society's sake.
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