I just gave you reasons for why they ' re different and you ignored them . If you want to allow gay marriage because it ' s socially popular at the moment , just admit it . But don ' t hide behind the pretense of being objective or giving a shit about civil liberties . What you don ' t understand is we ' re talking about how to define marriage at a categorical level . Individual exceptions of infertile couples don ' t erase the justification for defining marriage a certain way and for what reasons . Otherwise , marriage would have NO definition . Is marriage about love ? Well some couples don ' t love each other . Is marriage about stability ? Well come couples are very unstable . Is marriage about focusing on long term planning ? Well some couples are impulsive . So using your standard of how to define marriage one that includes NO EXCEPTIONS marriage would be about nothing . In reality , the state defines marriage around all of these things and more because in general these are the things that result from marriage . Samesex marriage is different because categorically they don ' t create children . It would be like if there were somehow a group of people that were incapable of being stable or responsible in marriage . It would be reasonable to have a discussion about whether or not the state wants to spend resources on promoting that type of marriage .