Columnist Mona Charen: "If what 'matters' is that adults treat one another with respect, etc., what is the principled case against polyamory once same-sex marriage has become legally enshrined? What is the principled basis for objection? ... Personal happiness and fulfillment are frequent benefits of marriage, but they are not its purpose. Marriage is the institution that provides social stability because it attempts to ensure, insofar as possible, that the mother and father who create a new life commit to caring for that child until adulthood. No other adult arrangement has ever been shown to benefit children as much. To enshrine gay marriage is to say that two mothers, or two fathers are just as good for children as a mother and a father. And if sexual complementarity is dispensable, by what logic are the other aspects of traditional marriage -- exclusivity and permanence -- to be maintained? It's indisputable that traditional marriage was in crisis before the gay marriage movement began. The behavior of heterosexuals accomplished that. But ... the gay marriage movement had done a different kind of damage by undermining our understanding of what marriage is."