Earlier this week, supporters of Proposition 8, the 2008 California marriage amendment, asked the U.S. Supreme Court to uphold the freedom of California voters to define marriage as one man and one woman in their state constitution.

This request comes at the same time that voters prepare to vote on marriage through ballot measures in four other states—Maryland, Maine, Minnesota, and Washington.

California voters passed Prop 8 in 2008 by a 52–48 percent margin, but same-sex marriage activists, unhappy with the result of the vote, asked a federal district court judge to strike down Prop 8 as a violation of the U.S. Constitution.

The federal district court judge complied, ruling that Prop 8 violates the U.S. Constitution and finding, among other things, that “the evidence shows beyond any doubt that parents’ genders are irrelevant to children’s developmental outcomes.”

The case then went to a three-judge panel of the U.S. Court of Appeals for the Ninth Circuit, which also ruled against Prop 8 by a vote of 2–1.

Until the Ninth Circuit’s panel decision, Prop 8 supporters assert, “every state and federal appellate court to consider a federal constitutional challenge to state laws defining marriage—including [the U.S. Supreme Court in the 1972 case of Baker v. Nelson]—had upheld the traditional definition [of marriage].”

Further, voters in 32 states—most recently in North Carolina in May—have voted to protect marriage as the union of husband and wife.

Yet some same-sex marriage activists continue to argue that there is no rational reason to defend marriage as one man and one woman.

Protecting marriage as one man and one woman is not irrational. It is one of the most rational things a society can do.

Marriage is society’s best means of ensuring that children will be born into intact families and raised by the mother and father who created them. Individuals marry based on various private interests. The public interest in marriage is based directly on the role that marriage plays in creating and raising the next generation.

Because of this essential connection between children and marriage, marriage is rightly described as “the cornerstone of the family” and family as the “basic building block of society.”

Society has good reasons to protect and promote marriage in the law.

Same-sex marriage denies the truth about marriage by breaking the essential connection between children and the mother and father who created them. Marital norms such as exclusiveness and permanence are related to the connection between marriage and children. Breaking that connection in the law will further weaken social commitments to these norms for marriage generally.

Same-sex marriage also puts the law on the wrong side of reality by claiming that marriage is something other than what marriage is: the union of husband and wife. Many kinds of relationships are meaningful and valuable to the individuals involved and even to the broader public. But that does not make them marriages. It is not irrational or bigoted for the law to recognize that marriage is a unique kind of relationship deserving a unique kind of status.

The marriage debate presents society with fundamentally different competing visions of what marriage is. This particular debate is best resolved through the give and take of political processes. In the Prop 8 case, the Supreme Court now has the opportunity to return the question of marriage to the people of California.