Advocates of same-sex "marriage" are known to reach for one of the oldest arguments in the liberal arsenal - that a vote in favor of their point of view is a "smart" vote, and a vote against it is the mark of a knuckle-dragging reactionary.

Well, is it?

The question takes on added prominence as the House of Representatives prepares to vote Thursday on a constitutional amendment protect marriage as the institution of one man and one woman. Congress must pass the amendment before it can be considered by the states, where three-fourths of the nation's state legislatures would have to approve it before it became law.

So what is the smart vote? Well, as is the case any time we're considering big, important national questions, we have to answer that question with this one: What are the goals? When we think of what the American government's policy toward marriage should be, we need first to establish what it is we want that policy to encourage.

Let's say, for the sake of argument, that the goal of marriage policy is the same as the goal for most other policies - to make the lives of most Americans better. If that is the case, one need only check out what the research says about the significance of marriage. To get a quick snapshot, take a look at the new database from the Heritage Foundation on marriage and family issues.

Social-science experts here at Heritage have taken a long look at the research to date on various households, particularly the traditional family - one which consists of a man married to a woman and living with their children. And the data is overwhelming. It suggests that, at this fragile time in the history for families, for faith and for other forces for good in society, this is no time to experiment with the basic family form or with the institution of marriage.

Those in Europe, and on a limited basis elsewhere, who have undertaken such experiments, have found that granting same-sex partnerships the status of marriage is not strengthening the institution of marriage nor improving children's chances of growing up with a married mother and father. Either way, the Heritage research came at it from the other angle. What good comes from standing up for the traditional family? What makes it worth defending?

Let's remember our policy goals. The husbands in such families are happier, less likely to endure depression, healthier, wealthier and far more stable mentally. The wives are happier, healthier, wealthier and less likely to experience both depression and physical or mental abuse.

The children of such marriages - the future of our country - grow up to earn more, learn more, live healthier, more active, more outgoing, more happy lives than those in other family models. They are less likely to become depressed, to repeat a grade in school, to get in trouble with the law, alcohol or drugs or to fail in their own relationships. Stability begets stability.

And again, if the question is: Which decision - for the amendment or against the amendment to protect the institution of marriage - will produce the most happiness among Americans, let's consider all this data.

States are taking action to protect marriage in the meantime. In two states - Missouri and Louisiana - voters already have approved by huge margins ballot initiatives to protect marriage in their constitutions. Eleven more will consider the same question in November. One lesson we can learn from the abortion debate is that having the courts decide will lead neither to true resolution of the issue nor to consensus among the American people. Courts should not be issuing policy edicts like this. The people should speak - and they are doing so through their ballots.

I'm not telling the House how to vote on Thursday, though you can. But I am saying that my view - that marriage should be limited to the union of one man and one woman - doesn't make me a Neanderthal. And even if you think it does, what's the harm in letting the people - rather than courts that often come far from a.) reflecting our views and b.) doing what's best for America - decide?

Rebecca Hagelin is a vice president of the Heritage Foundation.