[You can watch video of this testimony here.]

I will be speaking today from the perspective of political science and philosophy to answer the question “What Is Marriage?” I’ve co-authored a book and an article in the Harvard Journal of Law and Public Policy with a classmate of mine from Princeton, Sherif Girgis, and with a professor of ours, Robert George. Justice Samuel Alito cited our book twice in his dissenting opinion in the Supreme Court case involving the Defense of Marriage Act.

The title of that book is “What Is Marriage?” An answer to that question is something we didn’t hear today from people on the other side. It’s interesting that we’ve had a three-hour conversation about marriage without much by way of answering that question.

Everyone in this room is in favor of marriage equality. We all want the law to treat all marriages equally. But the only way we can know whether any state law is treating marriages equally is if we know what a marriage is. Every state law will draw lines between what is a marriage and what isn’t a marriage. If those lines are to be drawn on principle, if those lines are to reflect the truth, we have to know what sort of relationship is marital, as contrasted with other forms of consenting adult relationships.

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So, in the time I have today, I’ll answer three questions: what is marriage, why does marriage matter for public policy, and what are the consequences of redefining marriage?

Marriage exists to unite a man and a woman as husband and wife to then be equipped to be mother and father to any children that that union produces. It’s based on the anthropological truth that men and women are distinct and complementary. It’s based on the biological fact that reproduction requires a man and a woman. It’s based on the sociological reality that children deserve a mother and a father.

Whenever a child is born, a mother will always be close by. That’s a fact of biology. The question for culture and the question for law is whether a father will be close by. And if so, for how long? Marriage is the institution that different cultures and societies across time and place developed to maximize the likelihood that that man would commit to that woman and then the two of them would take responsibility to raise that child.

Part of this is based on the reality that there’s no such thing as parenting in the abstract: there’s mothering, and there’s fathering. Men and women bring different gifts to the parenting enterprise. Rutgers sociologist Professor David Popenoe writes, “the burden of social science evidence supports the idea that gender-differentiated parenting is important for human development and the contribution of fathers to childrearing is unique and irreplaceable.” He then concludes:

We should disavow the notion that mommies can make good daddies, just as we should the popular notion that daddies can make good mommies. The two sexes are different to the core and each is necessary—culturally and biologically—for the optimal development of a human being.

This is why so many states continue to define marriage as the union of a man and a woman, many doing so by amending their constitutions.

So why does marriage matter for public policy? Perhaps there is no better way to analyze this than by looking to our own president, President Barack Obama. Allow me to quote him:

We know the statistics: that children who grow up without a father are five times more likely to live in poverty and commit crime, nine times more likely to drop out of school, and twenty times more likely to end up in prison. They are more likely to have behavioral problems or run away from home, or become teenage parents themselves. And the foundations of our community are weaker because of it.

There is a host of social science evidence. We go through the litany and cite the studies in our book, but President Obama sums it up pretty well. We’ve seen in the past fifty years, since the war on poverty began, that the family has collapsed. At one point in America, virtually every child was given the gift of a married mother and father. Today, 40 percent of all Americans, 50 percent of Hispanics, and 70 percent of African Americans are born to single moms—and the consequences for those children are quite serious.

The state’s interest in marriage is not that it cares about my love life, or your love life, or anyone’s love life just for the sake of romance. The state’s interest in marriage is ensuring that those kids have fathers who are involved in their lives.

But when this doesn’t happen, social costs run high. As the marriage culture collapses, child poverty rises. Crime rises. Social mobility decreases. And welfare spending—which bankrupts so many states and the federal government—takes off.

If you care about social justice and limited government, if you care about freedom and the poor, then you have to care about marriage. All of these ends are better served by having the state define marriage correctly rather than the state trying to pick up the pieces of a broken marriage culture. The state can encourage men and women to commit to each other and take responsibility for their children while leaving other consenting adults free to live and to love as they choose, all without redefining the fundamental institution of marriage.

On that note, we’ve heard concerns about hospital visitation rights (which the federal government has already addressed) and with inheritance laws. Every individual has those concerns. I am not married. When I get sick, I need somebody to visit me in the hospital. When I die, I need someone to inherit my wealth. That situation is not unique to a same-sex couple. That is a situation that matters for all of us. So we need not redefine marriage to craft policy that will serve all citizens.

Lastly, I’ll close with three ways in which redefining marriage will undermine the institution of marriage. We hear this question: “how does redefining marriage hurt you or your marriage?” I’ll just mention three in the remaining time that I have.

First, it fundamentally reorients the institution of marriage away from the needs of children toward the desires of adults. It no longer makes marriage about ensuring the type of family life that is ideal for kids; it makes it more about adult romance. If one of the biggest social problems we face right now in the United States is absentee dads, how will we insist that fathers are essential when the law redefines marriage to make fathers optional?

Much of the testimony we have heard today was special interest pleading from big business claiming that defining marriage as the union of a man and a woman would make it hard for them to appeal to the elite college graduates from the East and the West coasts. We heard no discussion about the common good of the citizens of Indiana—the children who need fathers involved in their lives. Redefining marriage will make it much harder for the law to teach that those fathers are essential.

Second, if you redefine marriage, so as to say that the male-female aspect is irrational and arbitrary, what principle for policy and for law will retain the other three historic components of marriage? In the United States, it’s always been a monogamous union, a sexually exclusive union, and a permanent union. We’ve already seen new words created to challenge each and every one of those items.

Throuple” is a three-person couple. New York Magazine reports about it. Here’s the question: if I were to sue and say that I demand marriage equality for my throuple, what principle would deny marriage equality to the throuple once you say that the male-female aspect of marriage is irrational and arbitrary? The way that we got to monogamy is that it’s one man and one woman who can unite in the type of action that can create new life and who can provide that new life with one mom and one dad. Once you say that the male-female aspect is irrational and arbitrary, you will have no principled reason to retain the number two.

Likewise, the term “wedlease” was introduced in the Washington Post in 2013. A wedlease is a play on the term wedlock. It’s for a temporary marriage. If marriage is primarily about adult romance, and romance can come, and it can go, why should the law presume it to be permanent? Why not issue expressly temporary marriage licenses?

And lastly, the term “monogamish.” Monogamish was introduced in the New York Times in 2011. The term suggests we should retain the number two, but that spouses should be free to have sexually open relationships. That it should be two people getting married, but they should be free to have sex outside of that marriage, provided there’s no coercion or deceit.

Now, whatever you think about group marriage, whatever you think about temporary marriage, whatever you think about sexually open marriage, as far as adults living and loving how they choose, think about the social consequences if that’s the future direction in which marriage redefinition would go. For every additional sexual partner a man has and the shorter-lived those relationships are, the greater the chances that a man creates children with multiple women without commitment either to those women or to those kids. It increases the likelihood of creating fragmented families, and then big government will step in to pick up the pieces with a host of welfare programs that truly drain the economic prospects of all of our states.

Finally, I’ll mention liberty concerns, religious liberty concerns in particular. After Massachusetts, Illinois, and Washington, DC, either passed a civil union law or redefined marriage, Christian adoption agencies were forced to stop serving some of the neediest children in America: orphans. These agencies said they had no problem with same-sex couples adopting from other agencies, but that they wanted to place the children in their care with a married mom and dad. They had a religious liberty interest, and they had social science evidence that suggests that children do best with a married mom and dad. And yet in all three jurisdictions, they were told they could not do that.

We’ve also seen in different jurisdictions instances of photographers, bakers, florists, and innkeepers, people acting in the commercial sphere, saying we don’t want to be coerced. And that’s what redefining marriage would do. Redefining marriage would say that every institution has to treat two people of the same sex as if they’re married, even if those institutions don’t believe that they’re married. So the coercion works in the exact opposite direction of what we have heard.

Everyone right now is free to live and to love how they want. Two people of the same sex can work for a business that will give them marriage benefits, if the business chooses to. They can go to a liberal house of worship and have a marriage ceremony, if the house of worship chooses to. What is at stake with redefining marriage is whether the law would now coerce others into treating a same-sex relationship as if it’s a marriage, even when doing so violates the conscience and rights of those individuals and those institutions.

So, for all of these reasons, this state and all states have an interest in preserving the definition of marriage as the union—permanent and exclusive—of one man and one woman.