Today, when the issue of same-sex marriage is discussed in the courts, academy, media and public square, the debate is usually framed in terms of “marriage equality.” But as many have pointed out, including Justice Samuel Alito in his United States v. Windsor dissent, such rhetoric belies a deeper, underlying debate: the question of what marriage actually is.

From this perspective, Columbia editor Alton Pelowski recently interviewed Ryan T. Anderson, a fellow at the Heritage Foundation in Washington, D.C., and founder and editor of Public Discourse, the online journal of the Witherspoon Institute in Princeton, N.J. Anderson is co-author, with Sherif Gergis and Robert P. George, of What is Marriage? Man and Woman: A Defense (Encounter Books, 2012).

Columbia: You point out that in the marriage debate today, there are two fundamentally different understandings of marriage. How do these views differ?

Ryan Anderson: As Justice Alito helpfully explained, there’s the conjugal conception of marriage and then there’s the consent-based, or revisionist, view of marriage. In the consent-based view, marriage is simply an intense, loving relationship between consenting adults. It is gender blind and not based on the sexual differences between man and woman.

Our account of marriage, the conjugal account, is that marriage unites a man and a woman to be mother and father to any children that they conceive. It’s based on a more comprehensive union — a union of hearts and minds, but also a union of bodies. What’s significant here is that the act that unites a man and a woman is the same act that creates new life.

Marriage needs to be sexually exclusive because this type of relationship can produce new life. It needs to be a permanent because it’s a comprehensive union and because children need a stable environment with a mother and father. With the revisionist view, on the other hand, there’s no real justification as to why it should be between only two people, exclusive or permanent.

For the state, neutrality on this question is really impossible. The law will enshrine one vision of marriage or another, and no matter what, one vision of the good, the true and the beautiful will be advanced. So the question is, which vision is the true vision? We want to get law reflecting reality as much as possible.

Columbia: How does the issue of equality relate to the definition of marriage?

Ryan Anderson: In some sense, everyone in the debate is in favor of equality. We all want the government to allow people to enter marriages equally. The question, then, is what is marriage? Only if we know what marriage is can we know if the law is treating marriages and spouses equally or not.

Every marriage policy will draw a line between what is and what isn’t a marriage. The revisionist account of marriage is no different; it draws a line at the number two. But if equality demands redefining marriage to include the same-sex couple, then does equality demand redefining marriage to include a three-person relationship? This is an open question in some people’s minds. The government needs to justify why it recognizes a certain type of relationship as marriage and not others.

Columbia: Why does the state have an interest in regulating marriage in the first place?

Ryan Anderson: Government is not in the marriage business because it cares about the love lives of consenting adults, apart from the fact that a certain type of loving relationship produces children. So the issue here is the government’s interest in ensuring that every child’s right to a mother and father is protected in the least coercive and least intrusive way possible.

Instead of encouraging a mother and father to raise their children as husband and wife, the government could try to raise children themselves, as with Plato’s thought experiment in The Republic. But with the breakdown of marriage in recent decades, we’ve seen how the welfare state has grown with disastrous results for children. We have seen an increase in crime, prison population and child poverty, and a decrease in social mobility.

Social justice and freedom are better served by the government getting marriage right, so that civil society can do the work that government can’t. When the marriage culture falls apart, we are left with a big government welfare program to pick up the pieces.

Columbia: What about the case of infertile couples and the fact that even heterosexual couples today dissociate marriage from procreation?

Ryan Anderson: No one has ever thought that every marriage will produce a child. We’ve never had fertility requirements in marriage law. But everyone knew that every child was the result of a male-female union. Marriage laws and policies maximize the likelihood that a child will grow up to know the love and care of a mother and father.

Public policy is based on the rule rather than the exception to the rule. The government’s interest is mainly in all of the marriages that will produce children and in male-female relationships that will produce children but are not yet marriages.

The question before us is this: Do we want to make marriage reforms that encourage marriage between husbands and wives, mothers and fathers, or do we want to double down on the idea that marriage is really just about adult desires?

Columbia: What is at stake? What effect could legally changing the definition of marriage have?

Ryan Anderson: First of all, redefining marriage makes it all about the desires of adults and eliminates from law and public policy any institution that upholds the ideal that a child deserves a mother and a father.

Secondly, the redefinition of marriage won’t stop here. If we reduce marriage to be just about someone you love, and see the male-female aspect as irrational or arbitrary, what’s magical about the number two?

The principled reason for why marriage is understood to be monogamous, sexually exclusive and permanent is precisely based on the male-female dimension. Apart from that, various scholars and activists have argued that marriage should just be about a contract between consenting adults. There’s no reason, they say, that it couldn’t be a temporary contract that can be renewed. Likewise, you see people saying that monogamy is unnatural and that extramarital affairs should be allowed, provided there’s no deceit or coercion.

Such proposals are a nightmare for the public policy interest, which is to get men and women to commit to each other permanently and exclusively. A greater number of sexual partners and short-lived relationships brings a greater chance of fatherless children and fragmented families.

The third consequence of redefining marriage relates to religious liberty. We’ve already seen Catholic Charities forced out of the adoption services that they have provided in places like Massachusetts, Illinois and Washington, D.C., because they wanted to place the children in their care in homes with a mom and dad. We have also seen florists, bakers, photographers and innkeepers who have been sued for refusing to participate in same-sex weddings.

Columbia: Why do you think that public opinion has swayed in support of same-sex marriage in recent years?

Ryan Anderson: We haven’t been making the argument. It’s not surprising that one side has more influence when it is well-organized, well-funded and very outspoken, while the other side is largely silent.

It’s also the fact that the past 40 years have been a nightmare for marriage in general. Same-sex marriage is only plausible in a world that has already done so much damage to marriage and human sexuality. The elimination of the male-female aspect of marriage follows the sexual revolution’s train of bad consequences: pornography, non-marital sex, extramarital sex, non-marital childbearing, divorce and so on. Young people don’t hear arguments in favor of the conjugal view of marriage, and they haven’t seen it lived out.

Columbia: How do you respond to those who dismiss the conjugal view of marriage as arbitrary and irrational, in part because it is associated with religion?

Ryan Anderson: Religious people also have views about things like murder and property rights. The question is whether or not the view itself commands rational support.

Consider all of the great thinkers who have considered the question of marriage: ancient Greeks and Romans; leaders of Judaism, Christianity and Islam; Enlightenment thinkers like Emmanuel Kant and John Locke; Eastern thinkers like Mahatma Gandhi. These thinkers disagree about so much in their philosophies, theologies and political theories, but they all agree that marriage is a male-female institution. It wasn’t until the year 2000 that any political community on the face of the earth defined marriage as anything other than a male-female relationship.

To say that the conjugal view of marriage is somehow irrational and arbitrary belies history and the reasoned arguments that support it.

Columbia: How do you recommend that people who hold the conjugal view of marriage relate to homosexual persons?

Ryan Anderson: I think this is the big question going forward, and it’s something that younger generations have to wrestle with in a way that previous generations have not. How do we show love and respect to our gay and lesbian friends, family members, and fellow citizens without redefining marriage? One cannot deny that over the course of American history gays and lesbians have been mistreated and abused in various ways — but marriage law is not one of those ways.

We need to find an appealing way of presenting the truth of marriage to our gay friends and family members, while affirming real opportunities for meaningful relationships and human flourishing. In previous times and cultures, people better understood close, healthy friendships; they did not seek emotional fulfillment only through marriage. Recognizing the uniqueness of marriage opens up broad horizons of possibility for deep relationships that are non-marital.

Columbia: What role can Knights of Columbus and other concerned citizens of good will play in preserving and promoting marriage in society?

Ryan Anderson: The first thing that they can do is live out the truth about marriage and human sexuality in their own families. Be faithful husbands and faithful wives. Be good mothers and good fathers. Young people, live out the virtue of chastity and prepare yourself now for your future marriage. Long before the debate we are facing today, marriage was falling apart because heterosexuals bought into a false, liberal ideology about sex.

The second thing is to work to protect religious liberty with regard to marriage law. We must make sure our elected officials and fellow citizens respect institutions and individuals who believe that marriage is between a man and a woman.

The third thing is to work now at making the case for marriage with increased vigor and commitment. We need arguments in social media, entertainment and broader culture — in as many different ways possible — that explain what marriage is and why it matters.