The ongoing debates over the legalization of “homosexual marriage” inevitably lead to a very basic question: Does marriage require a man and a woman?

It would seem to be an easy question. The Second Vatican Council speaks of marriage as a “whole manner and communion of life” which includes both mutual love and openness to new life (Gaudium et Spes, 51).

Part III

Since procreation requires a man and a woman, this teaching has an obvious application to the question of “homosexual marriage.”

On Jan. 21, in an address to the Roman Rota, Pope John Paul II stated that homosexual unions cannot be marriages “above all because of the objective impossibility of being fruitful in the transmission of life, according to the plan inscribed by God in the very structure of the human being.” (The Rota is the Holy See's ordinary court of appeals especially known for handling cases involving the validity of marriages.)

The Holy Father added that homosexual unions could not be “marriages” because “there is an absence of those interpersonal complementary dimensions which the Creator willed.”

While this teaching on marriage is natural enough within the Church, it faces a tougher audience in the rough-and-tumble of public debate in America today. Below are three arguments offered by supporters of “homosexual marriage,” and the counterarguments that Catholics could offer.

1) ‘Marriage is just a convention’

This argument says that “marriage” is simply something made up by society. Because there is no enduring truth about marriage, the argument goes, a society is free to legally redefine it.

This argument makes a big assumption: that marriage is just a convention. There are, of course, aspects of marriage and marriage law that vary from culture to culture. But in response, it can be noted that in every society there are men and women, different yet designed for one another. In every culture, these opposite-sex couples come together and form families.

2) ‘Marriage is a right’

The second argument says that because each citizen has a constitutional right to marry, to exclude homosexuals from legal marriage violates the Constitution.

This argument begs the question, however. If marriage is whatever society says it is, then presumably anybody can marry anybody. But if marriage by definition requires a man and a woman, two homosexuals cannot marry, and no homosexual is “excluded” from marriage.

The right to marry is not the same thing as redefining marriage in order to have a right to it.

3) ‘Marriage will help homosexuals’

The third argument is that marriage would reduce promiscuity among homosexuals. This argument assumes that “marriage” is just a tool of social engineering.

The issue of promiscuity among homosexuals and heterosexuals is a serious one. But marriage is an institution that requires a man and a woman, it is not simply a “policy” that government can “reform” in order to solve social problems.

These arguments in favor of “homosexual marriage” share the view that there is no transcendent truth about marriage, other than vague appeals to “love” and “commitment.” By contrast, the arguments in favor of heterosexual marriage acknowledge that there is a truth that transcends mankind.

Indeed, this is the real divide between those who support or oppose “homosexual marriage.” It is not first of all a disagreement about the morality homosexuality. It is a difference about the existence of truth.

Perhaps that explains why elected officials have consistently reaffirmed marriage. They recognize that an understanding among people of what marriage really is. They also understand that to tinker with that definition is to invite disaster, socially and politically. Congress passed the Defense of Marriage Act overwhelmingly, and in every state but one that has passed a marriage recognition law, the margin of support has been higher than 70%.

Catholics who agree that the word “marriage” means something enduring share with their fellow citizens some basic, obvious, and yet now vigorously disputed assumptions.

They assume that men and women are equal, yet biologically and psychologically different. They assume that these differences complement each other in important ways.

They assume that together, men and women form a unique community, and that one of the central tasks of this community is having and raising children.

They assume that this community called “marriage” is indispensable to a healthy society.

They assume that any attempt to “redefine” marriage by law is absurd; tyrannical, because it will bypass the democratic process if done solely in the courts; and unwise, because it will create a state-sanctioned message that all sexual relationships are morally and legally equivalent.

Citizens who agree with these assumptions may find that the best time to influence the ongoing debate is now. How they can do so, will be the topic of the next and final installment of this series.

David Coolidge writes from Washington, D.C.