Next month, the U.S. Supreme Court is set to hear oral arguments for two closely watched marriage cases dealing with the constitutionality of the Defense of Marriage Act (DOMA) and California’s Proposition 8.

Few legal experts will predict the likely outcome of either case, but the oral arguments are expected — if only briefly — to air opposing views on the meaning and purpose of marriage.

Is it an institution uniquely devoted to the procreation and education of children or a "committed, lifelong relationship," as one federal judge described it?

At present, most advocates of "marriage equality" frame their position as an effort to expand the benefits of marriage to a previously excluded group of people, and nothing more. President Barack Obama, in his 2013 inaugural address, echoed this claim when he endorsed additional rights for homosexual persons and asserted that "the love we commit to one another must be equal as well."

Meanwhile, one allegedly "conservative" argument for changing the nation’s marriage laws posits that matrimony will provide an antidote to the social pathologies associated with the "homosexual lifestyle" — a suggestion that also presents marriage as a one-size-fits-all relationship with no distinctive grounding in the mission of procreation.

In 2010, when Judge Vaughn Walker ruled that Proposition 8 violated same-sex couples’ constitutional right to due process and equal protection, he concluded that the state had no rational basis or vested interest in barring same-sex couples from obtaining marriage licenses.

"Conjecture, speculation and fears are not enough," stated Walker in a decision that explained his reasons for setting aside the will of California voters. "Still less will the moral disapprobation of a group or class of citizens suffice, no matter how large the majority that shares that view. The evidence demonstrated beyond serious reckoning that Proposition 8 finds support only in such disapproval. As such, Proposition 8 is beyond the constitutional reach of the voters or their representatives."

Walker’s decision was appealed to the Ninth Circuit Court of Appeals, which issued a narrow ruling that backed the lower court’s decision.

On Jan. 29, the U.S. Conference of Catholic Bishops filed amicus briefs in support of DOMA and Proposition 8. Both briefs cautioned that any change in the nation’s marriage laws posed a direct threat to the free exercise of religion, among other issues.

But the brief filed in the Proposition 8 case, Hollingsworth v. Perry, also tackled Judge Walker’s assertion that opposition to same-sex "marriage" arose from unreasonable animus toward a minority group.

The USCCB brief countered that the "state may reasonably support and encourage marriage, understood as the union of one man and one woman, as distinguished from other relationships."

Catholic leaders and others who have resisted changes in the nation’s marriage laws have warned that if marriage is infinitely malleable — if it can be "anything" — then it is "nothing."

While the nation’s high divorce rate and a steep rise in non-marital births confirm that traditional marriage is in tough shape, the U.S. bishops’ Prop. 8 brief reminds the high court that marriage still matters, and it should be defended, not deconstructed.

"No other institution joins together persons with the natural ability to have children, to assure that those children are properly cared for. No other institution ensures that children will at least have the opportunity of being raised by their mother and father together," states the brief. "Societal ills that flow from the dissolution of marriage and family would not be addressed — indeed, they would only be aggravated — were the government to fail to reinforce the union of one man and one woman with the unique encouragement and support it deserves."

It is a testament to the moral incoherence of our times that the outcome of both marriages cases is by no means certain. Indeed, while a child’s need for a mother and father has long been viewed as the best argument for resisting changes to U.S. marriage laws, four separate victories for "marriage equality" forces during the 2012 election year indicate that we are in the middle of a sea change in public opinion.

The shift heralds the steady rise of individualistic norms that resist commonsense truths. And if the high court makes same-sex "marriage" the law of the land, that ruling is unlikely to assuage the demand for further accommodation to individual desires.

Can a nation survive when its courts, political leaders and citizens no longer agree on a child’s right to be raised by a mother and a father — or can no longer defend a once-established requirement for human flourishing?

When Church leaders defend that right, they are often accused of imposing their "religious views" on the rest of society. The Church and its allies reject that claim, noting that diverse cultures across the world uphold traditional marriage.

Rather, the Church asks a restless nation to pause and consider that marriage cannot be viewed in isolation of the common good, and it cannot be redefined without wrecking immense damage.

In the journal First Things, George Weigel warns that the battle over marriage marks an era of growing political instability.

"The marriage debate is thus about more than the legal definition of marriage, although that is serious enough," writes Weigel. "It’s a debate about whether there are any givens in the human condition or whether willfulness and self-assertion trump reality at every point. If they do, what happens to democracies built on self-evident truths?"