PROVO — Same-sex marriage was the target of not-so-friendly fire on the last day of the Families Under Fire conference at Brigham Young University.

BYU philosophy professor Terry Warner on Tuesday took aim at the hot-button political issue, saying marriage between a man and a woman benefits couples and children — therefore, society as a whole — in a way same-sex unions cannot.

"It is madness to destroy the most venerable of our civilization's institutions just because a relative minority of intellectual faddists have taken to the notion that their social theory will work," he said.

Warner warned that the societal benefits of traditional marriage would disappear if marriage is extended to same-sex couples. Defenders of traditional marriage have not developed that idea successfully, he said.

"The arguments have got to make sense to a secular audience," said Warner, a member of The Church of Jesus Christ of Latter-day Saints, which sponsors BYU. "The scriptures and words of the prophets instruct and inspire us, but they aren't admissible on the secular battleground where the fighting is going on. I believe we need to bring into the debate aspects of marriage that don't ordinarily get mentioned."

For example, he said, men and women think and feel differently, which allows them to bring unique, complementary and irreplaceable contributions to their unions and their families.

Same-sex marriage, he said, "cannot possibly include the expectations and growth potential of traditional marriage, because those expectations and potential arise solely from the fundamental and complementary differences between man and woman."

Some evidence shows children also develop best in family structures that include traditional marriage, Warner said.

"Our culture is not likely to produce individuals who live altruistically, with expectations of personal sacrifice, domestic order, lifelong-fidelity, patience, inward security, modesty, sobriety and reverence if the traditional order of marriage disappears in the course of a few generations."

Warner, who earned master's and doctoral degrees at Yale University, is the latest in a line of BYU professors to speak out against same-sex marriage, including law professors Richard Wilkins and Monte Stewart. Like them, he specifically urged conferencegoers to vote for Amendment 3, which would change Utah's constitution to ban same-sex marriage.

Many at the conference hailed him for providing what they believed were helpful arguments against those lobbying for same-sex marriage.