UPDATE: This entire debate is now available to download and watch or listen to on the ABC website here.

Arriving at the City Recital Hall in central Sydney last night, I was struck by the amazing turnout. Barely a seat was left empty on the floor and there were lots of expectant faces peering down from the mezzanine rows too.

This debate, part of the Intelligence Squared series run by the St James Ethics Centre, saw four speakers address the statement: Same-sex marriage should not be legalised.

As they walked in, every audience member was asked whether they agreed with the premise or not. I wasn’t surprised to notice a flurry of ticks in the NO column and only a few marking YES as I also voiced by dissent.

Speaking in favour of the motion were two very different academics – Professor Nick Tonti-Filippini, the Associate Dean and head of Bio-Ethics at the John Paul II Institute for Marriage and Family; and University of Sydney ‘Queer Theory’ researcher Professor Annamarie Jagose. Sydney’s very–rainbow-friendly Lord Mayor Clover Moore was there to rebut, along with opinion pollster and former political adviser Mark Textor.

“Marriage equality will be legalised – it’s just a matter of when.”

Opening his argument, Tonti-Filippini was at pains to assure his wary audience he was not homophobic. “I have friends and family who are gay,” he insisted. “Wherever there is true love, God is present!”

Homosexual marriage cannot be countenanced, however, as it would result in a huge change to what marriage means. Matrimony is all about the children, about creating new life, and it takes a man and a woman to do that, he asserted. There are too many absent fathers already, and we don’t want a situation were a same-sex couple can deny their child’s biological father or mother exists. The staunch Catholic even went as far as to say “We are in danger of creating another stolen generation,” prompting several audible hisses from the audience.

Clover Moore was next to speak, and was in fine form with a well-worn topic for her. “I strongly believe same-sex couples should have the same rights as opposite sex couples. Marriage equality will be legalised – it’s just a matter of when.”

Gays and lesbians do have loving, long-term relationships, she added, in a speech also referencing Barack Obama’s recent support of marriage equality, along with Penny Wong’s watershed moment on Q&A recently defending her family.

“For children in same-sex parent headed families, marriage ensures both their parents are with them,” she concluded. “This is not a threat to traditional marriage – it will strengthen it. Symbolically, marriage equality is essential… our law should be about inclusion, not exclusion.”

Professor Jagose proved to be another articulate speaker. The pro-gay academic’s view is that same-sex marriage is a ‘red herring’ on the road to social acceptance. Just because the tide is slowly turning in public acceptance to marriage equality, why should be want it? With a decline in marriage rates and an increase on divorces, the institution has fallen on hard times – perhaps marriage needs gays to revive it more than gays need marriage to feel equal?

Whereas LGBT people may well be able to teach straights a thing or two about sexual diversity, the marriage equality debate is turning us into sexual conformists, she argued. “Marriage equality comes at a cost – it continues to disavow some relationships.” What about singles, one-night-standers, those in open or polyamourous relationships? “Why should marriage raise the worth of some relationships and not others?”

Gays and lesbians often speak about the importance of diversity, but aiming to get married is not about diversity at all, concludes Jagose. “It is about being identical to heterosexual married people but differing in only one respect – the gender of one of the spouses. I call that conformity.”