Today, the High Court is hearing arguments about the same-sex marriage plebisurveythingummy, which, in the opinion of constitutional guru George Williams, is likely to be struck down. But while the silks slug it out, what better time to look at the arguments that have been playing out in the public space?

The curious thing about the No campaign is that the arguments advanced rarely have much to do with the central question of whether two people of the same sex should be allowed to enter a secular marriage.

So let's take a look at some of the things the No campaign has been talking about instead of the question being posed in the ABS one-question questionnaire — "should the law be changed to allow same-sex couples to marry?"

1. When a man loves a bridge

A slippery slope argument is when you argue that allowing one thing will inexorably lead to a far worse thing. Eric Abetz suggested that marriage equality could subsequently lead to people marrying the Harbour Bridge because "why not?" And full credit to him — I've never previously seen a slippery slope argument involving an actual slope.

Senator Eric Abetz offered a slippery slope argument that actually involved a slope. ( AAP: Lukas Coch )

But let's answer his question. Bridges, at least as far as I know, are not sentient beings able to consent to marriage. Besides, last time I checked, the Harbour Bridge was very much a pay-to-play operation, if you get what I mean.

The broader problem with slippery slope arguments is that defining precise limits on things is essentially what governments do. The Medicare schedule, for instance, precisely delineates what the Government will pay for, and what it will not.

Sometimes these lines can move over time — but again, that is what government is supposed to do. Australian governments once prevented Aboriginal people from marrying non-Aboriginal people. Now, they don't, because we know better. Ending dowries, changing ages of consent, no-fault divorce — all evolutions in marriage.

Nobody thinks you can marry a road, and I know this because I've been trying to make an honest span of Brisbane's Go-Between Bridge for years. Besides, Sydney Harbour Bridge fans know that the Bradfield Highway already is very much hitched to the Cahill Expressway.

In recent days, Cory Bernardi has made his own version of this argument via a "pink rainbow Trojan horse", which looks so much like a My Little Pony that he may well accidentally convince impressionable young girls that marriage equality involves rainbows, sparkles and magic friendship. Which, to be fair, it does.

2. Kevin Andrews' cycling buddies

Our politicians love arguing via analogies, which is where you try to make a point about something controversial by pointing out something uncontroversial. This rhetorical device is known as the straw man.

Former prime minster Tony Abbott and backbencher Kevin Andrews sit together in Parliament in March. ( ABC News: Matt Roberts )

In the early days of this debate, Coalition backbencher Kevin Andrews made an analogy between same-sex couples and his cycling buddies.

"I have an affectionate relationship with my cycling mates, we go cycling on the weekend," he said, invoking an image of middle-aged men in cycling garb that many of us are still frantically trying to purge from their retinas. "But that's not marriage."

Well, no, unless the Pollie Pedal regularly transitions into a Polyamory Pedal — but Andrews' point seems a better justification for a ban on Lycra than a ban on gay marriage.

Not all "friendly" relationships should be recognised via marriage — well, yes.

As Wizard of Oz fans know, straw men generally display more logical acumen than this.

Perhaps the most generous thing that can be said here is that in such a heated debate, it's lovely to have at least one thing on which we can all agree.

Which is not to say that if the law changes, two male cycling mates shouldn't be able to get hitched if they so desire. And if they do, Kevin Andrews would no doubt recommend that they have some marriage counselling beforehand.

3. Political correctness gone mad!

Tony Abbott, who has a particular genius for opposing things, claims that people should oppose same-sex marriage if they don't like political correctness — which is of course, well beyond the bounds of the very limited question being asked by the ABS.

Sorry, this video has expired Tony Abbott welcomes postal vote on same-sex marriage

"I say to you, if you don't like same-sex marriage, vote no," he said, which is indisputably sensible advice, as that's the question on the table.

But then he went on. "If you're worried about religious freedom, and freedom of speech, vote no. If you don't like political correctness, vote no — because voting no will help to stop political correctness in its tracks."

This feels a bit like tone policing, fittingly for a Tony who used to live in a police college. Tone policing is a kind of "genetic fallacy", where you look at where an argument came from instead of what it says.

Here, Abbott is discrediting an argument by focussing on the way people express it — so instead of judging marriage equality on its merits, you reject it because it's just another instance of how namby-pamby lefties are always whining on about some vegan intersex poetry, or some other equally crude stereotype.

You reduce an argument to just more "blah blah blah" from the usual suspects.

But even though many of those on the left can admittedly be incredibly annoying, it doesn't mean they're wrong.

Similarly, Tony Abbott isn't necessarily wrong on occasions when he's sober just because he sometimes enjoys the company of Kevin Andrews and Peter Costello more than most people would imagine possible.

4. Won't someone think of the children?

This is a favourite of Lyle Shelton from the Australian Christian Lobby, and is what's known in formal logic as an appeal to tradition — the view that because something has long been the case, it must therefore remain so.

An appeal to tradition: Australian Christian Lobby managing director Lyle Shelton. ( AAP: Mick Tsikas )

But even though some of Australia's social mores are derived from Christian societies in Europe, our Parliament is constitutionally barred from imposing one religion on all of us, and the current debate is about secular marriage of the sort already performed by celebrants for those seeking to avoid the involvement of the church.

Of course, the Anglican Church itself was created so Henry VIII could get divorced — and let's not forget that Jesus was raised by a man who was not his biological father, which might suggest the virtue of sympathy for blended families.

The idea that kids need the active involvement of a father and a mother to be "normal" is not borne out by data, or in the many same-sex and single-parent families we already have, but it remains powerful after centuries of being the social norm.

Of course, this has very little to do with the question at hand.

Lyle Shelton is making a case for non-straight couples to be prevented from having children.

But they already can, and nobody appears to contemplate preventing them, so the proponents of this argument instead uses their concern to justify his opposition to same-sex marriage.

The survey question does have one clear connection to children, as answering yes would allow the many same-sex couples who currently co-parent to get married and some conservatives — such as David Cameron — who believe marriage is a precious source of familial stability support same-sex marriage on that basis.

5. What if it teaches people it's okay to be gay?

"Kids in Year 7 were asked to role-play being a same-sex relationship", warned one of the women in the Coalition for Marriage's first ad. I remember studying Macbeth in school and being asked to role-play both the Scottish king and his wife, and somehow that hasn't turned me into a mass-murderer. I also acted out Who's Afraid of Virginia Woolf? in a high school English class, and so far my marriage has yet to descend to anything like those depths, fortunately.

Sorry, this video has expired The first ad ahead of the same-sex marriage survey

Many of these arguments display a discomfort for gay and lesbian people in general. While of course people are entitled to their private views, acting on that discomfort contravenes antidiscrimination laws, and tends to make people social pariahs — sorry, young lawyers.

I wish kids in my high school had been asked to role-play gay relationships in Year 7. "Gay" was used constantly as a slur in the playground. Some of my classmates have now come out, and I just hate to think how difficult we must've made things for them.

As opposed to the other arguments listed above, there is no rhetorical sleight of hand going on here. The two options are a society where many people are told that their sexuality is wrong and suffer as a result, or a society where consenting adults are allowed to love other adults as they please.

We've already resolved the legality question of homosexual sexual relationships. Nobody is seriously proposing recriminalising that, thank goodness.

But some of the arguments proposed by the No case betray discomfort with those relationships in general.

And while "you can say no" to marriage equality, as the Coalition for Marriage reminds us, we can't legally say no to homosexuality, not any more.

So it's now a question of whether we take the next step beyond legalisation, and treat gay and lesbian relationships as truly equal.

Dom Knight is a writer, broadcaster, and co-founder of The Chaser.