THE Convention on the Constitution gets around to its most controversial topic this weekend, namely same-sex marriage.
Opinion polls show majority support for it, ranging from 74pc in one poll frequently cited by proponents of same-sex marriage, down to 53pc in an 'Irish Times' poll a few months ago. That one is less frequently cited.
Whichever one is closer to the reality, however, it's beyond doubt that there is widespread support in Ireland for same-sex marriage.
But how deep is this support? In the Meath-East by-election, Labour candidate Eoin Holmes placed huge emphasis on Labour support for gay marriage and abortion legislation but no one was interested. He won 4.6pc of the vote.
At the outset of last year's Children's Referendum, one poll showed 74pc of people would vote in favour of it and only 4pc against.
On the day itself, 42pc voted against it. Therefore opposition grew more than tenfold in only a month. This was despite the fact that the No campaign had no money and few spokespeople.
The fact is that when a referendum begins, all bets are off.
This is why in 32 cases out of 34 in the US, states have passed referendums defining marriage as being between a man and a woman, even though polls frequently showed the contrary position leading at the start of a given campaign.
In the only vote held to date on the matter in Europe – in Slovenia – gay marriage supporters were 20 points ahead with days to go but lost by 10 points on the day itself.
Why does this turnaround happen again and again? The reason is that the debate about gay marriage at its heart is a debate about how highly we value motherhood and fatherhood and whether we think the complementarity of men and women, especially as mothers and fathers, should be embodied in a special and distinct social institution.
People often ask, "what harm would it do if we allow two men or two women to marry one another?" But the harm is in the outright denial by proponents of gay marriage that there is any added value in children having a loving mother and father.
In the name of 'tolerance' and 'equality' Irish people are being asked to abandon the notion that motherhood and fatherhood are complementary roles of special value to children and society.
Gay marriage supporters don't only want to make marriage gender neutral. They want to make parenthood gender neutral.
They want us to agree that marriage should be for any two people who love each other, regardless of sex, and that having two loving parents is just the same as having a loving mother and father.
These two demands are inseparable. You can't have one without the other and they amount to an outright denial of sexual complementarity.
While gay marriage proponents can hardly deny that there are two sexes, they emphatically deny that they are complementary in any significant way, least of all from the point of view of children.
They insist that the 'blend' of mother and father adds nothing to the rearing of children. And yet in politics and business we're told it's essential to have a blend of men and women, hence the demand for gender quotas.
Furthermore, gay marriage proponents insist that the natural ties are of no importance. Obviously when a same-sex couple has a child, the child can be biologically related to one of them only, that is, a natural tie can exist to only one of the parent figures.
The other biological parent, without whom the child cannot exist, is out there somewhere and the child may never know who that person is or ever have any contact with that person.
But we know that adopted children frequently go looking for their natural parents.
So the natural ties do matter, regardless of what supporters of same-sex marriage say.
The huge irony in all this is, of course, that gay marriage supporters tell us to "celebrate difference" but then pretend the differences between men and women and mothers and fathers aren't important.
Gay marriage proponents insist that they are discriminated against because they can't marry. But is it really discrimination to create a social institution which recognises that the two sexes are distinct and different and complementary, and then another legal structure for other kinds of relationships?
It is often countered, of course, that infertile men and women are allowed to marry. But their marriages in no way contradict the fact that the two sexes are distinct and different and complementary in ways that matter to children and society.
So the question before the convention delegates this weekend is a relatively simple one; do they believe that there are real and complementary differences between men and women and mothers and fathers, and if so, do they really believe it is unjust discrimination to have a special social institution which embodies these differences?