Last year, former Howard-Government Minister Amanda Vanstone appeared on a popular television panel show. The issue of same-sex marriage came up, and in strident Vanstone style she declared her support. Asked why, Vanstone said: “Well we say that marriage is a union of a man and a woman, to the exclusion of all others, for life. Two of those are already gone, so why are we so upset about the third?”

Unfortunately, generations of broken marriages mean that society no longer sees its importance.  Yet if we recognise the importance of marriage, we will want to strengthen the institution.

This is why these arguments are raised and why they continue to be a problem.

Here is a rough and ready crash course on why they’re wrong:

1. Shouldn’t the church and state be separate?

This argument is about the government’s approval of a Christian definition of marriage. Proponents claim that this amounts to the government’s involvement in a Christian institution, violating the separation of church and state.

This argument might be valid if the government had a religious motivation for being in the marriage business. But it does not. Rather, the government is in the marriage business because it is interested in children.

Good governments are firstly concerned about a sustainable, functional and healthy society. The best way to ensure this is through the good formation of children. Children are formed best in a stable family, with their biological mother and father.

This is why children have the right to the stability and diversity of their biological mother and father, wherever possible.

The government is in the marriage business because it is interested in children, not religion.

2. Why are we even bothering when marriage is already so broken?

This is Amanda Vanstone’s argument. If marriage is no longer “for life” or “to the exclusion of all others” then what difference would same-sex marriage make?

But you see, good marriages are good for society.  They’re good for kids and they build strong families and strong communities.   The family unit is society’s best social welfare safety net.  Family is the building block on which economy, society, civility and children are built. Marriage really matters.

Preserving marriage is not just about stopping same-sex marriage; it is also about building and securing the future for our society of this important building block.

Preserving marriage is about securing a better future for society.

3. Doesn’t saying ‘no’ to same-sex marriage entrench inequality?

This argument claims that a same-sex attracted person must not be denied the right to marry someone of the same-sex. Such a denial, the argument goes, is discrimination and is morally wrong.

However this assumes that not everybody currently has an equal right to marry. But they do. Every person has the right to enter a marital union. The reality is that not everybody wants to enter a union of this kind.

To buy this argument requires us to redefine “marriage”, not with a fixed definition, but according to a person’s romantic interests.

So what about the “right” of someone with romantic interests that amounts to a homosexual threesome? A bisexual quartet? A polygamous relationship? Plenty such people exist and do want to marry. If it is a human right to claim “marriage” for one’s romantic interest, then there is no good reason to deny them. The principle quickly becomes nonsensical.

Thankfully, the government is not in the marriage business because it's interested in your love life.

The federal Marriage Act applies to everybody the same way.  It does not discriminate.

4. But won’t redefining marriage make our society more free?

This argument says that people ought to be able to do whatever they want. Governments should get out of private lives. Government should get out of marriage.

But marriage is a vital institution by which the libertarian ideal of small government can be realised. As a simple, civil institution, it solves most welfare and social security problems. It also nurtures stable children and thus the kinds of people who prosper without government help.

Libertarians don’t often measure their policies by looking at the consequences, but in this case they should.

Marriage makes good libertarians through minimum government involvement.

5. What about interracial marriage?

This argument says that denying homosexual marriage is no different from denying interracial marriage. Homosexuals are victims of the same injustice.

Marriage is about children and therefore about biological parents (or replicating, as near as possible, the biological parent environment for orphaned, deserted or abused children). Race has nothing to do with marriage. This is precisely why the ban on interracial marriage was unjust.

As an aside, note also that sexuality is an entirely different category of thing compared with skin colour. The latter is fixed and immovable; the former is changeable and fluid. The latter is physical; the former is behavioural. The latter cannot be subject to ethical judgement, but behaviour can.

Gender matters for marriage. Race does not.