Why are we not worried by an unmarried mother leading the country? Once we would have been.

Once in the 1970s, I was approached by a producer about whether I had a proposition which could be debated on television. The idea was to use a court format with a jury of twelve to decide. I suggested a number of possibilities; they picked the notion that marriage should be between two people and that the state should not be involved (except that it might have a voluntary register).

My interest reflected two issues. One was tax and social security policy where the significance of legal status was receding and yet was increasingly complicated. The other was that I was – and still am, as we shall see – uneasy about the state having too much involvement in our private lives. I was not against marriage. The issue was whether it should be a relationship between two consenting adults or whether the state should be involved imposing its rules and regulations.

We filmed the event, the producer was satisfied with the debate, but astonished that all twelve of the jury rejected the proposition. So we did it again with another jury who unanimously agreed with the first. (One juror, with a considered and devout demeanour, said that he thought his marriage was between him and his wife and his church and the state was not really involved. Even so, he voted with the others.)

That was it was like in the 1970s. Today the prime minister is, as they say, ‘unwed’, living with a partner and even with a baby. (I wont go into 1970's concerns about unmarried mothers, but every unmarried mother was visited by a social worker shortly after the birth.) They are not alone in such a partnership arrangement. Hardly anyone seems worried. Indeed the relationship and birth will be celebrated all over the front covers of the Women’s Weekly and The Listener – just as Harry and Meghan’s formal wedding was celebrated a few weeks earlier. We have come a long, but confused, way.

Even in the 1970s there were couples said to be ‘living in sin’, a phrase I rarely hear today. I do not know of any detailed documentation of the evolution. Among the important events was the Property (Relationships) Act, which covers all of couples who are married, in a civil union or in a de facto relationship, when the relationship has ended by separation or death.

The law sets out what happens if the relationship is based on an informal and incomplete contract (or understanding), as it commonly is. There seems to be a proper role for the state to set rules for the unwinding of such partnerships – it also does for business relationships – rather than leaving the exercise to a tortuous and expensive proceeding through the courts (although because of personal circumstances the breakup can still be very complicated). Note that the provisions in the act can be overruled by a private contract.

Another development has been enabling a same-sex couple to formalise their partnership in a marriage or civil union. A practical reason was that in certain emergencies – say involving a comatose person – it would tell the authorities who was in charge, although that can also be done via an enduring power of attorney. My impression is that my gay friends who took the state options wanted to be seen as conventional, and the convention was marriage. (There was also the opportunity to formalise the relationship in front of their friends – I have been to some good gay weddings – and, for some, the sacramental dimension is important.) The jury would have gone ballistic if that proposition had been put up in the 1970s.

The point is that if we have state intervention in private relationships it should not be discriminatory; it was not so long ago that some jurisdictions prohibited marriage (or even sex) between individuals of different races.

So while there may have been outriders advocating a new way, organic evolution worked better. However it required sensitive state support. (Is Edmund Burke nodding?)

Sometimes the state needs to be more involved. In my view children have full human rights although they require a guardian to ensure they are met. Normally they are the parents of the children who do not ‘own’ or have other rights them. The guardians have only responsibilities; if they fail in exercising them the state becomes more involved. The overriding principle should be the best interests of the child. At least that is my view even if it is not current situation.

These examples illustrate an issue which has been at the centre of my thinking over the decades. Where should the state be involved, where should the state butt out? In economics, as this column regularly returns to, the issue, which while far from straightforward, has a formal analytic framework. In private lives there is not even that.

This is not to advocate a Royal Commission pondering on where the line should be drawn for such civil matters. The failed TV program taught me is that is not how it happens. The 24 jurors were not voting for state marriage, but for a kind of marriage about which they understood involved the state. As their children and grandchildren solved the issues in ways novel to them, they adapted, but not overnight. (No doubt some have not and will not to their dying day. Sad.)

Yet the outriders have a critical role in the evolution. If organic evolution often needs some state support, we need to be thinking about how to adapt the institutions of the state at an appropriate rate. Some of the outriders – not all of them – are pointing to where we might be going. We need to listen to them. Even so, today I would usually be with the 24 jurors, although I would like to think that some of them went home pondering where we might go and what we should do about it. Any way, we are getting them.