As the law and order select committee members sat around gob-smacked at the very thought of legalising incest, the professor who suggested the law change was equally perturbed at their reaction.

The MPs said and did "nothing", asking no intelligent questions, philosophical historian Professor Peter Munz told the Herald.

At 83, Professor Munz, retired professor emeritus of history at Victoria University, still speaks with a German accent despite having lived in New Zealand since his Jewish family escaped World War II and came here more than 60 years ago.

He says the MPs ought to have at least tried to understand the theoretical argument in his submission on legalising incest between consenting adults when he fronted up this week to the law and order select committee on the Crimes Amendment Bill.

The submission, he says, arose out of a book he has been researching for years on the evolution of cultures.

His submission explains: "The prohibition of incest is completely universal in early Palaeolithic societies and has lingered on ever since. But in modern civil societies it is an outmoded prohibition."

He believes that in Palaeolithic tribes, women were not available for "consumption" at home.

They had to be kept and treasured as capital to be invested in fomenting alliances with so-called foreigners - and incest amounted to the wasteful consumption of such capital at home. Thus, it had to be prohibited.

Professor Munz sees no problem with incest these days if adults consent.

But the argument, presented to the select committee this week, got nowhere with the MPs.

"I was amazed with the reaction of the select committee ... I don't expect them to agree with me but I did expect them to ask intelligent questions."

Members were so bewildered they failed to even stare at him with their mouths open: "Total lack of comprehension, and then they simply said no."

When it is put to him that surely most people find the whole idea icky, Professor Munz says there is nothing urgent about a law change because incest hardly ever occurs anyway.

He stresses that he is talking only about consenting adults. "I'm not talking about fathers abusing children and so on."

As a rule, brothers are not attracted to their sisters or vice versa. They are too familiar and are not objects of sexual attraction, "and this is why this whole question of whether incest should be legal or not legal is really a theoretical one".

The topic, like legalising homosexuality and same-sex marriages, is highly emotional and people do not really reason it out.

Professor Munz bursts out laughing when asked what he thinks of being viewed as a nutty professor.

"It's hardly a nutty subject. I mean, there's a huge literature and anthropology and history about it and psychology, so to call me nutty just shows how ignorant people are."

The BBC has interviewed him and an American network rang yesterday. He is gratified that both were seriously interested in his historical arguments.

Colleagues the Herald spoke to also confirmed there was nothing nutty about Professor Munz.

He has written scores of books and was a lifelong friend of philosopher Karl Popper and is held in extremely high regard.

The late Dr Michael King, once a student of his, dedicated his last book, A Penguin History of New Zealand, to him.

Professor Munz confesses he is not afraid of controversy and is a prolific letter-to-the-editor writer, saying his letters are mainly attacking Israel, which he calls one of the great blemishes of modern civilisation.

"I mean, I'm Jewish myself and I find it absolutely devastating how other Jews can do things like steal other people's lands and then kill them."