One of the world's leading experts on intelligence says no one should listen to anything Stefan Molyneux has to say on the topic.

But not necessarily because he's wrong.

Emeritus Professor James Flynn of the University of Otago has published a number of books and papers on intelligence, what it is, and what's behind it. He's best-known internationally for the 'Flynn effect' - the gradual improvement in intelligence - as measured in IQ tests - that occurred throughout the 20th century.

If you've been following the news over the past few weeks, Mr Molyneux probably needs no introduction. For the rest of you, he's a Canadian podcaster and YouTube personality who was going to speak in Auckland last Friday with alt-right provocateur Lauren Southern, before a backlash convinced the venue's operators to cancel the show at the last minute.

He argues there is a racial link to intelligence, with a hierarchy that puts Ashkenazi Jews at the top, African-Americans, sub-Saharan Africans, pygmys and indigenous Australians at the bottom, and the rest of us somewhere in between.

Mr Molyneux says while he doesn't like that different races have different levels of intelligence, it's what the research says, citing work by the likes of Prof Flynn and Charles Murray. The latter published a book in 1994 called The Bell Curve, which presented evidence of IQ differences between the different races. While it didn't flat-out say the differences were the result of genetics, in promotion for the book Dr Murray said it was likely.

Prof Flynn was interviewed by Mr Molyneux in 2015 - the hour-long chat is on YouTube - but said if the Canadian called now, he wouldn't answer.

"I wouldn't think of going within a mile of him if he talked," Prof Flynn told Newshub, saying while he enjoyed debating the subject of race and IQ with academics he disagreed with, such as Dr Murray and the late Arthur Jensen, there was no point in listening to what Mr Molyneux has to say.

"These people are just coattail-hangers. They don't have anything new to contribute to the debate - they just try and make the debate spectacular. I've invested a huge amount of time on this issue, read all the best thinkers, and wouldn't think it would be worth my time."