Screaming “I'm right and you're wrong” until your opponent sees the error of his ways works well on my husband, but I doubt Julie Anne Genter would change her mind if new evidence emerged that the costs of cycle ways in central Wellington outweigh the benefits.

Knowledge is evidence based, but it doesn’t work by insisting on the correctness of your facts. Like science, it works by posing a hypothesis and having others set out to prove it wrong.
It advances only when others try to knock your idea down. If it survives the assault, then chances are it’s a good idea.

I asked Jonathan Rauch how the progressive left, once the champions of free speech, have become the “Gluten Free for Palestine” protesters intimidating and barring Jewish students from entering New York’s Columbia university.

Rauch (who is being hosted here by the Free Speech Union) says some who see themselves as progressive see “hate speech” as a form of violence used in the past to threaten minorities and soak societies with racism, homophobia and misogyny. The past was certainly soaked in bigotry. But that was not the fault of liberalism. It was a failure to embrace it.

Enlightenment liberalism existed in many cultures, including among those Muslim thinkers who rescued Greek libraries and texts. There is nothing colonial about the pursuit of knowledge through free speech.

The university’s “kindly inquisitors” (another Rauch book), who seek to protect people from offence with censorship, have good intentions, but “inevitably in all places and times, with only rare exceptions, the advocates of freedom of speech are the people who fear the most from censorship. And the people who have the power to censor are the least amenable to freedom of speech.”

“In the modern context of cultural and idea-making institutions of journalism and academia, for example, the power to censor is now effectively in the hands of the left.” It is human not to want to give up that power.

Read Josie's column on the left and free speech.