It was just a matter of time before the contemporary left started turning on itself. After all, this had been the practice of communist and other radical left-wing movements in the 20th century. Splitting is what ideologues do to proclaim the truth of their particular ideologies.

On any analysis, The New York Times is a liberal newspaper, in the North American sense of the term. In other words, it’s on the left. Not the extreme left but the left nevertheless. Look at it this way; Donald Trump cannot abide the NYT. For its part, the paper is a leading critic of the President and his administration.

The error of The New York Times was to publish an opinion piece by Republican senator Tom Cotton that supported the tough-minded policies of the Trump administration to deal with the looting and burning that followed the tragic killing of black American George Floyd by a white policeman in Democrat-run Minnesota.

The left had forced out of a job another member of the left for allowing a conservative a say.

A less significant version of this attitude has occurred in Australia. Tasmanian Labor senator Helen Polley recently posted this message on Facebook: “Instead of black lives matter, how about every life matters, no matter what the colour of your skin is.”

This meme was condemned as racist. Polley removed the post and apologised. As a parliamentarian, she cannot lose her job because of public pressure.

Polley is a mainstream social democrat whose family has long-time connections with the Labor Party in Tasmania. She’s a conservative on social matters but is in no sense racist. Once again, as with Bennet, it was the left who condemned one of its own.

David Bartlett, a former Labor premier of Tasmania, tweeted: “It’s Hanson lite. It is tin-eared and a classic dog whistle. Remove it.” He also called on Polley to “educate yourself” — a term not distant from the “re-education” beloved of various communist regimes. And that’s the problem with the contemporary intolerant left. It’s not sufficient for the likes of Bennet to apologise.

No, they must be driven from their employment and/or volunteer for re-education. They are in error — and error has no rights.

There is nothing new about ideology-driven intolerance. It’s just that this is becoming increasingly widespread on the left.

At Australian universities in the late 1960s and into the 70s, the extreme left was into shutting down debate and driving speakers it regarded as conservatives off the campus.

A half-century ago, German-born American Marxist philosopher Herbert Marcuse was a hero of left-wing activists — although it was not clear if any had read his rather turgid prose. In his 1965 essay titled Repressive Tolerance, Marcuse advocated “intolerance against movements from the right and toleration of movements from the left”.

Marcuse’s essay was a long-winded effort aimed at intellectually rationalising the silencing of his political opponents — he called it “liberating tolerance”. It was a matter of out with debate and in with “truth” as determined by Marcuse and his like-minded comrades. What Marcuse did was to give an intellectual cover for old-fashioned political censorship. The rationalisation that conflicting views should not be heard because they are not deserving of a hearing. This concept pertains to the current debate.

The killing of Floyd has, or should have, opened up a genuine debate about race relations in Western societies and what makes for appropriate forms of protest.

Here a couple of case studies demonstrate the intolerance of the contemporary left.

On June 5, Fox News presenter Shannon Bream interviewed two commentators on the protests/riots in Washington on her Night Courtprogram, namely civil rights black attorney Robert Patillo and white lawyer and journalist Alex Swoyer.

Patillo was broadly critical of how the Trump administration had responded to the unrest in the capital while Swoyer was broadly supportive. It was a vigorous but respectful debate. Some viewers would have backed Patillo and others Swoyer, while others still might have changed their minds after hearing the intelligent but forceful discussion.

On June 9, ABC Radio National Breakfast presenter Fran Kelly did a long interview with two commentators on the unrest in US cities. They were Imani Perry, professor of African-American studies at Princeton University, and The Guardian columnist Richard Wolffe.

Fox News is owned by Rupert Murdoch and is subscription television. The ABC, on the other hand, is paid for by the Australian taxpayers and consequently has an obligation to be fair and balanced. But those listening to the Perry-Wolffe discussion would have heard only criticism of Trump and his administration to a greater or lesser extent.

Kelly quoted from various one-time Republicans who always were or have become “Never Trumpers” — the likes of Mitt Romney, Colin Powell, Jim Mattis, George W. Bush and so on.

Perry accused Trump of rejecting the stated core values of the US nation, putting out quite violent messages directed towards black Americans and engaging in the advocacy of Nazis.

For his part, Wolffe accused Trump of playing on racial prejudice, inciting violence at rallies and so on. No other view was heard.

A similar debate, for want of a better word, took place on RN Breakfast on June 3. Kelly interviewed Catholic priest Edward Beck followed by one-time Barack Obama counsel Jeffrey Bleich. Both bagged Trump. Once again, no other view was heard.

There is no conscious conspiracy here. It’s just that the ABC is a conservative-free zone in which many presenters and producers do not consider views contrary to their own to be worthy of a hearing. In this sense the impact of Marcuse’s thought extends beyond the grave.