SARAH Silverman. Sarah who? Don't use that name around here - don't you know she's been cancelled.

A quick precis: "cancel culture" is nothing new, it's been around since about 2013 or so. If you are an actor, a politician, anyone in the public eye, and you stray from modern proscribed cultural mores then you are cancelled.

That is, ignored on social media, boycotted, shunned.

The Scottish comedian Limmy uses the phrase to great effect on Twitter as a lampoon of the genre, sending up the lack of nuance in cutting someone off for not toeing the accepted line. Any minor infraction is met with a tweet: "Such and such is cancelled."

It is, though, not always a lampoon. In February this year the actor Liam Neeson was cancelled for the extraordinary interview in which he admitted decades-old thoughts about seeking revenge on a black man - any black man - after his friend was raped.

The premiere of his latest movie was cancelled, the filmmaker Spike Lee said he would no longer work with him and he was derided almost unilaterally. Very few stepped forward in Mr Neeson's defence and they suffered, then, similar derision.

Ms Silverman has sparked the latest cancel culture headlines by revealing, while a guest on The Bill Simmons Podcast, that she was recently fired the night before beginning filming for a movie after producers became aware of a photograph of her in blackface.

The picture was taken from a sketch in her comedy series The Sarah Silverman Programme in 2007 and has haunted her ever since. In interviews she is routinely asked about it, her contrition ebbing and returning.

She has said it was her most "regrettable joke", this in 2015, but added the caveat that the picture was being taken out of context. “Now it’s forever [on Twitter] and it looks … it’s totally racist out of context and I regret that.”

In 2018 the comedian said, in fact, she doesn't stand by the blackface sketch at all, roundly condemning herself with: “I’m horrified by it, and I can’t erase it. I can only be changed by it and move on.”

Just a year later and she has returned to sounding that little less contrite.

"I didn’t fight it," she said of her sacking. "They hired someone else who is wonderful but who has never stuck their neck out. It was so disheartening.

"It just made me real, real sad, because I really kind of devoted my life to making it right."

Stuck their neck out? What an unfortunate turn of phrase to describe acting in a way that is, unequivocally, racist. Comedy exists to cause offence; comedy can be gross, appalling, seething, grim. Racist? No.

Blackface is not sticking your neck out, it's making a mistake, it's causing gratuitous, unintelligent, unintelligible offence.

But let's say Ms Silverman is sorry, and not just because she was caught. She raises an interesting point: when and how does forgiveness come, if sinners can be forgiven at all?

Society is constantly shuffling and reshuffling the cards of acceptability and respectability. It is not always easy to keep up - not with changing standards and not with the accompanying language.

You know, as a member of the centre left, that your long held beliefs will one day come into question. Perhaps the boundaries of your feminism will be tested. Perhaps your tolerance or sympathy for those who tediously expand the quota of banned words and phrases dwindles.

You may coast along with a clear conscience and the moral certainty of your progressive attitudes until you find yourself gradually slipping into the centre space of a Venn diagram, overlapping you with "evil conservatives".

I'm an upper aged Millennial yet already constantly feel morally judged by those, say, 10 years younger and feel my patience wearing. It's downhill from here.

Some societal boundaries we should know as certain, one such being that racism is abhorrent. You would hope, 12 years later, that a comedian would not consider blackface an amusing addition to their repertoire.

Let's say Ms Silverman is truly appalled at her behaviour. She knows it is wrong. She would never do such again. She stops adding caveats to her apologies.

It is, of course, a huge ask for her black audience to forgive her. It must feel even more a let down that someone who purports to be an ally would do such a thing. It must be galling for a person's racism to be then held up as a learning opportunity and a jumping off point for public conversation.

Or a person's misogyny or homophobia or ableism or any number of other issues. But expressing horror at past faults is conciliatory.

These conversations do help to move us forward as a society. That's not to suggest we might be thankful for celebrity misogyny as a learning opportunity.

But if we are to constantly evolve what is acceptable and what is verboten then we have to talk about it. We have to be able to explain why a view is wrong as we condemn it and then forgive.

After all, with righteousness based on such shifting sands, the next error might be yours.