AFTER accepting a peerage, Dafydd Wigley's next-worst mistake was to attempt an ancient style of philosophical argument.

The modern world accepts most things, but not subtlety. When words have been rendered sacred, subtlety is - for ironies still endure - taboo.

The Lord Wigley was trying reductio ad absurdam in arguments over the future of the Trident boats if Scotland's government insists on getting shot of the things. The peer said: "Look, this week we have been remembering what happened in Germany before the war. No doubt there were many jobs provided in Auschwitz and places like that, but that didn't justify their existence, and neither does nuclear weapons justify having them in Pembrokeshire."

Granted: a bit crass. Granted: deploying an historic abomination in the context of a merely-theoretical defence policy dispute was probably a step too far. But Wigley's real offence - for which he was forced to apologise - was even to mention Shoah in the context of nuclear weapons and modern politics. For contemporary purposes, the Holocaust has been put beyond use.

Perhaps that's as it should be. Perhaps even those who inveigh against political correctness have got the point. Words are anchored in reality and reality is touched by the words we use. But consider what Wigley actually said, and what he didn't say.

He said, explicitly, that the vast industry created around Nazi extermination camps "didn't justify their existence". He didn't say, though he might have, that if even a couple of the UK's missiles go astray six million dead will be the least of our guilt. Yet in the week in which David Cameron and his peers made remembrance for what a species allowed to be done to Jews, language was policed.

We have new versions of sacred and profane. Most of us have a rough idea of how it works. Our "sensitivity" to nouns, adjectives, verbs and history have allowed actual monsters to shut down argument. You cannot - trust me - criticise the State of Israel unless you wish to be known as an anti-Semite. You can't say a word against demented jihadi thugs without being numbered an Islamophobe. In a trivial way, you can't use historical facts when writing of dear old Sir Winston.

It doesn't help. People like plain speech. They depend, ultimately, on those bits of speech that can be justified by facts. They grow weary of incessant lying and of those who exploit respect to alter the terms under which speech is - but who decided? - allowed. Lord Wigley was put through the mill for making an unexceptional point that asked people to think. Then he "exploited" Auschwitz?

He didn't. Wigley's offence had nothing to do with facts and everything to do with language. After Charlie Hebdo, we are all - or so I hear - fans of free speech. We are less enthusiastic about what that freedom, where it exists, might actually mean. He said what? He used which word? Is there now an official social media storm descending on his head? If not, why not? Bring pitchforks, torches, and your God-given decency.

It winds up, as most of these things must, with our American friends. When the first amendment to your constitution is a form of speech guaranteeing free speech - and none of that European "abridging" - you have created a couple of interesting problems. The citizen can say what the hell he or she likes. This is an excellent notion. But the citizen, it turns out, is less keen on her fellow citizens taking refuge in common liberties. What follows?

A racist society that can manage the spectacle of young black men shot dead in the process of surrendering is agitated, it seems, when posh Brit actors get their euphemisms wrong. I don't sympathise with Benedict Cumberbatch, exactly. If you've been raised in Britain, far less America, "coloured", in any context, reeks of assumptions and ignorance. But the fuss over a word is as revealing as the word.

I grew up in a world in which blacks, homeless dogs and Irish couldn't get a room for the night, in which "coloured" was BBC code for the next horrifying alien. Not so very long ago, in these parts, terrible epithets were common speech and skin colour was the usual place for bigots to start. Now I'm only amazed that an expensively-educated English actor failed to hear the words in his head.

But I know, more or less, how America works. A profoundly racist society makes an enormous deal out of nickel-and-dime speech acts while ignoring its daily realities. You can put a dozen rounds into the black kid as long as you don't use "the N-word" on prime-time. You can report the official sanitised version of relentless racism as long as the guest-Brit remembers to say "African-American" instead of some outmoded codeword. Just be careful, very careful, not to cause offence.

Something odd is going on. For the sake of decency, and because those with power believe that suppression works, free speech is everyone's official belief and no-one's habit. We exist, contentedly, in a censorious culture that doesn't think twice about "reporting" a neighbour to self-selected internet providers and nothing of the right to say "Auschwitz" for argument's sake.

It's not about the Holocaust. It's about the human habit of refusing free thought - speech, if you're very lucky - when the issues before us are hatred, common abuse, and wholesale daily genocide. I'll consider the world as improving, and off the danger list, when the vast lists of words for "not-us" have become bits of disgusting history. But I'm not confident.

For now, shutting down speech has become a kind of collective excuse, as though to say that if we don't hear it, it can't be happening. We police our language better than we police the streets where our poorest children live. We watch over our adjectives better than we watch over our lost souls. We calibrate our offences with more attention than we attend - just a stray stat - to the fact that 13 children died at home in the US because of guns for every American hero dead in Afghanistan.

Free speech is supposed to be its own remedy. Had I been sitting with Cumberbatch before his fateful remarks, I might have observed that he is "coloured" too. Bit pasty, a little blotchy, not genetically attractive: white. People who called themselves black made jokes about that for my benefit a long time ago. And in those days they used that "N-word" with abandon.

The list of words a decent person should avoid seems to lengthen by the day. It's an imperfect answer to bigotry. It doesn't assist art and seems, in any case, only to aid the censorious, the puppets of every age. This newspaper, like every family newspaper, has a list of words forbidden to advocates of free speech who might want to use a word or two. Which fact is, of course, funny.

The enemy currently, as Daffyd Wigley has discovered, is a weird notion called "respect". When grief is profound, all must - add an asterisk - shut up. But it won't do and we won't.