I have a rule that I try to stick to, but which I break occasionally. That rule is “never say anything remotely contentious on Twitter”. No good ever comes of it. Arguments that need plenty of space and thought get compressed into 280 characters and defended in front of a baying audience; it is the worst possible medium for serious conversations.

Richard Dawkins does not have the same rule, I think it’s fair to say. “It’s one thing to deplore eugenics on ideological, political, moral grounds,” he tweeted recently. “It’s quite another to conclude that it wouldn’t work in practice.”

Lots of people got very cross about that, and I was naively surprised; surprised enough to break my own rule. I thought he was saying something fairly obvious, which is that if you bred humans for some trait then it would probably make that trait more common, and that he was explicit in saying he wasn’t talking about whether it was morally acceptable. But other people thought — they told me so — that he was literally in favour of eugenics. (Dawkins later clarified that no, he was not: “I deplore the idea of a eugenic policy [but just] as we breed cows to yield more milk, we could breed humans to run faster or jump higher. Heaven forbid that we do it.”)

The analyst John Nerst, who writes a fascinating blog called “Everything Studies”, is very interested in how and why we disagree. And one thing he says is that for a certain kind of nerdy, “rational” thinker, there is a magic ritual you can perform. You say “By X, I don’t mean Y.”

Having performed that ritual, you ward off the evil spirits. You isolate the thing you’re talking about from all the concepts attached to it. So you can say things like “if we accept that IQ is heritable, then”, and so on, following the implications of the hypothetical without endorsing them. Nerst uses the term “decoupling”, and says that some people are “high-decouplers”, who are comfortable separating and isolating ideas like that.

'Eugenics is possible' is not the same as 'eugenics is good' By Tom Chivers

Other people are low-decouplers, who see ideas as inextricable from their contexts. For them, the ritual lacks magic power. You say “By X, I don’t mean Y,” but when you say X, they will still hear Y. The context in which Nerst was discussing it was a big row that broke out a year or two ago between Ezra Klein and Sam Harris after Harris interviewed Charles Murray about race and IQ.

As a high-decoupler, Harris thought that it was OK to talk about what-ifs; if there are genetic components to racial differences, then we still need to treat everyone with equal dignity, etc: “I’m not saying there are, but if there are…” He thought he’d performed the ritual.

But for Klein, the editor of Vox, the ritual was not strong enough. Murray’s ideas are reminiscent of a grim history, in which pseudoscientific ideas about a hierarchy of humans were used to justify slavery or Jim Crow laws. For Klein (a low-decoupler, in Nerst’s taxonomy), you can’t simply take an idea out of its context like that. The context comes with it.

These two paradigms are very hard to square. Harris thought he was having a coolly rational debate in the philosophy-seminar style, so was baffled to find he was being accused of racism; Klein thought Harris was trying to sneak racist ideas in under an academic smokescreen, and couldn’t believe Harris claiming otherwise. Their models of the world were so different they just couldn’t understand each other. So obviously it descended into a massive online row with accusations of bad faith and racism.

That’s what I think was going on with the Dawkins tweet. Dawkins thought he’d performed the magic ritual – “It’s one thing to deplore eugenics on ideological, political, moral grounds. It’s quite another to conclude that it wouldn’t work in practice” = “By X, I don’t mean Y.” He is a nerdy, high-decoupling person, a scientist, used to taking concepts apart.

But many people reading it are not high-decouplers; they hear “eugenics” and “work” and immediately all of the history, from Francis Galton to Josef Mengele, is brought into the discussion: you can’t separate the one from the other.

'Eugenics is possible' is not the same as 'eugenics is good' By Tom Chivers

I think a lot of arguments in society come down to this high-decoupler/low-decoupler difference. And while I hope I’ve done a good job of putting the case for low-decoupling, I am very obviously a high-decoupler, so often I find myself thinking “but they performed the magic ritual! They said they didn’t mean Y!” and being really confused that everyone is very angry that they believe Y.

Dawkins, to my knowledge, never explained why he suddenly brought up eugenics out of a clear blue sky, but the word is in the news at the moment because Dominic Cummings hired the weirdo he wanted to hire, a man called Andrew Sabisky. Inevitably enough, the media has gone through his old social media posts and found various things he’s said, and he has since quit.

For the record: some of it is genuinely unsettling, for instance that “there are excellent reasons to think the very real racial differences in intelligence are significantly — even mostly — genetic in origin”. This is, I think, not true — I don’t know how you square it with the simple fact that poor black boys in the UK get better educational outcomes than poor white boys, for instance. And none of this should be seen as a defence of Sabisky’s hiring. (Watch me perform the decoupling ritual: will it work?)

But I thought a few of them were interesting from this high/low decoupling point of view. For instance, he described female genital mutilation (FGM) as a “moral panic”, because the actual numbers were low, so the risk to girls in the UK was pretty tiny. The full quote was “It is still unclear to what extent FGM represents a serious risk to young girls, raised in the UK, of certain minority group origins. Much of the hue and cry looks more like a moral panic.”

It seems fairly obvious to me that Sabisky is saying that FGM is rare in the UK – a view, incidentally, shared by at least one consultant obstetrician in the BMJ, who said “there is no evidence that large numbers of girls living in UK are having FGM”. He’s not belittling the impact itself.

Similarly, I’ve said before that claims about a wave of teen suicides are “absolute bollocks” and that the “epidemic of loneliness” is not real; that doesn’t mean I don’t think that suicide and loneliness are terrible things. You can decouple the frequency of the event from the seriousness of the event when it does happen. But for low-decoupling people, you can’t; by downplaying one, you are downplaying the whole package.

Similarly, Sabisky said that “women’s sport is more comparable to the Paralympics than it is to men’s”. But the context was that of Caster Semenya, a female runner who has an unusually high level of blood testosterone, and whether she should be allowed to compete in women’s sport. Sabisky is suggesting, as I understand it, that there is a need to draw boundaries around women’s sport in a way that you don’t around men’s, but you do around the Paralympics; if anyone could compete in women’s sports or the Paralympics, then lots of mediocre able-bodied men would win them and there would be no women’s sports or Paralympics left. The concept of “boundaries around the sport” has been separated from the idea of the sports themselves. But to a low-decoupler, it sounds, I think, as though he is saying they are inferior.

'Eugenics is possible' is not the same as 'eugenics is good' By Graeme Archer

Even his “eugenics” argument, in an interview with Laura McInerny in SchoolsWeek in 2016, strikes me as quite a separating-the-feelings-from-the-facts, decoupling-style situation. In fact he even says so, explicitly: “You have to separate yourself from what you feel and from what are the facts of the matter.” He asks whether parents should be able to screen IVF embryos, whether for disability or schizophrenia, or for intelligence. The former is not a million miles away from our current situation, where pregnancies at high risk of chromosomal disorders can be terminated if the mother wishes; the latter will probably be happening in China in a few years. The fact is that it’s possible; that doesn’t say whether it’s right.

Sabisky himself, according to that interview, seems to be against it: “He is personally uneasy about the ethics of many of the things he talks about and as a Christian — he married in church last year — he has moral views on the topics that may not be what people expect.” It seems to me that he is explicitly decoupling what he thinks is true, or what he thinks is effective, from what he thinks is right.

I don’t think, as some people do, that these remarks have been “taken out of context”, as such. I think that even with the context, lots of people would still assume that when he says “FGM isn’t a major risk” he means “we don’t need to care about FGM”. Similarly, Dawkins’s tweet wasn’t taken out of context: the context was all there, but the magic ritual didn’t work. It’s a translation problem: some people think they’re having a cold, rational discussion; other people are alive to the implications; there will be frequent occasions when the two groups will hear the same words and yet understand totally different things by them.

Again, to perform the decoupling-ritual one more time, none of this is to defend the hiring of Sabisky — who, full disclosure, I met in 2017 and interviewed for my book. It wouldn’t surprise me, to decouple again, if he was a useful person to have around government: he is a “superforecaster”, which means that of the 20,000 people making predictions about the future for the Good Judgment Project, he was one of the 150 who scored best for accuracy. (Read a bit more about that here, if you like.) I suspect having people who are really good at predicting the future is useful, but that is decoupling his abilities from his views, and maybe that’s not a good thing to do.

But I think the decoupling thing makes me understand a bit more why Dawkins’s tweet got people so angry. Sometimes the ritual fails, and the spirits break through the warding circle.