We need to talk about “common sense”…

No two words in the English language have done more damage to the cause of human rationality than “common sense”.

(At least, I would like to simply assert that as some opening rhetoric/hyperbole, as quantifying that last sentence to prove it might be a little difficult and more trouble than it’s worth.)

Everyone’s heard of “common sense” before. There’s 62 million results for it if you bung it into Google, it’s probably been spat in your face since forever.

“We need more common sense!” you’ll hear from politicians as they begin to dismantle complex laws built up over time, or “you have no common sense!” you’ll read in a backwater comments section as if it refutes actual studies and research, “this is just common sense” says someone in support of their argument.

But what does it mean? Let’s run to Wikipedia and grab the first line:

Common sense is a basic ability to perceive, understand, and judge things that are shared by (“common to”) nearly all people and can reasonably be expected of nearly all people without need for debate.

Okay, not bad. We can all agree on that. And if you asked anyone who made an appeal to “common sense” this is probably what they’d cite as their definition.

Hopefully, though, you shouldn’t take too much convincing to know that there’s a big difference between what people say that they mean, and how they act out what they mean. Someone who is adamant that Jesus will protect them at all times will still look both ways when crossing a busy road. Someone with a stated mistrust of science and doctors will still knock back aspirin and paracetamol like it’s going out of fashion to cure their headache. Someone will proudly proclaim “I’m not a racist!” and then proceed to cite The Bell Curve and argue that Asians are all good at maths and that can’t be racist because it’s a positive thing. An intersectionalist will decry overgeneralisations, racism, assumptions, and promote the need to assess everyone as an individual that’s a sum of all their experience – and then rant about how terrible white people all are. The list goes on.

So it shouldn’t take too much imagination to realise that when someone says that “common sense” means “something obvious to all of us”, they might not really use it that way.

How is it used? As in, actually used by people who say it, and what do they want to achieve by saying it. Words themselves don’t have inherent meaning, but they do have use-cases and an intended effect by the users.

It doesn’t take too long to search a right-wing tabloid for examples of the phrase. That hardened bastion of “common sense”, The Daily Mail, is full of them. Lord Falconer proposes “common sense” human rights – doesn’t seem to suggest anything, just uses it as an excuse to throw out other ways. “She’s intelligent but doesn’t have common sense” – again, to dismiss someone or some other way. “Insult to common sense” – said about laws to stop workplace harassment.

These are random-ish examples, but in each one there’s not much reasoning to be found that’s “common to everyone” as the definition suggests. There’s a lot of “common to everyone who thinks like me” as a matter of course, but not much common to everyone. Everyone who thinks like a Daily Mail reader will certainly think lewd and sexist comments toward barstaff is acceptable, because “common sense” says that’s okay because at least it’s not really lewd and sexist. But I don’t agree with that conclusion, it’s not obvious nor self-evident to me without need for debate. I think it’s fine to stick a recommendation, regulation or law in place that says “that’s not acceptable”. That’s why laws exist – to tell people that something isn’t acceptable when they may well think it is. Do I “lack common sense”, or do I just have a different view of the world and would like to make it better for people? It seems that the “without need for debate” section of that Wikipedia definition should be bold, italic, underscored and in a much larger font-size than the rest of the definition.

I’ll leave you alone to stick things like “climate change” and “common sense” into Google to fill out those examples for yourself – it’s just too depressing otherwise.

Let’s look at another particularly insidious example. You’ve probably read a few things like this before – “Common Sense Died Today!” reads the usual headline, though there are many variants.

I want to use this example to convince you that while “common sense” supposedly  means “something obvious agreed upon by everyone”, it’s really used to mean “this heuristic that I’ve used for years and will now uncritically apply to a new situation whether it’s applicable or not” in addition to the “we won’t debate this” part.

This reflects how humans actually think – our brains are huge stores of prior experience and one of the reasons we can think and act so quickly (and sometimes efficiently) is that we look to these old experiences to help us deal with new ones. I don’t need to calculate the exact way I need to move my spine to counter-balance on one foot every time I walk – my brain is simply looking it up from prior experience. That’s what things like “practice” leads to.

“Common sense” sounds like it fits this heuristic-based description quite well, but all good skeptics and rationalists should recognise that doing exactly as you did before sometimes isn’t a good idea. It might work in 90% of situations, but applying those hard-learned rules to that remaining 10% could end pretty badly. Yes, we can live with those odds, a few screw ups is a small price to pay for efficiency the majority of the time – but I want to argue that if the only reason and rationale you give is “common sense” or “we’ve always done it like this”, then you’re far, far more likely to be operating in that 10% of situations where it’s not going to work. Because, of course, people who are right just give a reason that they’re right – they don’t need to say “this is just common sense” and refuse to give further reasons.

Anyway… back to the “death of common sense” trope. This is a very common meme associated with “common sense”, and I want to unpick that one I linked to in particular, and hopefully convince you that it is, in fact, utter nonsense…

Common Sense lived by simple, sound financial policies (don’t spend more than you can earn)…

Right from the off we have something that’s actually very much wrong – or at least painfully oversimplified to the point of being effectively useless. Everyone has to accrue some form of debt to get things done. No-one really buys a house in cash, few even buy a car outright – we all spend more than we earn, usually as a form of investment so we might earn more later. In fact, businesses run on this principle pretty much exclusively.

Reports of a 6-year-old boy charged with sexual harassment for kissing a classmate…

This is uncited bollocks, since it’s unlikely anyone would be able to charge a minor for sexual harassment – not because it’s “common sense” but because they don’t have legal capacity to be responsible for their actions. But mostly, damn fucking right that’s sexual harassment you stupid fuck.

It declined even further when schools were required to get parental consent to administer sun lotion or an aspirin to a student…

Further demonstrable nonsense because, get this, you’re their teacher not their doctor. It sounds like great “common sense” to just hand out painkillers to kids, but you don’t know their medical history. You don’t know what else they’re taking that could react with it. You don’t know their allergy information – and if you’re dealing with a school kid you can’t trust them to reliably tell you. What? The kid complains of a headache and wants teacher to give them paracetamol – you sure they didn’t take some before arriving at school? They go to a lesson an hour later, ask for more… before long this “common sense” has caused a kid liver failure.

Another version of this bit talks about elastoplasts – yeah, great, risk giving someone a dangerous reaction to latex because your “common sense” overruled actual medical responsibility.

…but could not inform parents when a student became pregnant and wanted to have an abortion.

Also not true. Generally speaking, teachers have no legal obligation to inform parents… nor do they have a legal obligation to confidentiality. But are you trying to imply that “common sense” dictates that you must go behind the back of a student you have a duty-of-care over in order to tell their parents about something without discussing it first? I really don’t want to be seen dead doing this “common sense” thing.

Common Sense finally gave up the will to live, after a woman failed to realize that a steaming cup of coffee was hot. She spilled a little in her lap, and was promptly awarded a huge settlement.

Randy Cassingham’s True Stella Awards is no longer active, but catch the page while it’s still up to learn while this one true but misreported. The full list of others nonsense lawsuits that have been fabricated can be found here, in case you spot one in a variant of this meme.

Okay, so a lot of the above is wrong on a factual basis – yet they still are, to a degree, intuitively correct. People will certainly go around pretending some of the points sound reasonable. But reality is far from intuitive. First-aid (particularly mental health first-aid) is hugely counter-intuitive. “Oh, you’ve broke your arm, clearly… here, give it to me while I yank it about and put it into a splint… stop screaming! This is just common sense that you need to do this!!” – erm, no, if someone has broken a bone and they’re cradling it, it’ll be literally in the most stable and comfortable position you can get it in, so much for common sense. “You want to self harm? NO! Stop that! You’ll hurt yourself!!” someone will scream, citing that it’s “common sense” to protect someone – the reality says if you remove someone’s stabilising mechanism you’re likely to do more harm in the long run. Someone might say “but you’re describing common sense!” – but, no, I’m not. This isn’t common. These things are genuinely counter-intuitive. They’re not well-known facts. And I certainly won’t defend them by saying “it’s just common sense”.

Exceptions come along far more regularly than you might expect – and, remember, if your main reasoning is intuition and “common sense”, then you’re probably dealing with one of those exceptions.

To go back and answer a previous question – how is it used? What is the intention behind someone saying “common sense”? Far from being an example of reason, it seems to be there principally to rebuke it – screw your argument, it’s common sense! It seems to be used to defend the status quo – a six-year old kissing a classmate without their consent isn’t sexual harassment, common sense says so! It’s there to shut down reason, with the implicit assumption that someone proposing something lacks the fabled “common sense” and so is, deep down, just stupid just because.

So, instead of appealing to “common sense” to defend something, how about appealing to an actual reason. You should be able to give one if you happen to be right. After all, isn’t that just common sense?