Collective punishment is the punishment of a group for the actions of an individual. The logic is that if one terrorist (or freedom fighter) launches some kind of attack on an oppressor, then reprisals will be visited on his or her community. The threat of such retaliation is intended to quell civil disobedience before it even occurs through peer pressure: if I know you are planning something the authorities will object to I will seek to persuade you not to carry out your plan so that I and the rest of our community will be spared the punishment which should rightfully be perpetrated just on you as the culprit.

Collective punishment has a long history. In the second century BC, Chinese emperor Qin Shi Huang instigated the practice of punishing the most serious of crimes with nine familial exterminations – everyone in the perpetrator’s extended family (classified into nine distinctly different groups) would be wiped out. In Texas, 1906, two white soldiers were shot. No one knew who was responsible but they were fairly sure whoever it was must have been black, and so 167 black American soldiers received dishonourable discharges.

It can be a pretty effective system. The British army used collective punishment during the Boer War as did the Nazis and Stalin. There’s one minor drawback though: it’s a war crime specifically forbidden under the fourth Geneva Convention.

Article 33. No persons may be punished for an offense he or she has not personally committed. Collective penalties and likewise all measures of intimidation or of terrorism are prohibited.

Today I picked my daughter up from school. We were in a bit of a rush and I was irritated that she was almost 10 minutes late in coming out of her classroom. When I expressed my irritation, she told me her teacher had kept her behind. Normally she’s pretty well-behaved so I asked what she’d done. Nothing! Miss keeps us all behind every time one of the boys speaks.

Despite wanting to storm in and express just how unfair this practice is, in a rare moment of wisdom I managed to restrain myself. You see, I’ve been there. When a class is giving you a hard time one of the few deterrents available is to keep them all behind after a lesson. Naturally no one wants to punish well-behaved children, but in the hurly burly of the classroom it can be difficult – nay impossible – to always correctly separate the guilty from the innocent. And so it’s easier – and, we tell ourselves, fairer, to punish everyone. But it’s a particularly stupid thing to do, for three reasons.

Firstly, on the whole, kids that mess about in lessons don’t actually care if their well-behaved peers are also kept in late. In fact, they tend to prefer it; it means they’re not alone to face the consequences of their actions. So it really doesn’t work as a deterrent.

There are bigger problems however. Collective punishment can create a perverse incentive to misbehave. If you know you’re going to be punished despite not having committed a crime, you might as well commit the crime – you’re paying for it after all. As a child, I used to take this view in disagreements with my younger brother. He’d tell me that if I didn’t do what he wanted he tell my mum I’d kicked him in his bad leg. Unmoved, I would then continue as before. He’d then shout, “Muuum! Agghh. David’s kicked me in my bad leg!” In the moments between his scream dying and the approach of my mother’s thunderous footsteps I’d think, what the Hell, and kick him.

The third problem with collective punishment is that it erodes the relationship between the teacher and the good kids. Even if they choose not to misbehave – and they’ll always be some who make the right choice (My daughter is fortunate to have inherited her mother’s genes!) – they’ll still feel the sting of injustice. They know their punishment is unfair. Of course they’ll resent the real culprits, but they’ll resent the teacher more. When authority appears arbitrary and iniquitous, over time more and more children tend to drift into mild and tacit naughtiness. Their sympathies shift and before you know it the bad lads are cast as Che Guevara and you, the well-intentioned teacher find yourself playing the Cuban dictator, Batista.

Whenever I’ve seen frustrated teachers deploy collective punishment, it’s usually a last, desperate act. The most frustrating part is that it’s actually very easy to avoid. Here follows my very simple solution to dealing with unidentified troublemakers in a way that doesn’t punish the compliant. Firstly, you know who they are. You might not have caught them in the act, you might not be able to prove it beyond reasonable doubt, but you know. After all, they’ve got form. You also know who is without sin. Some children never misbehave, whatever the provocation. It is never fair or acceptable to punish these poor, put-upon kids.

On those occasions (and there have been many) when I had to write minutes on the board to persuade errant pupils to follow basic instructions, when the end of the lesson came I would let the innocent go. Everyone would be made to stand quietly behind their desks and those I knew to be pure at heart would be allowed to leave. I would then launch into some variant of my ‘disappointed’ lecture. At this point there would be some pupils who tried the line, but it wasn’t me, or, but I wasn’t as bad as Tom. In response I would either say, Well, it is now, or, I know that, and the sooner I’ve finished speaking the sooner you will go and I will be able to speak to Tom privately. Now the next layer of minor miscreants can be released. They might not have done much, and they might not have been involved this particular time and you have shown you realise they are not the real problem.

Sooner or later you’ll be left with the hardcore. Now you can issue whatever punishment their behaviour seems to merit and is in line with your school’s behaviour policy safe in the knowledge that justice has prevailed. The innocent know you are a fair and even-handed judge and the guilty know they cannot hide behind the collateral damage of their peers.

Next time you’re tempted to stoop to collective punishment, remember there is an easier, fairer way.