posted 3rd February 2026
‘Jack, I’ve booked a dentist’s appointment for you on Tuesday.’
‘When?’
‘Nine o’clock.’
‘But, Mum, then I’ll have to miss Maths!’
‘It’s all right, I’ll email the school and get permission for you to be absent, you won’t get into trouble.’
‘But if I miss Maths, I’ll fall behind … and if I fall behind my marks will drop … and if my marks drop I won’t get as good a GCSE grade … and if my GCSE grades drop I won’t be able to get into university … and then I won’t be able to get a job … and then I’ll end up living on the streets … and someone might attack me one night … and then I’ll be dead before I’m twenty …’
See what Jack did there?
He started with a small problem (missing Maths) and assumed that it would inevitably lead to a much bigger problem (being murdered). He implied a whole set of inevitable consequences from the action of missing Maths, none of which he proved to be inevitable.
This is known as the slippery slope argument. It posits an inevitable progression towards an extreme consequence for an action without proving that this consequence is inevitable or even likely. It is a bad argument, almost always made for the opposition.
Say the motion is: ‘This house would abolish GCSEs.’ An opposition speaker says:
‘If we abolish GCSEs, students in Years 10 and 11 will have no motivation to study. As a result, they will pay no attention in class. No one will learn anything, and students will leave school without basic literacy and numeracy skills. They will not be able to find work, and will have no choice but to turn to crime, and the murder rate will go up.’
This starts with a strong argument against abolishing public exams; the benefit of the level of focus and motivation these exams inspire in students, and the harm of losing that focus and motivation. Unfortunately, it then goes on to undermine that argument by greatly exaggerating the harm.
What could the speaker have done better?
Focus on a realistic, likely harm from the action proposed for the motion, for which there is some evidence. In this case, they could have said:
‘Once the pressure of public exams is removed, many students lose motivation to study. There is an example of this is at A-Level. Students who have been given unconditional offers for university often work much less hard, and as a result achieve lower grades than they are capable of.’
This is a much stronger argument, because it is more plausible. If Jack had just told his Mum he’d rather not miss Maths because they’ve got a big test coming up soon, so could she please see if the dentist has any appointments on a Saturday, she would be more likely to listen to him.
How should you respond if your opponent uses the slippery slope argument?
It enables you to avoid having to deal with the more likely harm, because you can focus on rebutting the less likely harm. Point out the implausibility of the harm and the lack of evidence offered for it, and then steer the argument back to your terms:
‘While some students may temporarily lose some motivation in the absence of public exams, the great majority will still be mature enough to see that it is not in their interests to disengage from school. It is highly unlikely that any but a very small minority would disengage to the extent that they would leave school with no skills, or will turn to crime. It is actually more likely that students will be more motivated, as lessons will be more interesting and stimulating once they no longer have to focus on boring, repetitive drilling for exams …’
To sum up:
- If you’re the opposition, don’t exaggerate the harms that the action proposed by the motion will bring.
- Focus on likely harms which are easier to prove.
- If your opponent exaggerates harms, point out how unlikely they are and then return to the benefits of your proposed action.
