I’m learning to drive. I own a car (K-reg VW Golf 1.8, red, since you ask). These facts combined sort of vaguely qualify me to make the following post.

There is an advert on TV at the moment (these days, that is, not literally now) about car tax. Does that make it more of a public information / governmental threatening short film?

In any case. The shot opens on an expired tax disc in the window of a car. We can tell it’s expired because it’s dated 1953 or something, and signed by Clement Atlee. A menacing voiceover says that some people don’t bother to tax their car, but that that never hurt anyone, right? Wrong, clangs the VO, as the camera zooms out to reveal the full car, embedded into a wall, because if someone can’t be bothered to tax their car, then they probably won’t be bothered to book it in for an MOT. And, says the voice, as the camera zooms out to reveal policemen milling about in a scene-of-crime sort of way, if they can’t be bothered to get it MOTed, then they probably won’t care if it doesn’t function properly. Ominous shot of empty pushchair beside car wreck. Then the message: tax your car or face a fine. DVLA. Rah rah rah.

Is it just me or does this seem like an absurd stepping stone path of conclusions? If you don’t tax your car then the next step is mowing down small children on the road? I can see a flimsy logic behind it all - Someone who breaks one law may well break others? Someone who breaks one law doesn’t care about laws? - but it doesn’t necessarily follow through as neatly as they presuppose. Someone who breaks one law might well break others, but it would seem absurd to say “a person who doesn’t tax their car will probably break in through next door’s bathroom window and threaten the old lady who lives there with a wrench.” Surely the key message is: “Not taxing your car is illegal. If you don’t do it, we’ll fine you” rather than “no tax = murderer!”

If you have a cigarette, then you’ll probably smoke a joint. And if you have a joint then you’ll probably develop a heroin habit. And if you have a heroin habit then you’ll likely end up on the streets every night and robbing your local branch of NatWest just to pay for your next rock of crack. Or something.

What’s the name for the kind of logical argument which requires you to assume (or accept) a first proposition is true in order to make a second logically true?