A writer should never not use no double negatives

A recent article reporting a restaurant’s threat to sue someone for a poor TripAdvisor review set me grumping:

Why would customers who have not been unimpressed – ie, who have been impressed – be threatened by lawyers? A GCSE student would be taken to task for tripping themselves up with their own double negatives. And this is a professional journalist with his own byline on a major national paper.

It did set me thinking though. I remember being taught that a double negative was inherently and invariably an error. The two negatives ‘cancel each other’; they are therefore redundant, and should be removed.

But how about…

The performer has turned up, the crowd are baying for fun, but she doesn’t feel too hot. Shivering sweats, dicky tummy, achy joints: doesn’t really want to go on at all. But these people have come a long way, paid their money: she has responsibilities to her fans. She can’t not go on.

Does this mean the same as ‘She can go on’? Clearly not. The double negative expresses something quite different: something more akin to ‘she must go on.’

I suspect the unyielding prohibition on double negatives shares its roots with the equally wrong-headed insistence on avoiding splitting infinitives: a grounding in Latin, and the attempt to force English into its hard, logical, almost algebraic straitjacket. As misguided as it is snobby. We are not Ancient Romans, and our language doesn’t work quite the same way.

Mind you, doesn’t not mean a Daily Mirror journo shouldn’t not be able to cope with the rules it doesn’t not have though. Do it?