Given Poland’s history of pioneering mathematical logic, it came as something of a surprise to come across a serious category error during my brief brush with the country when I flew last week from Sofia to Prague, via Warsaw.

A ‘category error’ is a philosopher’s way of identifying a particular type of nonsense, the ascription of an attribute to something to which it cannot in fact belong. ‘Readable grass,’ might be an example, or ‘friendly eggs.’

As Wikipedia puts it: ‘A category mistake, or category error, is a semantic or ontological error in which things belonging to a particular category are presented as if they belong to a different category,^[1] or, alternatively, a property is ascribed to a thing that could not possibly have that property. An example is the metaphor “time crawled”, which if taken literally is not just false but a category mistake. To show that a category mistake has been committed one must typically show that once the phenomenon in question is properly understood, it becomes clear that the claim being made about it could not possibly be true.’

A contradiction is another kind of nonsense, I suppose, but I like this illustration anyway and I can’t find an image that aptly illustrates a category error.

It was a miserable late afternoon in Warsaw. The cloud base was a mere ten metres above the tarmac. It was a relief to get down safely.

‘Welcome to Frederic Chopin International Airport, Warsaw’ the pilot said.

And that was it, in case you missed it. That was the category error.

I think of the Nocturnes – wistful, romantic, delicate, nostalgic – and then I look at the grey slabs of concrete, the ugly terminal buildings, the machines, the dirty snow. Naming the airport after Chopin will never make it nice. Listen and look.

Nocturne Opus 20 in C Sharp Minor