Alex Steer

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The plausibility effect; or, if it sounds true, it must be true

809 words

Ben Goldacre, in his excellent Bad Science column in the Guardian, recently examined what he calls the plausibility effect: the tendency for people to believe statements based on the perceived credibility of the person making them, unconnected to any evident truth value. If this is true in various branches of science and medicine, it is just as true when it comes to people's reactions to words - and, in particular, to opinions on the origins of words and their correct usage.

Sometimes people develop unusually strong attachments to their favourite stories about the origins of words, to the point that they don't much like being told, for example, that posh is not an acronym for 'port out, starboard home', the f-word never stood for 'for unlawful carnal knowledge' (or 'fornication under consent of the king'), and the window tax did not give rise to the term daylight robbery. I don't make a habit of this sort of mythbusting, by the way, unless people ask: that's probably the third quickest way to use language to lose friends and alienate people. (The second is to go around correcting apostrophes; the first is to correct people's grammar while they're talking. Or possibly instituting a language policy to marginalize a whole section of society. I can't decide.)

Even so, when people do show off their favourite etymology stories to linguists and lexicographers, and those linguists and lexicographers sigh a bit wearily and say that it's an old story, but there's no data, people often give the same reply. This is: but you can see how it could be true, or some variation thereof.

This is the plausibility effect at work in a rather strong way, being used as a kind of defence. There is good reason, the plausibility defence says, for thinking that an explanation of a word's origin is true, because it sounds like it could be true. That defence, in itself, sounds superficially plausible. But, when you think about it, it doesn't make sense.

Most explanations for the origins of things will, in the absence of evidence and context, seem plausible. That's the whole point of explanations: they allow us to make sense of things, so they must at some level be sensible. The acronym explanation of the 'f-word' is much better explanation of its origin than the explanation which says that the word appeared in the late Middle English period of the language and its etymology can only be guessed at. The latter is a terrible explanation. Unfortunately, it's the one that's supported by the evidence.

Evidence is, after all, annoying: it gets in the way of a good explanation. That's why false explanations are neater: they can be comprehended without recourse to the messy details of the evidence, and so their narratives are cleaner and, superficially, do a better job of passing the plausibility test. This does not, it should be added, make them correct. It makes the plausibility test a very bad way of assessing the origins of words. This is a variant of the same 'easy narrative vs. evidence base' argument which, in much more controversial form, keeps the debate over intelligent design rumbling on. Intelligent design not only lacks any evidence in its favour, it is methodologically flawed to the point that it cannot be considered science. It relies entirely upon the plausibility effect, and the ease with which this can be applied in contexts - like biology, like historical linguistics - where seeking out and analysing the evidence takes a lot more time and effort than believing a good story. (An important caveat is that the ID debate, to a greater extent that etymological controversies, is fuelled by arguments in which some 'evidence', often quite detailed, is marshalled. Nonetheless, the distinction between good science and bad lies in the willingness to have one's evidence overturned by other, better evidence. This is good science. Bad science frequently involves being so convinced of the plausibility of one's initial explanation that one discounts any good evidence to the contrary instead of revising one's theory.)

If you're interested in the relationship between where words actually come from and where we like to think they do, start with Michael Quinion's excellent Port Out, Starboard Home, which should be enough to make you wary about plausible etymologies for the rest of your life. Which means, in turn, that you will be saving the sighs of linguists and lexicographers by not passing around etymological fairy stories. Which means that you will not make enemies of linguists and lexicographers. Which is good: they're not a powerful lobby, but they write very long letters.

# Alex Steer (28/07/2008)