parsimonious

A colleague noted a sentence from a book her son the veterinarian was reading:

This suggests that one of the functions of burying faeces is to minimise the likelihood that the olfactory information they contain will be detected by another cat, although hygiene may provide a more parsimonious explanation.

She wondered what word they meant to use that they had mistakenly confused with parsimonious. After all, parsimonious is a rather prodigal way of saying ‘stingy’ or ‘miserly’. And what on earth would a penny-pinching or mean-spirited explanation be?

But a more parsimonious explanation for the choice would be that the word has a proper technical use in that context. That is also the correct explanation. In science, the law (or principle) of parsimony is just that you shouldn’t invoke any more causes or forces than you need to in explaining something. You might say “parsimonious” is the sound of someone shaving with Occam’s razor.

Think of explanatory factors as like money and be sparing in your spending. A parsimonious explanation is one that is pared down, has minimal parsley, needs minimal parsing. If you see hoofprints in the snow, think horses, not zebras; if you see a butterfly, do not assume it is a Parnassius simonius visiting from the Pamir Mountains.

Parsimonious – and its source noun parsimony – did not, after all, originally have a negative tone. It referred simply to frugality, thrift, economy. It comes ultimately from Latin parcere ‘save, spare’. It just happens that while people like money saved by them, they don’t so much like money saved on them. No one wants to have to say, “Please – some more?”

So we have a justification for calling something parsimonious if it’s simple clean and free of unnecessary parts. Another word used for equations and algorithms that are uncluttered is elegant. An explanation that is elegant is also parsimonious. Compare that to everyday life, where furnishings, clothing, or catering can be parsimonious or elegant but, in most people’s eyes, certainly not both!

How do we explain this? Well, elegant comes from Latin meaning ‘carefully selected’. In machines and alogrithms, that means an efficient and direct use of as few pieces as possible to maximum effect. In everyday life, that means simply the best, the finest. The one values mental mastery; the other, socioeconomic mastery. One privileges the parsing, and the other privileges the purse. So be particular when picking your parsimony.

One response to “parsimonious

  1. ““parsimonious” is the sound of someone shaving with Occam’s razor.’

    That’s a nice way to express it. I’ll have to use that during my stat and research methods lectures. (citing this blog, of course).

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