The claim is often made by last-ditch defenders of miles, feet, pints and acres that “Imperial units are natural whereas metric units are artificial”. In the first of an occasional series of articles on “myths, misinformation and fallacies” used by opponents of completing metrication, we examine this claim.
A list of such myths is summarised in a webpage on UKMA’s main website at this link entitled “Briefing note for UKMA representatives”. This note arose from a discussion at UKMA’s 2012 annual conference about the abysmal standard of debate heard on local radio phone-in programmes. The original intention was (and remains) to help UKMA members and supporters to make the case in radio and television interviews, in newspaper correspondence and online.
In the coming months we shall be discussing particular arguments from this list and opening them up to readers of MetricViews. This week we look at the claim that:
“Imperial units are natural whereas metric units are artificial”
This claim is a favourite with defenders of imperial units. It is argued that the foot approximates to the size of the real foot at the end of your leg, and therefore it is a “natural” unit that people can relate to. Thus it is claimed that it is easy to estimate short dimensions – e.g. the width of a room – in feet. Similarly with an inch, which corresponds (allegedly) to the width of a thumb. Likewise a “hand” … and so on.
George Orwell is often prayed in aid, as his satire on life in a totalitarian state in “1984” included the grumble by the old man whom Winston Smith meets in the proles’ pub: “A ’alf litre ain’t enough. It don’t satisfy. And a ’ole litre’s too much. It starts my bladder running.”
Another somewhat far-fetched claim is that it is easy to estimate by hand the weight of, say, a bag of potatoes in “natural” units (pounds), but less easy in “artificial” kilograms.
Yet another claimed example of a “natural” unit is the acre. This is (apparently) easily visualised since it is roughly the area of land that a horse can plough in a day.
None of these claims can withstand even the most cursory examination.
If a measurement unit is to be of any practical use in (e.g. in shopping, building design or regulating speed limits) it has to be precisely defined – and defined in terms of some objective standard which can be referred to. Yet, as soon as it is precisely defined, it ceases to be “natural” and becomes arbitrary (or “artificial”). This is to ignore the obvious fact that adult human feet are of varying lengths, generally in the range 220 – 290 mm, and rarely as long as 304.8 mm (the official definition). Similarly with thumbs, hands etc.
Orwell was of course parodying – not endorsing – the old man’s preposterous belief that he could tell the difference between a pint (568 mL) and half a litre (500 mL)of beer when poured into a pint mug. Later in this passage, he narrates that “Winston went to the bar and came back with two more half-litres. The old man appeared to have forgotten his prejudice against drinking a full litre.” (To get the full context, you can read chapter 8 of the novel online at this link.
(For a discussion of the advantages of using lined beer glasses rather than brim measure “pint” glasses that deliver short measure, see this link).
Horses are rarely used in the UK for ploughing these days (except as a competition sport), so sights such as in the photograph below will be unfamiliar to most British people (it was actually taken in Slovakia, which – inexplicably – does not use the acre).
So one wonders how many people can actually visualise the acre – or indeed have any idea how big it is. (Answer: it is a furlong multiplied by a chain. This then gives the conveniently round number of 4840 square yards – or 43 560 square feet if you prefer).
Of course the claim to “naturalness” is nonsense. Imperial units are only “natural” in the sense that it is “natural” to speak English. In other words, it is what you are brought up with, what you learn from your parents, siblings and peers. In countries where the metric system is well established it is equally “natural” to use metres, kilograms and litres.
Ironically, a case can be made that metric units actually are “natural” in the sense that, with the exception of the kilogram, they are defined in terms of constants of nature. For example, the metre is defined as the distance travelled by light in a vacuum in a tiny fraction (1/299 792 458) of a second. And a second is defined in terms of a particular energy level transition frequency of caesium atoms.
Even more ironic is that, since the Weights and Measures Act 1985, the surviving imperial units are defined in terms of metric (SI) units. Thus in reality an imperial foot is the distance travelled by light in a vacuum in 1/983571056 of a second.