Which is the better measure: customary or metric?

Should we have customary measures, or metric ones? What would make one better than the other? A remarkable thing to observe is how hot people get under the collar over measurements.  At one level it seems like the same sort of issue as whether you call something a swede or a turnip or a rutabaga. I mean, it might be confusing, but who cares? Different strokes, different folks. Why would you legally preference one over the other, as happened with metric over customary measures in Britain? Why would you be outraged at not being allowed to sell solely in pounds and ounces, or at the Government putting customary measures back on a level pegging with metric? Yet many people are, and furiously so – read opinions columns, read Twitter. These great emotional geysers must necessarily tap deep wells.
 
We can more or less take people at their word, I think. Here are the most typical explanations I hear, just in common conversation: “metric is more rational, it’s easier to use” vs “customary is familiar and well-worn, it feels human”. Let’s boil these down, or extrapolate them, or something.
 
The strengths of metric are that it is more “rational”, and easier to use. The latter can be summed up by saying that base 10 is a wholly regular for multiplication and division, and that using it across different areas of measurement (length, weight, volume, etc) is easier to learn than a mixture of base 12, 14, and 16. Well, base 12 and base 16 are both pretty good – arguably more useful than 10 – but I think we can allow the general point.
 
“Rational”, of course, is actually a word meaning something else, here. It’s aspirational, not simply rational. The metre was the result of a French Revolutionary project, based on a fraction of the earth’s radius, or at least on an estimate of that – now known to be inaccurate. Yet the symbol remains – even the flaw might be seen as an eloquent testament to the ongoing process of scientific refinement, of rationality, of the humility of pure reason. The metric system – metre, metric, from Greek metreo, I measure, Greek the language of reason and science – declares the total comprehensibility of the world, of the prospect of human mastery over it, of progress.
 
Those who prefer customary measures will often think of them as like a well-worn stairpost in a family home, smoothed by generations; like family photographs so familiar as to be impressed into memory. The pint is the shape of a particular glass (since 1913!), the particular measure, the pub or bar, the chain of memory linking back to every “Royal Oak” founded in thanks to God after 1660, every “Marquess of Granby” after 1770. Every old soldier sitting in his pub, endowed by the bald-headed old soldier, drank and served this measure; the rum measures served to the victorious survivors of Trafalgar were measured in the same (well, actually, in quarter-pint measures, gills, but you get the point).
 
Indeed, many of the measures feel measured not in terms of universal absolutes, human mastery over nature, but rather in terms of smaller, humbler measures. How far is the human stride? What is the length between thumb and forefinger? How much ale fits into a round-handled drinking jar? (Okay, that last one is speculative! But probably right. These things stretch back into the mist.) These are, in the general sense, actually quite easy to teach and learn; these connect physically, they resemble something (your grandfather’s hand, the comfortable glazed jars on the shelf). They are not consistent of themselves, of course – they have to be codified to be consistent, as we in fact have codified them – and they will vary throughout the world, but what matters is that they work in the place they exist to measure. This task they accomplish.
 
One might consider this all easily resolvable. Metric can serve as a measure in science, if it suits scientists – they say it does – and it can be a universal translator for measures, a Rosetta Stone to turn lakhs into shillings, an instrument of international trade. Customary measures can be happily used at home, uninterfered with by any Weights and Measures Acts.
 
Yet this simply does not satisfy some. One or other must totally triumph – and in our day, the side comfortably most aggressive on this point are those who do not simply prefer metric, but who are devoted to its propagation. To put customary and metric measures on level pegging, we are told, is to throw the UK back to the 1970s; it is “weaponising nostalgia” (blasting shillings from a shotgun, launching lbs from a bombard); it is crypto-imperialism. This is all ridiculous, of course, and the vast majority of metric supporters would not adopt it, but why is it used by prominent public figures? What causes this moral spasm?
 
How we measure the world is how we see the world, and for the diehards, there is only one window in the whole stately home through which to view things. What is at stake – why such rhetoric seems justified to the arch-metrician – is that the Revolutionary measure represents the Revolutionary spirit, the Revolutionary achievement, the conquest of superstition and tradition and the triumph of the human spirit. Why would you not fight for that? Of course any attempt to undermine or reverse that progress must be halted, crushed, obliterated. The pint in the pub, the measurement in ounces, the similar but flawed yard over the metre, all must be seen as counterrevolutionary, as enemies of the people.
 
It is ultimately existential, as ridiculous as that might seem. That it is existential actually, I think, the puzzled indifference of the typical conservative. You say to the philosophical conservative that this measurement helps the scientist, or that translation into it serves the purpose of trade – very well then, that is a prudential and wise purpose. The origin of the measurement is of little concern. Variety is a conservative value, the fitting of different tools to different tasks. The progressive believes that the most elegant of field tools, the Dutch hoe, is for digging holes and removing branches; the conservative turns to the clumsier spade and the fault-prone lopper for these tasks, because they actually do the job. Thus the conservative can reconcile to the use of metric as the progressive cannot to customary measures.
 
Yet the conservative can never be drawn away from the worn stairpost and the old pint tankard. These may not seem rational to Robespierre, but they are totally reasonable; they are useful things and loved things, and one never throws away either. The conservative looks at the yard and thinks: why is my stride something like a millionth of the earth’s radius? What order and what plan has designed my body like that? How do I, mere clay, fit into this enormous cosmic order that is so measurable, so reasonable? And so the conservative finds a little treasure in the French Revolution, in the monstrosity that set the world to an inferno not yet quenched. The conservative values the yard more for the metre, not less.
 
The question of which of metric or customary measures is better is one that cuts beyond the first responses to the bifurcation rending Western civilization. No simple formula can conclude the debate; in the final accounting, it ties to the ultimate issue of existence, whether man exists in a cold, indifferent nature, aiming to conquer and subdue it – or whether man takes part in an ancient and orderly dance, a minor but privileged participant in the great work of creation.