Changing a country's measures costs more than the tidiness it buys

The argument

The second argument for imperial does not claim the units are elegant; it claims that replacing them is expensive and that the expense falls on people who gain nothing from it. Where a country uses imperial measures, those measures are embedded in things that are costly to change: road signs and speed limits, land registries and property deeds, the sizes of pipe, timber, fastener and fitting held in every warehouse, the tooling that makes them, and the working knowledge of everyone in the trades. Proponents argue that a changeover does not simply substitute one label for another but obliges an entire supply chain to be re-specified, re-stocked and re-learned at once. They also point to the transition itself as the dangerous part. During a changeover the two systems run side by side, and that is when measurements are misread, parts are ordered in the wrong scale and tolerances are missed. The argument is that a country with a working system of measurement should weigh the risk of a long period of ambiguity against whatever advantage the new system offers. Set against that, proponents say, the benefit of metric is mostly arithmetical convenience, and arithmetical convenience is what calculators, spreadsheets and conversion tools now supply for nothing. Where a figure has to be converted, software converts it. What cannot be bought so cheaply is the accumulated fit between a population and the units it already thinks in. Proponents conclude that the sensible course is to keep the system in use, let specialist fields adopt metric where their own work requires it, and decline to impose a general conversion whose costs are certain and whose gains are marginal.

Premises

Counter-arguments

Critics answer that this is an argument against converting rather than an argument that imperial is better, and the two are easily confused. Every country that has converted faced the same embedded stock and the same period of dual running, and those costs were paid once while the benefits recur for as long as the system is used. They add that the cost of not converting is simply paid in a different currency: every part, drawing and dataset that crosses a border has to be translated, and translation is where mistakes happen. On that reading the conversion software cited as making metric unnecessary is itself evidence of a permanent overhead, and an overhead borne forever is worse than a transition borne once.

Rejecting the premises

[Rejecting P1] The same embedded stock existed wherever a changeover has been carried out, and it was replaced on ordinary renewal cycles rather than all at once, so the cost is spread rather than simultaneous. [Rejecting P2] Dual running is a property of the transition rather than of either system, so it argues for managing a changeover well, not for preferring the older measures. [Rejecting P3] If software has to convert figures continually, that is a standing cost of using a minority system rather than a reason the minority system is better. [Rejecting C] At most it follows that conversion has costs worth weighing, which is a claim about timing and not about which system is superior.