The spread of metrication around the world in the last two centuries has been met with both support and opposition. All countries except Burma (Myanmar), Liberia, the United States of America and partially the United Kingdom have officially adopted the metric system,[1] although actual usage may be more complex.
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One argument used by opponents of the metric system is that traditional systems of measurement were developed organically from actual use.[2] Early measures were human in scale. Traditional English expressions such as a stone's throw, within earshot, a cartload or a handful illustrate the thinking behind traditional measurements. These measures were often relational and commensurable: a request for a judgment of measure allowed for a variety of answers, depending on the context of the request. In parts of Malaysia, villagers asked the distance to the next village were likely to respond with three rice cookings; an approximation of the time it would take to travel there on foot. Everyone is assumed to know how long it takes to cook rice. Named units referring to seeming standards also were contextualized. The aune, a French ell used for measuring cloth, depended on the sort of cloth being measured, taking price and scarcity into account; an aune of silk was shorter than an aune of linen.[3]
Traditional English units of measure reflect these ways of measuring, including their lack of standardisation. These units were not scientifically precise, but were easy to learn and use for making rough estimates of size.
The British Weights and Measures Society has argued that metrics led to a greater complexity for consumers because, unlike the ounce, the gram is too small for measurement in everyday life.[4] and that the introduction of the metric system can aid profiteering if manufacturers downsize packages.[5]
Commentator Ken Alder noted that on the eve of the French Revolution a quarter of a million different units of measure were in use in France; in many cases quantity associated with each unit of measure differed from town to town and even from trade to trade.[6] He claimed that the metric system originated in the ideology of Pure Reason from the more radical element of the French Revolution, that it was devised in France to try to make France "revenue-rich, militarily potent, and easily administered", and that it was part of a conscious plan to transform French culture, meant to unify and transform French society: "As mathematics was the language of science, so would the metric system be the language of commerce and industry."[7] In his 1998 monograph Seeing Like a State: How Certain Schemes to Improve the Human Condition Have Failed, James C. Scott argued that central governments attempt to impose what he calls "legibility" on their subjects. Local folkways concerning measurements, like local customs concerning patronymics, tend to come under severe pressure from bureaucracies. Scott's thesis is that in order for schemes to improve the human condition to succeed, they must take into account local conditions, and that the high-modernist ideologies of the 20th century have prevented this. Scott cites the enforcement of the metric system as a specific example of this sort of failed and resented "improvement" imposed by centralizing and standardizing authority.[8] While the metric system was introduced in the French law by the revolutionary government in April 1795[9], it did not immediately displace traditional measurements in the popular mind. In fact, its use was initially associated with officialdom and elitism as Chateaubriand remarked in 1828: "Whenever you meet a fellow who, instead of talking arpents, toises, and pieds, refers to hectares, metres, and centimetres, rest assured, the man is a prefect."[10] However, it was largely used in France and in other countries by July 1837 when the decimal metric system was finally decided upon and considered the only official measurement system to be used in France
The British Weights and Measures Association argues that adopting metric measures in shops, especially in supermarkets, gives an opportunity for traders to increase prices covertly. They give numerous examples of packaged groceries to back up this contention.[11]
However, common metric units are larger than their nearest US/imperial counterparts: half a kilogram is more than a pound (0.5 kg = 1.102 lb), one metre is more than a yard (1 m = 1.094 yd), one litre is a little more than a US quart (1 L = 1.0567 qt) (though a little less than an imperial quart). When Pepsi became the first in the United States to sell soft drinks in two-litre bottles [12] instead of two-quart (US)(1.89 L) bottles, it was a success, and two-litre bottles are now well-established in the American soda market,[13] though fluid ounces remain the usual unit of measure for cans.
The move to smaller units (e.g. [milliliter] vs [fluid ounce], [gram] vs [ounce]) allows manufacturers to move sizes of packaging up and down with more precision. For example, a 2 oz packet of chips may be moved to 50 grams, then 45 grams. Likewise, strange packaging sizes may arise, such as 690 grams (about 24 oz) or 1200 grams (about 42 oz), usually resulting from conversion and rounding of obsolete units.
Metric opponents cite easier division of customary units as one reason not to adopt a decimalized system. For example, the customary units with ratios of 12 and 16 have more proper factors than the metric 10 - {2, 3, 4, 6} and {2, 4, 8} vs. {2, 5}.
Metric supporters point out that this argument is flawed in several ways. Firstly, only a few parts of the imperial or US customary systems actually feature the factor twelve, namely the inch-to-foot ratio and the obsolete troy ounce-to-troy pound ratio. Powers of two are more common, especially in volume measures, along with other factors including (rarely) five, seven and eleven. Metric supporters also point out the difficulty to convert with such ratios as five, seven and eleven are prime numbers.
Secondly, the argument compares the ratio between units for customary numbers, with the base of the numbering system for metric units. Both customary units and metric units use the same base 10 numbering system. However, the ratio between metric units, due to the use of an SI prefix, are all powers of 10. 1000 has many more proper factors than 12 or 16, with the set being {2, 4, 5, 8, 10, 20, 25, 40, 50, 100, 125, 200, 250, 500}.
The main disadvantage cited by critics of customary measures is the proliferation of units and difficulty in remembering the ratios between them.
Metric opposed artisans and practitioners may be concerned by certain dimensions being less memorable with metric units. As the table below shows, industries have adapted to such concern by rounding dimensions in metric units:
| Industry | Common reference | Metric reference |
|---|---|---|
| Carpentry | 4'×8' plywood | 1219 × 2438 mm (exact) 1200 × 2400 mm (new Europe) |
| "2 by 4" | 50.8 × 101.6 mm (exact) 50 × 100 mm (Europe) (but planing makes all beams 3~8 mm narrower) |
For some, anti-metrication is a form of traditionalism, looking to a history of usage that stretches back centuries or even millennia.
The non-metric units have different values in different times and places. At the time of the French revolution there were over 5000 different foot measures. The present UK imperial system is based on the Weights and Measures Act 1824, about 30 years after the founding of the metric system.
By contrast, the metric system has remained unchanged since it was first defined. Even though the metre was intended to equal one ten-millionth of the length of the meridian through Paris from pole to the equator, the calculated value was subsequently found to be short by 0.2 millimetres (because researchers miscalculated the flattening of the Earth). Nevertheless, the original reference metre was retained, leaving the exact distance from equator to pole slightly more than ten million metres. Subsequent advances in science and engineering have required increased precision in the definition, so that it is now defined as the length travelled by light in a vacuum during the time interval of 1⁄299,792,458 of a second. In addition, a reference standard (a rod of platinum-iridium alloy) is maintained by the inter-governmental organisation the International Bureau of Weights and Measures, and calibration of a standard metre is usually achieved (to one part in a billion, or slightly better in some recent installations[14]) by counting 1,579,800.298728 wavelengths of the ultra-fine (3s2 to 2p4) emission line of helium-neon laser light (this wavelength being approximately 632.99139822 nm in a vacuum). These refinements improved the precision and consistency with which the metre was defined.
The adoption of metric units has required some government compulsion[15] and some have argued that such policies are wrong in principle.[16] However, compulsory standards of weights and measures go back as far as Magna Carta. In 1824 in Britain, the Weights and Measures Act ("An Act for ascertaining and establishing Uniformity of Weights and Measures") consolidated the various gallons in use at the time and established a new imperial gallon, and prohibited the use of the older units, including what the United States now calls customary US measure.
Anti-metrication in the UK often manifests itself in conjunction with Euroscepticism because of the belief that the European Union is responsible for compulsory metrication. However, a Board of Trade committee had (without success) recommended metrication to the Government in 1951,[17] ten years before the UK first applied to join the EEC. The Board of Trade initiated metrication in 1965, with a target completion date of 1975[17] and the Metrication Board was established in 1968,[17] five years before the UK actually joined the European Economic Community (on its second attempt). The EU's own Units of Measurement Directive dated from 1971 and was substantially revised in 1979.
All Statutory Instruments for metrication since 1985 have relied on powers derived from the UK European Communities Act 1972. This helped to reinforce anti-EU sentiment as the British Parliament does not vote on such measures. More recently, anti-metrication supporters have asserted that the (claimed) legal compulsion to adopt the metric system instead of their traditional weights and measures is an infringement of a right to freedom of speech, though this claim has been consistently rejected by the courts. On 25 February 2004, the European Court of Human Rights rejected an application from some British shopkeepers who said that their human rights had been violated.
On 8 May 2007, several British newspapers including The Times[18] used correspondence between Giles Chichester MEP and EU Commissioner Günter Verheugen to report that the European Commission had decided to allow meat, fish, fruit and vegetables to continue to be sold in pounds and ounces. These reports did not mention that pounds and ounces would only retain supplementary-unit status. On 10 September, the EU Commission published proposed amendments to the Units of Measurement Directive that would permit supplementary units (such as pounds and ounces) to be used indefinitely alongside, but not instead of, the units catalogued in the Units of Measurement Directive.
In the US, there is also government compulsion with weights and measures. Federal and state laws control the labeling of goods for sale in the supermarket, drugs, wine, liquor, etc. The US Fair Packaging and Labeling Act mandates that measurement must be in both metric and U.S. customary units.[19] However, wine must be bottled in 50 mL, 100 mL, 187 mL, 375 mL, 500 mL, 750 mL, 1 L, 1.5 L, or 3 L sizes. Containers over 3 L must be bottled in quantities of even litres. No other sizes may be bottled.[20] Spirits must also be sold in metric quantities.[21] However, the US Code of Federal Regulations mandates that the net contents of beer labels must be stated in English units of measure.[22]
On March 29, 2010, NASA, the United States' space agency, decided to avoid making its new Constellation rocket system metric-compliant, especially due to pressure from manufacturers. It predicted that it would cost US$368 million to convert to metric measurements for parts made by both NASA and external companies. Constellation would have borrowed technology from the 1970s-era Space Shuttle program (which used non-metric measurements in software and hardware).[23] However, commercial space manufacturers, such as Space X, design their systems (e.g. Dragon and Falcon 9) using metric units.
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