For most of my life, I've had persons of various levels of authority tout the virtues of the supposedly scientific metric system, as well as deride the U.S. (of which I hold citizenship) as backwards for continuing to employ the imperial system. By this I mean there was a coordinated campaign carried out by my early educators which seems to have been adopted (although not the metric system itself) by my peers in adulthood.

As I have learned and studied, I have come to regard most of the supposed advantages as spurious, misguided, or just plain incorrect. While I will not go so far as to say the imperial system is universally superior, I will argue for relative advantages and disadvantages.

Possibly the most frequently touted advantage of the metric system is the ease of conversion between units, as they are base 10 multiples of each other. It is comparatively simple to convert millimeters to kilometers (1/10^6) than inches to miles (1/63360). The flaw of this argument is that it assumes there is a utility between converting inches and miles, or between millimeters and kilometers. For practical work, you select the most appropriate unit and stick with it, rounding to about 3 digits of precision. Outside of certain scientific pursuits, the base 10 conversion is simply not needed.

You can in fact test this yourself. In any area where metric is the norm, describe your height in decimeters, or how far you travel in hectometers. I'll bet you a shiny nickel you'll get the same confused look as if you tried to use cubits.

The further flaw is in assuming that base 10 is naturally the best or even a relatively good positional. The human mind is great at conceptualizing halves and thirds, and to a lesser extent 4ths, but not so great at 5ths or 10ths. The only factors of 10 are 5, and 2, which means realistically that we can only really conceptualize halving it. A dozenal (base 12) system would be an excellent alternative as 12s are evenly divisible by 2,3,4, and 6, which gives the foot a clear advantage over other metrics.

For woodworking, we typically work in either inches or millimeters. The inch folks when in need of smaller units, naturally switch to a sort of binary fractional system, where we subdivide the inch by halves (1/2, 1/4, 1/8, 1/16, etc.) As I mentioned before, we're really good at halving things, so subdividing the inch in this manner is super easy.

Metric measurements are supposedly based upon universal and consistent phenomena (such as the circumference of the earth) rather than the arbitrary and inconsistent (such as the distance between my nose and the tip of my finger). The base measurement, the meter, was supposedly 1/40,000,000th of the circumference of the globe. Now wait a minute... 1/4x10^7th doesn't look like an even division by decimal, how could this possibly be metric? Well dear reader, it's they decided on 1/10^7 of a **quadrant** of the earth. And believe it or not, 18th century French revolutionaries didn't have the most accurate ways to measure the circumference of the earth, so it was really just an estimate. In fact the length of a meter has been redefined multiple times since its inception so that it is now currently defined as 1/299792458th of a light second. I have trouble accepting that these assertions are any less arbitrary or any more scientific than the approximate length of an adult foot. And of course as metric system volume and mass are essentially tied to the meter, they are likewise just as arbitrary.

The most significant advantage of the imperial system is that the original bases for many of the measurements are relatable and practical. You carry around (baring disability) an approximate inch, foot, and yard everywhere you go. Miles being ~1000 paces are a little unwieldy, but still usable by the layman (to be fair, so was my 52 paces per 100 meters that I used in my grunt days).

Temperature is one place where metric got it right. The freezing and boiling points of water (in common use) are quite relatable, especially when compared to some that of some solution of water, ice, and ammonium chloride. Fahrenheit is still quite usable when you understand that water freezes at 32 degrees, and 100 degrees is a hot day. Either system is perfectly reasonable for day to day use (unlike Kelvin, which oughtn't be be used but by chemists)

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