oh dear oh boy okay, I’ve tried to explain this to people and had them just get more annoyed, so I’ll give it a shot, but no promises that it will make any sense. Disclaimer also that I don’t really know what I’m talking about, I’ve just done a lot of baking, and ages ago I read something by Plato explaining why the musical scale is how it is, and I’m extrapolating from the two
(wow this turned out way longer than I meant it to because IT’S MIDNIGHT)
the metric system is a base 10 system, like most modern human math, so it is easy to use in the way people tend to do math these days - ie, by sitting down with either a piece of paper or a calculator and doing sums. It’s a good system for a lot of things, especially scientific applications where you need to be VERY precise and don’t want to waste time converting units, and need to do shit like calculus. It’s a highly rational way of doing it…if you are literate.
if you aren’t literate, or are less literate, it’s not a sensible way to construct a measuring system at all. If you measure something and come up with 367.45 cm, that’s nothing. You’re going to forget it, and you can’t easily divide it by anything, there’s no way to go from here
But consider the English Foot. We’ve all been working with a base 12 system without realizing it, and without really utilizing it for what it’s best for, which is easy mental division. This is where people get mad at me, they say math all gets terrible and ugly when you do it in feet, you end up trying to figure out how many sixteenths of an inch 0.135 is, or you end up with repeating decimals, and it all sucks super bad. To this I say yes, it does, because you’re thinking like a modern algebra student, and not like a medieval bricklayer.
The base 12 system of the traditional English foot is fantastic for mental math, because 12 is a highly divisible number. It’s easily divisible into halves, thirds, quarters, and sixths by most people in their heads. The inch is then typically divided into 1/16ths, which *super* suck to deal with on a calculator, but are really quite friendly if you just keep them as fractions like God and the Magna Carta intended. This is the kind of math most artisans need to do. You want supports placed evenly along a wall, to divide a piece of fabric in half, or to double a recipe. Nobody 1.7x’s a recipe. Metric would be great for that, but why would you do that? It wouldn’t be worth the math involved.
And listen, I also use a lot of metric baking recipes. Everything is in grams, you can measure everything the same way, and it’s super accurate. They’re great if you have a digital scale, but before the age of digital scales? Unfathomable. You (a medieval peasant) have a cup you’ve decided is The Cup, and sometimes you put in a half or a third or a quarter of that cup. THAT makes sense. Also, it’s a lot easier to double something that calls for 1 cup of flour than it is when it calls for 136 grams of flour, and this is for me, a person who learned math in the typical modern way and always has a calculator in their pocket. I would have the sourdough recipe I make every week memorized if it wasn’t in fucking grams. I DO have my pie crust recipe memorized. For every cup of flour you put in a third of a cup shortening, one tablespoon of butter, and start with 3 tablespoons of water (and a dash of salt). A double crust pie takes about 3 cups of flour, so that’s one cup shortening. Easy! A third of a cup of shortening in grams is 68.3333333. That’s nothing! That’s garbage!
“Wouldn’t it be more accurate to measure 68.3333333 grams, though?” Sure, but the amount of wet indigence you need to put in any baked thing changes with the fucking weather! That’s why this recipe says “start with 3 tbs water.” There’s no need to be more accurate, and in fact it would make things more difficult.
Okay that turned into a tangent about how to make pie crust, a thing I think everyone should learn because pie crust is delicious, but i hope you get the idea. TLDR sometimes you just want to divide things in thirds and have it not suck ass. The eldritch sigil of measurement conversions is a little less threatening if you realize every step up or down is a factor of thirds or fourths
fuck oh no another half remembered piece of pop science coming at you - the largest number a typical human can hold in their head *without language* is 3. You don’t need numbers to count to three, you don’t need to count to be aware of three, you can just see three things and say “that’s three.” Don’t believe me? That’s the whole basis of Roman numerals. The numbers 1-3 are representational, after that they get more symbolic, and you never end up with more than three of the same symbol in a row. After III comes IV, not IIII, and it’s just that III is much easier on the brain. For the same reason, a lot of English conversions are in factors of 4. There are 4 cups in a quart, and 4 quarts in a gallon, so you’re only dealing with measurements that are easy to hold in your head without counting. You never have to count out 4 cups if you convert. You either need 3 cups or 1 quart. Does that make sense? Anyone who has done Big Cooking should know that if you have to count cups beyond 3 or 4 it becomes very easy to lose track.
Now i’m not saying it’s all logical. It would be great if every step was a factor of 4, but they had to get fancy and throw pints in there. Pints aren’t too bad, that’s a factor of two, but I’ll be the first to admit that it makes no sense for one tablespoon to equal three teaspoons instead of four. But because this is a system that evolved over time instead of being constructed intentionally, you have to cut it some slack. I’m sorry to anyone who decided to read this, I should be in bed, but I actually care a lot about this and I swear it’s not just stockholm syndrome from Being American
This is the best explanation of this system that I’ve ever seen and I’m so grateful to have found it, because now I can shove it into the face of every person who whines at me about preferring Imperial measurements for cooking.
