“That island is reported to have received about 250 millimetres of rain from the event.”
250 millimeters? How much is that? Well, what is a millimeter? Hmm, about a fingernail thickness.
Let’s see 250 fingernail thicknesses…. Um, well 10 fingernail thicknesses, FTs for short, are a centimeter so we have 25 centimeters then. But what’s a centimeter? Um, about thickness of your pinky finger. OK, so we have 25 pinky finger thicknesses PTs for short. But let’s see 25 PTs… hmm, a PT is still not so helpful. But about 5 PTs are as think as a good hardback novel. So we have 5 novel thicknesses. OK, now we’re getting somewhere. 5 thick novels stacked are about 10 inches. An inch being about the length of a knuckle. 12 of them being about the length of your foot. Ooh that’s right! Feet!
“The recipe calls for 250 milliliters of milk.”
Hmm, well, a milliliter is a cubic centimeter of water, so that’s about half a teaspoon, and since I drink tea I figure that’s about 125 teaspoons, 125 good sips of tea, about a cup of tea.
You see, the metric system has no human basis for context. Millimeter? Milliliter? What are they? How can you quickly judge distance or volume with such numbers?
So the question is, do Europeans who use the metric system, intrinsically know what distance 250 millimeters is? What 250 milliliters are? To me they’re just abstract tiny increments that have no real world contextual basis and so must be converted into something that has *meaning* to humans.