Use case: the metric system, or, all that useless beauty

Ah, nothing gets international rivalry boiling like soccer football and the metric system. One wonders why the metric system hasn’t taken off here in the US. I posit this: it doesn’t offer any advantage to end users, ie, regular citizens. Let’s do the use case.

Proponents of the metric system argue that it’s utterly logical. And it is; everything is decimal (base 10), so we can easily convert from grams to kilograms.

The question is, how often do we do that? To my international readers, do you ever find yourself saying, “Well, thanks for the distance in kilometers, but to get a sense of it, I prefer to think of it in decameters.”? I wager you don’t.

Similarly in the states, we think in miles. I’ve never known anyone to express a travelling distance in feet. So even though the conversion is tedious and arbitrary, it doesn’t present a practical barrier in our daily lives. Our mental models don’t require it.

There are engineers, like myself, who become convinced that our model is utterly elegant and consistent and logical. Then we observe what our users are actually trying to achieve, and discover that they don’t respond to all that useless beauty.

So it is with the metric system. Obviously, there is nothing wrong with it; it just doesn’t serve a use case at human scale.

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Side note: my background is in physics and yes, we do jump between orders of magnitude with regularity. And we use the metric system. The right tool for the right user.