Twice now this week someone referenced just-in-time vs just-in-case learning. I'm afraid I can't remember the first (probably a Bluesky post lost to the ether), but the second was the final episode of People I Mostly Admire.

In it, Steve Levitt expresses dismay at the just-in-case learning that public education imposes. How often do we hear people say "When will I need to use Calculus?" Good heavens, "The mitochondria is the powerhouse of the cell" has become a meme because of how useless it is to most people.

The other side is just-in-time learning. You have a new project that requires you to use unfamiliar tools? You learn it on the spot. You want to make a 3D video game? Congratulations, you now have to learn how matrices work. Instead of a curriculum mandate dictating your learning, you choose what is most useful to what you want to do.

I'm in favor of this, especially as an alternative to current US public school education, where "No Child Left Behind" means some children are bored waiting for everyone else to catch up.

But I also don't want to dismiss just-in-case learning either. I'm a huge fan of curiosity for curiosities' sake. I love learning about space, and time, and spacetime, particles and physics, biology and economics.

What's more, I love learning about web development, even if it's not related to things I'm working on. I've never built a Svelte app before, but stay informed about their developments, both in case I work on a Svelte app someday, but also because the ideas they're working on might someday connect to some other thing.

This is a fun 2x2. All knowledge fits into one of these squares, with the things you actually know in the top left, and the things you don't even know that you don't know are in the bottom right. In fact, almost all knowledge is in that square.

It illustrates how valuable just-in-case learning is for moving knowledge from "Unknown Unknowns" over to "Known Unknowns" — you might not know everything about the thing, but at very least you know that it is a thing so that someday you can JIT learn about it.

Sometimes its good to know things just because.