It’s best to create notes which are only about one thing—but which, as much as possible, capture the entirety of that thing.
This way, it’s easier to form connections across topics and contexts. If your notes are too broad, you might not notice when you encounter some new idea about one of the notions contained within, and links to that note will be muddied. If your notes are too fragmented, you’ll also fragment your link network, which may make it harder to see certain connections. Evergreen notes should be densely linked
There’s no clear litmus test or correct answer here—just a bunch of tradeoffs.
The notion is quite similar to the software engineering principle of separation of concerns, which suggests that modules should only be “about” one thing, so that they’re more easily reusable. But likewise, if you fragment modules too much, you’ll have a cohesion problem. In this way, Evergreen note titles are like APIs.
The underlying principle I’d call the principle of atomicity: put things which belong together in a Zettel, but try to separate concerns from one another. For example, I might collect a list of assumptions in one Zettel which serves as an overview. like hard determinism . A related argument and its conclusion will be kept in another Zettel. Moral responsibility under hard determinism is a good example. I can re-use the arguments without buying into the assumptions because the arguments are of sufficiently general form. Atomicity fosters re-use which in turn multiplies the amount of connections in the network of Zettels.