Thinking further: I wonder if the (very) rough categorisation I put forward resonates with anyone else, or if anyone might offer alternative views? I know there are some pretty obvious and messy points of intersection, which makes me wonder whether this is more of a Venn diagram than a sliding scale…

I guess outliners would sit somewhere in the linear, hierarchical category, though Dynalist would skew towards the structured visual category, since it does offer a mind-map view. And Roam (and its many competitors and clones) would be just another flavour of structured visual thinking?

Muse (https://museapp.com/ feels like it deserves a mention in any conversation about thinking tools…

jsamlarose wrote:

This might be of use?
https://github.com/brettkromkamp/awesome-knowledge-management
Lots of thinking about knowledge management, but the apps/tools list
should offer a solid starting point.

As others have acknowledged, this sounds like quite the undertaking.
It'd be interesting to see even the beginnings of a taxonomy of thinking
tools. Three categories for thinking tools are (for my own purposes)
are:
- linear thinking (note-taking in an app like Drafts)
- structured visual thinking (hierarchical mind-mapping tools like
iThoughts, and non-hierarchical knowledge graphs like Kinopio)
- loose/freehand visual thinking (sketch/drawing apps like Concepts)

Even this isn't particularly cast-iron; plenty of tools sit on the
borders and cross the divides...