Argument maps are in line with what I'm looking for, but are not general enough (this by design, as their objective is specifically to create a visual representation for arguments). Unable to find a ready-made language, at different times I have played with the idea of creating my own, of which you can see a simple attempt on the left.
In addition to the lack of an existing language, an even more significant problem with a visual language is its reliance on a diagramming tool: so far, the choice of which tool to use isn't clear, existing tools are harder to use on mobile, and most actions must be made with a mouse or other pointing device instead of the keyboard, which makes them slow to use. This might also be the reason why we've yet to see a visual programming language attain an even modest level of success. This leads me to think that text, with its sentences organized in paragraphs, occasional bullet lists, and if long enough some headings, is still, regrettably, our best option for modeling thought.
