Brennen has a blog post, the zettelkasten / the zeitgeist, where he says: “Luhmann’s Zettelkasten was a kind of paper hypertext. He numbered individual cards/slips in such a way that related things could be found in physical proximity, and made links between cards by referencing those identifiers.”
In modern digital era, Zettelkasten can be implemented using any kind of hypertext system. A directory with interlinked hypertext documents, for example. Most people use a dedicated wiki software or something like Roam.
TimurIsmagilov thinks that the idea of Zettelkasten is too vague. Nowadays, everything is hypertext. Also, in MycorrhizaWiki there is always a link to parent hyphae, does it make every MycorrhizaWiki wiki a Zettelkasten? Do links to children hyphae/pages count as links? Do links to other resources count?
AlexSchroeder: It all depends on whether you think that the size limitation of the original index cards was a feature or not. All the wikis I know use more than just two sentences per page.
TimurIsmagilov: I think it was. So what?
Alex: in that case, wikis incentivize (“afford” in the usability sense) writing longer essays which does not produce the same result as the old school Zettelkasten, where more thought is invested in the summary, and sequences of thoughts lead to sequences of cards and branches get included everywhere without prejudice of one branch over the other, unlike a wiki, where the text that continues on the same page is preferred over the text that begins behind a link. Or something like that. I do not agree with this point of view but that’s how it was explained to me.
Here’s an essay arguing you should start with small paper cards and not use larger ones: The Zettelkasten Method: “It forces ideas to be broken up into simple pieces, which helps to clarify them. Breaking up ideas forces you to link them together explicitly, rather than relying on the linear structure of a notebook to link together chains of thought.”
Alex Schroeder: I agree, the small space provided by Tiddly Wiki (at least when I wrote some stuff for it) fits the bill.
In a Zettelkasten, the embodiment in index cards has two consequences: the cards are required to be sorted otherwise you can’t find things, and new cards must therefore be inserted between existing cards. If you have cards 11a5 and 11a6 and you want to insert a new thought after 11a5, you end up with a new sort order 11a5, 11a5a, 11a6, … – the question is whether this results in new ideas when rereading your notes compared to a wiki where 11a5 links to both 11a5a and 11a6, but 11a5a does not necessarily link to 11a6 as they are not actually cards in physical proximity.