IMHO he is also the best example for why this method doesn't work that well. His books lack focus. They are collection of thoughts with no mention of the sources. I say this as a trained sociologist who once was a proponent of his ideas.

Can you expand on that? Everyone talks about Zettelkasten but not the products of Zettelkasten. It'd be nice to know more about your opinion on Luhmann's work.

This is anecdotal, but I recall reading somewhere (maybe in a foreword) that e.g. Luhmann's "Social Systems" (1984; English translation 1985) was composed this way in purpose. The reader was supposed to be able to start the book from any chapter without feeling that he/she is missing something.

But, once more, this is anecdotal recall.

A similarly structured contemporary book is David Fleming's "Lean Logic: Dictionary for the Future and How to Survive It" [1]. A true masterpiece of composition IMO, and a work that took the author 30 years.

Interestingly, this work ethic also links to Luhmann's views on the time span of research relevant to him. Quoting a paper I found on the matter [2]:

" In 1962 he received a scholarship to Harvard and spent a year with Talcott Parsons. In 1968, he was appointed professor of sociology at the newly established University of Bielefeld, where he worked until his retirement. Shortly before his appointment he was asked on what subject he wished to work at university. His reply was: “The theory of modern society. Duration 30 years; no costs.” He consequently realised exactly this theoretical program. At the time of his death in December 1998, at the age of 70, he had published an oeuvre of over 14,000 printed pages."

[1]: https://www.amazon.com/Lean-Logic-Dictionary-Future-Survive/...

[2]: https://www.academia.edu/17063506/The_Legacy_of_Niklas_Luhma... Reference: Bechmann, G., and N. Stehr. "The Legacy of Niklas Luhmann. Society, January/February 2002.

The problem is that for many years his work was way to overrated in German speaking countries. His work also promoted the decline of sociology into irrelevance. One could argue though that his popularity was rather a symptom than the cause for this.

This. ZK works very well, but not in all areas. People in the humanities are more likely to benefit from it than, say, software engineers. I tried making software-related notes in a ZK and it just didn't _feel_ right. Maybe I should give it another go.