Photo: Wisepreneurs Podcast guest page
The German educator and researcher who carried Niklas Luhmann’s Zettelkasten into the English-speaking world and made the slip-box the intellectual backbone of modern personal knowledge management.
Field / lens: Zettelkasten, smart notes, writing-as-thinking
Based in: Hamburg, Germany
Timezone: CET (UTC+1/+2)
Why they matter to the Guild
Ahrens gave the field its founding text. How to Take Smart Notes arrived just as Roam, Obsidian, and Notion were making networked notes technically possible, and it supplied the intellectual framework those tools were missing. He reframed note-taking as the medium of thinking rather than the storage of it — a stance that sits at the root of how the Guild talks about working with notes.
The arc of their work
- Before — An academic career in the philosophy of education across several German universities (Bundeswehr Munich, Hamburg, Duisburg-Essen), producing the award-winning scholarly work Experiment and Exploration: Forms of World Disclosure (Springer).
- The landmark — How to Take Smart Notes (self-published 2017), which translated Luhmann’s slip-box into a practical, English-language method and catalysed the modern PKM movement.
- After — Now an independent researcher and coach. He released a revised, expanded second edition in 2022, built a course on running the method in Obsidian, and turned his research toward what makes people change their minds.
Key ideas and terms
- Zettelkasten (slip-box) — Luhmann’s networked note system; Ahrens’s central subject. See Glossary — Shared Language.
- Writing as thinking — Writing is not the output of thought but the medium through which thinking happens.
- Atomic notes — One idea per note, written in your own words, complete enough to stand alone.
- Bottom-up topic development — Topics emerge from clusters of connected notes rather than being chosen up front.
- Structure over willpower — A good system sustains intellectual work where motivation cannot.
Their works
Books
Courses
- How to Take Smart Notes in Obsidian — his own course applying the method in Obsidian (see Find them).
Find them
- Site: https://www.soenkeahrens.de / https://soenkeahrens.com
- Course: https://smartnotes.teachable.com
- X / Twitter: Sönke Ahrens (@soenke_ahrens) / X
- LinkedIn: https://www.linkedin.com/in/soenkeahrens/
Related leaders
- Niklas Luhmann — Ahrens’s intellectual source; the Zettelkasten he describes is Luhmann’s.
- Tiago Forte — A complementary external-thinking system (Second Brain / PARA) with a different organizing logic; both externalize, but Forte optimizes for output and Ahrens for insight.
- Nick Milo — Built the Linking Your Thinking community around many principles Ahrens articulated.
- David Allen — Both emphasize capturing and externalizing, though Allen’s focus is action and Ahrens’s is thought.