Why your Zettelkasten needs spaced repetition and collaboration
The Zettelkasten has recently gained popularity as a method of managing knowledge in your life, and building a second brain.
For those unfamiliar with the concept, a Zettelkasten leverages links to organize your notes as a connected web of knowledge, rather than a static collection (if you are familiar, feel free to skip ahead some paragraphs). It is a tool for writing, thinking and studying. Another way to look at it is as a mindmap where the nodes are notes, rather than single words.
As the name suggests, however, the Zettelkasten is not a recent Silicon Valley invention, but was developed over 50 years ago by the German social scientist Niklas Luhmann.
Niklas Luhmann published 50 books and 600 articles over the course of his life. His productivity, according to himself, came from the way he organized his note-taking.
He had a Zettelkasten (German for slipbox) full of small paper slips with notes. Like a webpage today, each note had a unique address. That way, note A could be “linked” to note B by writing down note B’s address. Like you can keep following links on Wikipedia, Luhmann could keep traveling through his Zettelkasten and never ran out of ideas.
How did he decide where to start his journeys? Not all notes are created equal: some notes where higher level, more general, than others. The starting points for his journeys where the notes at the top of the hierarchy.
Zettelkasten in the age of internet
With the internet and hypertext, linking has become much easier. We just need to make sure every note has a unique URL, so that we can use a hyperlink on another note to link to it.
The second ingredient for a digital Zettelkasten is a flexible form of hierarchy. This is achieved by creating index notes with links to many lower level notes. The hierarchy is actually a flexible heterarchy: a note can have multiple parents.
Since digital Zettelkasten require a much lower investment to create than Luhmann’s physical Zettelkasten, his productivity is now in reach of far more people. The reason we haven’t seen more of it yet is that apps making the process easy are starting to appear just now.
The biggest value the internet can bring to Zettelkasten is sharing and collaboration: we can have a public knowledge graph to which anyone can contribute.
But wait, you say, isn’t Wikipedia already a public knowledge graph?
To be sure, Wikipedia’s contribution to spreading and democratizing knowledge is not to be underestimated. However, there are two reasons why Wikipedia is not a collaborative Zettelkasten.
First, notes should be atomic: each notes contains exactly one, unique thought. A Wikipedia article however may contain many thoughts, or a single thought may be spread over many Wikipedia articles.
Second, Wikipedia presents a consensus based approach to knowledge. While anyone can edit, only one version of the truth ends up online at a single point in time. While consensus is helpful for education, it’s detrimental for knowledge-driven innovation. Innovators leverage existing ideas in a way that disagrees with the consensus.
It’s this kind of innovation that is enabled by a collaborative Zettelkasten. While the consensus might be that concept A is linked with concept B, an innovator might come along and link it to Z instead. As with most innovations, this will turn out to be wrong most of the time, but every once in a while it will create huge new value.
In summary, a collaborative Zettelkasten contains eternal knowledge like Wikipedia but has the social dynamics of Twitter.
A communication tool
This aligns nicely with what Luhmann intended: he saw his Zettelkasten primarily as a communication tool. Though on the receiving end wouldn’t be another person, but his future self. His future self could build new ideas on top of everything he wrote before. This is a strong example of intellectual future self-continuity.
Future self-continuity is the awareness that your future self is the same person you are now. It implies that you should treat your future self well. Often, this means delayed gratification: the amazing body in the future rather than the ice cream now.
Luhmann’s Zettelkasten does this for the intellectual self: you spend a bit of time now to write down a thought which is currently of no practical use, but it means your future self never has to start writing from a blank page. Many great books started from byproducts of previous projects, which, had they been discarded instead, would have been considered waste.
Furthermore, knowledge, like money, compounds over time: if you already know a lot of things, you will get more value out of learning yet another thing, as you have more things to relate it to.
A collaborative Zettelkasten also requires the awareness that making your environment better makes you better. Share knowledge with the people around you, rather than keeping it to yourself, and it will pay off later. In a collaborative Zettelkasten we can build not only on top of our own ideas, but also on other people’s ideas.
Writing = Thinking
It’s important to write your notes in your own words. The thought you’re trying to capture might not be yours, but from an article or book you read. You can make it yours by writing it in your own words.
Writing forces you to think about the concept. The first versions of your writings will seem clunky and confusing. Only as you think more and more about the concept will you be able to capture it in a way which is as simple as possible, but no simpler.
Writing for understanding is a variation of what’s named the Feynman technique after brilliant physicist Richard Feynman, who stated that you haven’t really understood something until you can explain it to a child. The Feynman technique applies even stronger in a collaborative Zettelkasten. Your notes now have an audience, and, on average, this audience will know less about the concept you’re writing about then you do, so you have to make it simple.
First vs second brain
Writing down your thoughts means transferring them from your first (physical) brain to your second (digital) brain. It reduces the mental load on your first brain, as you don’t have to keep it in short-term memory anymore.
But if that was all there is to it you might as well burn your notes. To let your notes work for you, you need to transfer them back into your first brain. After all, while your second brain is great at storing information, it’s your first brain that does the thinking, processing, and connecting, turning information into knowledge.
The trick is getting your notes into your long-term memory. While our short-term memory is limited to around 7 items at a time, long-term memory is virtually unlimited.
Enter spaced repetition: primarily known as a technique for effective studying, it actually makes any interaction with knowledge better. Spaced repetition means reviewing a unit of knowledge just at the moment you were about to forget it. This resets the forgetting curve and puts it more firmly in your long-term memory, which means you can increase the time interval before reviewing it again. Within a couple of reviews, the repetition interval will increase from daily to monthly to yearly, which makes it an extremely efficient way to memorize.
Since the knowledge is now always available to your brain, it will unconsciously be processed, and connected to other units of knowledge. This is what sparks creativity and innovation.
Spaced repetition is building a bridge between your first and your second brain. But there’s a gatekeeper on the bridge: we need to be selective which notes we want to remember forever.
How to implement spaced repetition in a Zettelkasten
So how do we build spaced repetition into our Zettelkasten? Start with a filtering process: identify the notes you want to remember. In my case, that’s usually either because I want to use a concept in everyday life, or because I want to deepen my understanding of it to form new connections.
Then I turn the selected notes into flashcards, by coming up with one or more specific questions which that note answers. The next day, I’ll review just the question, and try to actively recall in as much detail as possible what’s on that note. Then I read the rest of the Zettel to check how much I remembered. Depending on the quality of recall I’ll set the time for the next review closer or further in the future.
Tools like Traverse make this process easy with native spaced repetition, but it can also be done in Notion using toggles and custom formulas, or in Roam with deltas.
How to collaborate on Zettelkasten
Since a note in a Zettelkasten is atomic, it makes sense to view it as pertaining to a single person, representing that person’s thought. Other users however, can link to that thought on their own notes, building on it, contradicting it or viewing it from another angle. These linked notes will then show up as backlinks when viewing the original note, and the backlinks will become a place where all the discussion around a note can be found. This method can be used with any tool that supports backlinks and publishing or sharing of notes.
Conclusion
Building a Zettelkasten can increase our knowledge and productivity, but to get the most out of it we have to put our first brain first. The second brain is only there to make the first brain better.
In a collaborative Zettelkasten multiple brains can build on each other’s ideas. With the knowledge half-life of Wikipedia but the communication speed of Twitter they can become a powerful tool for driving innovation and intellectual progress.
This collaborative Zettelkasten is available on Traverse.
