I’ve always read a lot, but never been satisfied with how I manage information that I consume. I’d read a book or article and take notes—sometimes very detailed notes—but recovering information from my notes was frustrating. My notes were spread across multiple notebooks. I would sometimes migrate my written notes to digital notes apps, but the work was tedious and therefore a difficult habit to maintain. I learned from what I read, but I felt that my process was full of holes.

I’ve tried in the past to devise new systems for personal knowledge management. But, it’s only been this year that I’ve stumbled across methodologies that have really really resonated with me. Specifically, these have been the zettelkasten or slip-box method, described in Sonke Ahrens’ book How to Take Smart Notes, and the PARA method taught by Tiago Forte.

Here, I want to summarize what I learned from Ahrens. I plan to return to Forte in a later post.

Niklas Luhmann and his zettelkasten

Ahrens’ book is based heavily on a research and note-taking method used by German sociologist Niklas Luhmann. Luhmann was a prolific scholar: he wrote more than 70 books and close to 400 articles over his career. Moreover, he wrote broadly, delving into subjects as diverse was ecology, economy, and love.

Luhmann attributed his prodigious output to his note-taking system, called the zettelkasten or slip-box method. While reading, Luhmann took brief notes about the text on one side of a notecard. (The other side would list bibliographic information.) Luhmann filed these in one catalogue. Later—but not too much later—he reviewed his notes and in a similar fashion took notes on his own thoughts and ideas about what he had read.

The way Luhmann took notes was not all that different from the way he wrote his manuscripts. He wrote them in careful, complete sentences and in his own words.  He understood that mastery of material required translation.

When creating his own notes he followed a principle of atomicity. That is, he wrote only one idea per card. This enabled him to more easily separate out different concepts and ideas. A text may contain many valuable concepts or ideas; keeping these ideas discrete allowed him to treat each a unique thought.

This atomic approach facilitated the most important element of his system: linking. Luhmann wrote new notes with his mind on how they connected to other notes already in his slip box. Rather that organizing his notes by subject or author, he numbered them relationally. Each note had a unique identifier he used as a pointer to connect it to other relevant notes. It served as a an analog hyperl ink. Luhmann also wrote index notes, listing all the notes he had on a specific topic by their identifiers.

For Luhmann, working with his slip-box was less information retrieval than a conversation. Luhmann didn’t need to rely on his recall to find his old ideas. The slip-box reminded him of what he had forgotten. His process surfaced connections that would not have been immediately obvious through typical methods of idea generation, research, or brainstorming. Finally, his slip-box kept him honest. It surfaced contradictory ideas, mitigating confirmation bias and helping him avoid the feature-positive effect—that is, prioritizing information that is more readily available.

Benefits of the slip-box method

The slip-box method appeals for several reasons.

Perhaps the most significant benefit of the slip-box method is that it moves the bottleneck of knowledge production. Many storage methods are organized around the needs of the archivist. Information is filed wherever will suit the needs of the system of organization. But, what matters more is the moment of retrieval. As Tiago Forte points out, one of the fundamental challenges of note-taking and knowledge management is that we read things at the wrong time. An idea is interesting when we come across it, but it might not yet be useful. We need to consider when will we need to encounter this information again. With the slip-box method, we can expend less energy recalling what information we have saved and where we have stored it. Instead, we can dedicate our mental bandwidth to where it is most valuable: generating new ideas.

This leads to greater benefits. One tenet of the slip-box method is that that new ideas come from old ideas. Ahrens emphasizes that there is no such thing as “starting from scratch.” Every intellectual endeavour requires that we engage with and process existing ideas. There’s a persistent myth that insight follows inspiration. But, creativity requires consumption. Nothing comes from nothing. True inspiration—real, transformative insight—arrives through the serendipitous collision between old ideas. It’s intellectual fusion.

The slip-box is powerful because it facilitates these collisions. It facilitates our stumbling across knowledge that we may have forgotten, or that we aren't yet aware is relevant. And, once a critical mass of knowledge is achieved, the slip-box yields compounding returns. The greater the volume and diversity of the information we put into the slip-box, the greater the value we get out of it.

Most importantly, the slip-box puts into conversation contradictory or competing ideas. It therefore helps mitigate the risk of cognitive bias. Because we don’t rely on recall to determine which notes to search for, we are less subject to the feature-positive effect. As well, the slip-box can help limit the risk of confirmation bias. Of course, this assumes that we haven’t created our own echo chamber by only adding notes that reinforce our existing position. That’s much easier said than done.

Finally, there’s power in the fact that the slip-box method’s demand that we articulate ides in our own words. Writing is reflection. By making writing coextensive with learning, the slip-box method forces us to shift from consumption to creation. I think this is where I struggled before. After all, consumption feels so good. It’s easy to mistake reading and collecting information for productivity. I’ve seen this described elsewhere as the collector’s fallacy. But to truly acquire information we must not simply collect it, but process and engage with it. Writing is not the result of thinking; writing is thinking.

Implications of Ahrens’ work

If you are someone who works with information, I can’t recommend Ahrens’ book enough. Almost immediately after I began taking notes this way, I felt like a creative block had lifted. Instead of simply capturing data, I was engaging with it. I started to think more clearly and develop my own perspectives on what I read. I was impressed with how easily I was able to make connections between disparate sources. This approach also made me more mindful of the sources of my own positions. I started to identify patterns in my reading that may have created blind spots. This, to me, is immeasurably valuable.

I was so taken by the method that I immediately began to think about its applications beyond personal knowledge management. For example, what would a slip-box-based information architecture look like? The slip-box’s emphasis on retrieval is consistent with the function of a user-centric information architecture. After all, the point of a good IA is not that the organization can store information in a way that makes sense to its designers, but that the end user is able to find what they need when they need it. Yet, many companies structure websites around org charts or product lines. It’s difficult to understand every context in which the user will seek information. Still, with research it’s possible to identify likely scenarios. This is, I think, a feature of “inside-out” methods like the core content model.

Speaking of research, the slip-box method provides a useful way to organize generative insights about users. One problem every user researcher has mulled over is making sure insights are available when and where they are needed. Key pieces of information—data that may be more valuable in hindsight than in the moment of collection—are often left mouldering in the back pages of PowerPoint decks or on sticky notes barely clinging to a whiteboard.

I can imagine a slip-box that comprises index notes organized around some subjects (jobs to be done, personas, journeys, features) but that relies on building a network of links that confront the researcher with insights that they may not be aware of or have forgotten. I think this is consistent with Tomer Sharon’s concept of the research nugget and suspect that there are platforms out there that facilitate this. Some user research platforms try to solve for this with elaborate tagging systems, which have a tendency to become cluttered and unmanageable. And, I'm not sure how well either of these systems foster serendipity as well as the slip-box does. It’s something I’d like to explore further. I’m curious to see how effectively this method scales beyond a single author.

Further reading

If you’re interested in learning more, there are a few resources I can recommend. Tiago Forte has written a summary of How to Take Smart Notes that goes into greater detail than mine. He outlines ten core principles of Ahrens’ book, as well as detailing a step-by-step process for taking start notes. Tiago has also interviewed Ahrens about the slip-box method.

There’s also a robust online community dedicated to the slip-box method at zettelkasten.de. Be forewarned: this site is a rabbit hole if, like me, you’re a nerd for topics like knowledge management. As well, much of the content assumes a base level of knowledge that can feel intimidating if you’re new to this subject. Make no mistake; the forums are very helpful. But, there are many ways of implementing the slip-box method and some folks have strong opinions about what’s right and what’s wrong. It’s all friendly debate, though.

Slip-box software

Luhmann relied on physical cards for his slip-box. Now, we have software. I initially got started using Bear, which is entirely adequate. It’s a well-designed, visually appealing program that’s easy to use, but requires the Apple ecosystem.

There’s also The Archive. It features a minimalist interface and assumes some knowledge of markdown. But, it’s also designed specifically to support a slip-box method.

I suspect Roam is probably the application that is best matched to the slip-box method. I’ve read it was inspired by Luhmann, and it’s an impressive program. I’ve watched a power user work in it, and it’s truly impressive how easy it makes building a network of linked artifacts. I’m reluctant to embrace it, though, as I’ve read that they will be introducing a pricing model in the future and I don’t yet know how much it will cost. With that said, I understand that it’s possible to export your content into a portable markdown format.

Today, I use Evernote. I wouldn’t suggest that Evernote is best suited to the slip-box system, but since taking the Building a Second Brain course I’ve embraced it because of how easy it makes information capture.

Parting notes

I think the best advice I can give to anyone considering the slip-box method is this: just get started. You can spend a lot of time churning over whether you are doing it right, or whether you have the perfect app set up. Don’t worry about it. Just write a note. Then another. Make links. Repeat the process. The only person it has to work for is you.