The Zettelkasten: Topic Maps, Back to the Future

Abstract

The Zettelkasten ("card case"), introduced by the German social scientist Niklas Luhmann in 1981, is an external memory system composed of notes linked through explicit cross-references. A mesh of cross-references allows larger conceptual structures to emerge as the collection grows. Luhmann regarded his system as an indispensable combination of outboard memory and research assistant. Luhmann was known for his exceptional productivity and attributed much of it to his Zettelkasten. Others have tried to emulate his system with varying degrees of success. Luhmann's Zettelkasten was entirely paper-based; later times have seen efforts to computerize the design. Few seem to have achieved or even understood the levels of engagement that Luhmann wrote about: how his card collection supported fluid thinking, creativity, and serendipity. This paper presents a framework for understanding how such a system can achieve Luhmann-level support, why and how so many users fall short of these ideals. It pulls together aspects of information theory, cognitive and psychological science, human interface, movie production practice, Topic Maps data modeling, and library science to illuminate key concepts underlying highly effective thinking support. The work reported here is the outgrowth of four main threads dating back to the early 2000s. First was a series of browser bookmarks managers that were in essence lightweight zettelkastens that worked with bookmarks instead of notes [ Passin 2003 ]. Second was a program to allow writing XML source text, including RDF, in a highly simplified and intuitive way that relies on a few simple conventions [ Passin 2007 ]. Third was the development of a Topic Maps engine and various applications built on it. The fourth was extensive experience with systems modeling and enterprise architecture. Together these threads lead to an understanding that modeling systems need to be highly adaptable to changes and reorganization, that more semantics is captured by the structure than by individual information items, and that a flexible and adaptive system needs to present the user with extreme simplicity and intuitive operation as far as possible. This paper proposes that successful Zettelkasten implementations must provide very low cognitive friction so users do not feel impeded by their system. They should provide an outline-style view, and a user should be able to restructure the outline at any time in a convenient manner. Metadata is included by extremely simple markup that relies on a few conventions. Finally, though the underlying model is a Topic Map, most of the Topic Map machinery and details should be left implicit. This is essential to keep the cognitive friction low. Even though the framework presented in this paper seems complex, implementations can be surprisingly simple. This is demonstrated by the author's third-generation Zettelkasten implementation.