In the early 1950s, Luhmann spent a year at the Lüneburg Higher Administrative Court organizing a reference system for the administrative court decisions to enable researchers to see what decisions had been made in the higher courts.

Though he had begun his zettelkasten during his studies, this referencing system may have influenced the structure of his own note taking system.

Can we pin the dates on these practices down more closely?

According to the Niklas Luhmann-Archiv, Luhmann began his first zettelkasten in 1952 likely when he was working as a legal trainee in Lüneburg or as a government councilor in the Ministry of Education in Lower Saxony.

This timeframe would have been just after Johannes Erich Heyde had published the 8th edition of Technik des wissenschaftlichen Arbeitens in 1951.

Link to: - https://hypothes.is/a/Jn9elsk5Ee2hsLP5WWBEBw on dates of NL ZK - https://hypothes.is/a/CqGhGvchEey6heekrEJ9WA aktenzeichen - https://hypothes.is/a/4wxHdDqeEe2OKGMHXDKezA Clemens Luhmann link

Thoughts on Zettelkasten numbering systems

I've seen variations of the beginner Zettelkasten question:

"What happens when you want to add a new note between notes 1/1 and 1/1a?"

asked at least a dozen times in the Reddit fora related to note taking and zettelkasten, on zettelkasten.de, or in other places across the web.

Dense Sets

From a mathematical perspective, these numbering or alpha-numeric systems are, by both intent and design, underpinned by the mathematical idea of dense sets. In the areas of topology and real analysis, one considers a set dense when one can choose a point as close as one likes to any other point. For both library cataloging systems and numbering schemes for ideas in Zettelkasten this means that you can always juxtapose one topic or idea in between any other two.

Part of the beauty of Melvil Dewey's original Dewey Decimal System is that regardless of how many new topics and subtopics one wants to add to their system, one can always fit another new topic between existing ones ad infinitum.

Going back to the motivating question above, the equivalent question mathematically is "what number is between 0.11 and 0.111?" (Here we've converted the artificial "number" "a" to a 1 and removed the punctuation, which doesn't create any issues and may help clarify the orderings a bit.) The answer is that there is an infinite number of numbers between these!

This is much more explicit by writing these numbers as:<br /> 0.110<br /> 0.111

Naturally 0.1101 is between them (along with an infinity of others), so one could start here as a means of inserting ideas this way if they liked. One either needs to count up sequentially (0, 1, 2, 3, ...) or add additional place values.

Decimal numbering systems in practice

The problem most people face is that they're not thinking of these numbers as decimals, but as natural numbers or integers (or broadly numbers without any decimal portions). Though of course in the realm of real numbers, numbers above 0 are dense as well, but require the use of their decimal portions to remain so.

The tough question is: what sorts of semantic meanings one might attach to their adding of additional place values or their alphabetical characters? This meaning can vary from person to person and system to system, so I won't delve into it here.

One may find it useful to logically chunk these numbers into groups of three as is often done using commas, periods, slashes, dashes, spaces, or other punctuation. This doesn't need to mean anything in particular, but may help to make one's numbers more easily readable as well as usable for filing new ideas. Sometimes these indicators can be confusing in discussion, so if ever in doubt, simply remove them and the general principles mentioned here should still hold.

Depending on one's note taking system, however, when putting cards into some semblance of a logical sort-able order (perhaps within a folder for example), the system may choke on additional characters beyond the standard period to designate a decimal number. For example: within Obsidian, if you have a "zettelkasten" folder with lots of numbered and named files within it, you'll want to give each number the maximum number of decimal places so that when doing an alphabetic sort within the folder, all of the numbered ideas are properly sorted. As an example if you give one file the name "0.510 Mathematics", another "0.514 Topology" and a third "0.5141 Dense Sets" they may not sort properly unless you give the first two decimal expansions to the ten-thousands place at a minimum. If you changed them to "0.5100 Mathematics" and "0.5140 Topology, then you're in good shape and the folder will alphabetically sort as you'd expect. Similarly some systems may or may not do well with including alphabetic characters mixed in with numbers.

If using chunked groups of three numbers, one might consider using the number 0.110.001 as the next level of idea between them and then continuing from there. This may help to spread some of the ideas out as surely one may have yet another idea to wedge in between 0.110.000 and 0.110.001?

One can naturally choose almost any any (decimal) number, so long as it it somewhat "near" the original behind which one places it. By going out further in the decimal expansion, one can always place any idea between two others and know that there will be a number that it can be given that will "work".

Generally within numbers as we use them for mathematics, 0.100000001 is technically "closer" by distance measurement to 0.1 than 0.11, (and by quite a bit!) but somehow when using numbers for zettelkasten purposes, we tend to want to not consider them as decimals, as the Dewey Decimal System does. We also have the tendency to want to keep our numbers as short as possible when writing, so it seems more "natural" to follow 0.11 with 0.111, as it seems like we're "counting up" rather than "counting down".

Another subtlety that one sees in numbering systems is the proper or improper use of the whole numbers in front of the decimal portions. For example, in Niklas Luhmann's system, he has a section of cards that start with 3.XXXX which are close to a section numbered 35.YYYY. This may seem a bit confusing, but he's doing a bit of mental gymnastics to artificially keep his numbers smaller. What he really means is 3000.XXX and 3500.YYY respectively, he's just truncating the extra zeros. Alternately in a fully "decimal system" one would write these as 0.3000.XXXX and 0.3500.YYYY, where we've added additional periods to the numbers to make them easier to read. Using our original example in an analog system, the user may have been using foreshortened indicators for their system and by writing 1/1a, they may have really meant something of the form 001.001/00a, but were making the number shorter in a logical manner (at least to them).

The close observer may have seen Scott Scheper adopt the slightly longer numbers in the thousands (like 3500.YYYY) as a means of remedying some of the numbering confusion many have when looking at Luhmann's system.

Those who build their systems on top of existing ones like the Dewey Decimal Classification, or the Universal Decimal Classification may wish to keep those broad categories with three to four decimal places at the start and then add their own idea number underneath those levels.

As an example, we can use the numbering for Finsler geometry from the Dewey Decimal Classification wikipedia page shown as:

``` 500 Natural sciences and mathematics

510 Mathematics

    516 Geometry

        516.3 Analytic geometries

            516.37 Metric differential geometries

                516.375 Finsler geometry

```

So in our zettelkasten, we might add our first card on the topic of Finsler geometry as "516.375.001 Definition of Finsler geometry" and continue from there with some interesting theorems and proofs on those topics.

Of course, while this is something one can do doesn't mean that one should do it. Going too far down the rabbit holes of "official" forms of classification this way can be a massive time wasting exercise as in most private systems, you're never going to be comparing your individual ideas with the private zettelkasten of others and in practice the sort of standardizing work for classification this way is utterly useless. Beyond this, most personal zettelkasten are unique and idiosyncratic to the user, so for example, my math section labeled 510 may have a lot more overlap with history, anthropology, and sociology hiding within it compared with others who may have all of their mathematics hiding amidst their social sciences section starting with the number 300. One of the benefits of Luhmann's numbering scheme, at least for him, is that it allowed his system to be much more interdisciplinary than using a more complicated Dewey Decimal oriented system which may have dictated moving some of his systems theory work out of his politics area where it may have made more sense to him in addition to being more productive on a personal level.

Of course if you're using the older sort of commonplacing zettelkasten system that was widely in use before Luhmann's variation, then perhaps using a Dewey-based system may be helpful to you?

A Touch of History

As both a mathematician working in the early days of real analysis and a librarian, some of these loose ideas may have occurred tangentially to Gottfried Wilhelm Leibniz (1646 - 1716), though I'm currently unaware of any specific instances within his work. One must note, however, that some of the earliest work within library card catalogs as we know and use them today stemmed from 1770s Austria where governmental conscription needs overlapped with card cataloging systems (Krajewski, 2011). It's here that the beginnings of these sorts of numbering systems begin to come into use well before Melvil Dewey's later work which became much more broadly adopted.

The German "file number" (aktenzeichen) is a unique identification of a file, commonly used in their court system and predecessors as well as file numbers in public administration since at least 1934. We know Niklas Luhmann studied law at the University of Freiburg from 1946 to 1949, when he obtained a law degree, before beginning a career in Lüneburg's public administration where he stayed in civil service until 1962. Given this fact, it's very likely that Luhmann had in-depth experience with these sorts of file numbers as location identifiers for files and documents. As a result it's reasonably likely that a simplified version of these were at least part of the inspiration for his own numbering system. † ‡

Your own practice

At the end of the day, the numbering system you choose needs to work for you within the system you're using (analog, digital, other). I would generally recommend against using someone else's numbering system unless it completely makes sense to you and you're able to quickly and simply add cards to your system with out the extra work and cognitive dissonance about what number you should give it. The more you simplify these small things, the easier and happier you'll be with your set up in the end.

References

Krajewski, Markus. Paper Machines: About Cards & Catalogs, 1548-1929. Translated by Peter Krapp. History and Foundations of Information Science. MIT Press, 2011. https://mitpress.mit.edu/books/paper-machines.

Munkres, James R. Topology. 2nd ed. 1975. Reprint, Prentice-Hall, Inc., 1999.

imposed system or on one’s own non-generalizable system, at least when it comes to the subdivisions.

Heyde makes the suggestion of using one's own classification system yet again and even advises against "having to rely on a stranger's imposed system". Does Luhmann see this advice and follow its general form, but adopting a numbering system ostensibly similar, but potentially more familiar to him from public administration?

In a break from the more traditional subject heading filing system of many commonplacing and zettelkasten methods, in addition to this sort of scheme Heyde also suggests potentially using the Dewey Decimal System for organizing one's knowledge.

While Luhmann doesn't use Dewey's system, he does follow the broader advice which allows creating a dense numbering system though he does use a different numbering scheme.

With respect to Niklas Luhmann's zettelkasten, it seems he eschewed the Heyde's advice to use subject headings as the Anschrift (address). Instead, much like a physical street address or card card catalog system, he substituted a card address instead. This freed him up from needing to copy cards multiple times to insert them in different places as well as needing to create multiple cards to properly index the ideas and their locations.

Without this subtle change Luhmann's 90,000 card collection could have easily been 4-5 times its size.

Heyde indicates how "valuable notes and chains of thought are" but also points out "how uncontrollable and irretrievable" they are.

This statement is strong evidence along with others in this chapter which may have inspired Niklas Luhmann to invent his iteration of the zettelkasten method of excerpting and making notes.

(link to: Clemens /Heyde and Luhmann timeline: https://hypothes.is/a/4wxHdDqeEe2OKGMHXDKezA)

Presumably he may have either heard or seen others talking about or using these general methods either during his undergraduate or law school experiences. Even with some scant experience, this line may have struck him significantly as an organization barrier of earlier methods.

Why have notes strewn about in a box or notebook as Heyde says? Why spend the time indexing everything and then needing to search for it later? Why not take the time to actively place new ideas into one's box as close as possibly to ideas they directly relate to?

But how do we manage this in a findable way? Since we can't index ideas based on tabs in a notebook or even notebook page numbers, we need to have some sort of handle on where ideas are in slips within our box. The development of European card catalog systems had started in the late 1700s, and further refinements of Melvil Dewey as well as standardization had come about by the early to mid 1900s. One could have used the Dewey Decimal System to index their notes using smaller decimals to infinitely intersperse cards on a growing basis.

But Niklas Luhmann had gone to law school and spent time in civil administration. He would have been aware of aktenzeichen file numbers used in German law/court settings and public administration. He seems to have used a simplified version of this sort of filing system as the base of his numbering system. And why not? He would have likely been intimately familiar with its use and application, so why not adopt it or a simplified version of it for his use? Because it's extensible in a a branching tree fashion, one can add an infinite number of cards or files into the midst of a preexisting collection. And isn't this just the function aktenzeichen file numbers served within the German court system? Incidentally these file numbers began use around 1932, but were likely heavily influenced by the Austrian conscription numbers and house numbers of the late 1770s which also influenced library card cataloging numbers, so the whole system comes right back around. (Ref Krajewski here).

(Cross reference/ see: https://hypothes.is/a/CqGhGvchEey6heekrEJ9WA

Other pieces he may have been attempting to get around include the excessive work of additional copying involved in this piece as well as a lot of the additional work of indexing.

One will note that Luhmann's index was much more sparse than without his methods. Often in books, a reader will find a reference or two in an index and then go right to the spot they need and read around it. Luhmann did exactly this in his sequence of cards. An index entry or two would send him to the general local and sifting through a handful of cards would place him in the correct vicinity. This results in a slight increase in time for some searches, but it pays off in massive savings of time of not needing to cross index everything onto cards as one goes, and it also dramatically increases the probability that one will serendipitously review over related cards and potentially generate new insights and links for new ideas going into one's slip box.

While Heyde outlines using keywords/subject headings and dates on the bottom of cards with multiple copies using carbon paper, we're left with the question of where Luhmann pulled his particular non-topical ordering as well as his numbering scheme.

While it's highly likely that Luhmann would have been familiar with the German practice of Aktenzeichen ("file numbers") and may have gotten some interesting ideas about organization from the closing sections of the "Die Kartei" section 1.2 of the book, which discusses library organization and the Dewey Decimal system, we're still left with the bigger question of organization.

It's obvious that Luhmann didn't follow the heavy use of subject headings nor the advice about multiple copies of cards in various portions of an alphabetical index.

While the Dewey Decimal System set up described is indicative of some of the numbering practices, it doesn't get us the entirety of his numbering system and practice.

One need only take a look at the Inhalt (table of contents) of Heyde's book! The outline portion of the contents displays a very traditional branching tree structure of ideas. Further, the outline is very specifically and similarly numbered to that of Luhmann's zettelkasten. This structure and numbering system is highly suggestive of branching ideas where each branch builds on the ideas immediately above it or on the ideas at the next section above that level.

Just as one can add an infinite number of books into the Dewey Decimal system in a way that similar ideas are relatively close together to provide serendipity for both search and idea development, one can continue adding ideas to this branching structure so they're near their colleagues.

Thus it's highly possible that the confluence of descriptions with the book and the outline of the table of contents itself suggested a better method of note keeping to Luhmann. Doing this solves the issue of needing to create multiple copies of note cards as well as trying to find cards in various places throughout the overall collection, not to mention slimming down the collection immensely. Searching for and finding a place to put new cards ensures not only that one places one's ideas into a growing logical structure, but it also ensures that one doesn't duplicate information that may already exist within one's over-arching outline. From an indexing perspective, it also solves the problem of cross referencing information along the axes of the source author, source title, and a large variety of potential subject headings.

And of course if we add even a soupcon of domain expertise in systems theory to the mix...

While thinking about Aktenzeichen, keep in mind that it was used in German public administration since at least 1934, only a few years following Heyde's first edition, but would have been more heavily used by the late 1940's when Luhmann would have begun his law studies.

https://hypothes.is/a/CqGhGvchEey6heekrEJ9WA

When thinking about taking notes for creating output, one can follow one thought with another logically both within one's card index not only to write an actual paper, but the collection and development happens the same way one is filling in an invisible outline which builds itself over time.

Linking different ideas to other ideas separate from one chain of thought also provides the ability to create multiple of these invisible, but organically growing outlines.

We find here juxtaposed the suggestion to use an alphabetic indexing system and that of the Dewey Decimal System with the specific mention that one is grouping cards with similar related ideas.

Did Luhmann evolve his system out of these two ideas and instead of using Dewey, as was apparently not common in Germany, he used a version of the Aktenzeichen ("file numbers") stemming from the 1770s conscription numbers from Vienna?

reply to: https://www.reddit.com/r/Zettelkasten/comments/wrytqj/comment/ilax9tc/?utm_source=reddit&utm_medium=web2x&context=3

Index card systems were insanely popular in the early 1900's for note taking and uses of all other sorts (business administration, libraries, etc.). The note taking tradition of the slip box goes back even further in intellectual history with precedents including miscellanies, commonplace books, and florilegia. Konrad Gessner may have been one of the first to have created a method using slips of rearrangeable paper in the 1500s, but this general pattern of excerpting, note taking and writing goes back to antiquity with the concept of locus communis (Latin) and tópos koinós (Greek).

What some intellectual historians are hoping for evidence of in this particular source is a possible origin of the idea of the increased complexity of direct links from one card to another as well as the juxtaposition of ideas which build on each other. Did Luhmann innovate this himself or was this something he read or was in general practice which he picked up? Most examples of zettelkasten outside of Luhmann's until those in the present, could be described reasonably accurately as commonplace books on index cards usually arranged by topic/subject heading/head word (with or without internal indices).

Perhaps it was Luhmann's familiarity with Aktenzeichen (German administrative "file numbers") prior to his academic work which inspired the dramatically different form his index card-based commonplace took? See: https://hyp.is/CqGhGvchEey6heekrEJ9WA/www.wikiwand.com/de/Aktenzeichen_(Deutschland)

Is it possible that he was influenced by Beatrice Webb's ideas on note taking from Appendix C of My Apprenticeship (1924) which was widely influential in the humanities and particularly sociology and anthropology? Would he have been aware of the work of historians Ernst Bernheim followed by Charles Victor Langlois and Charles Seignobos? (see: https://hypothes.is/a/DLP52hqFEe2nrIMdrd4U7g) Did Luhmann's law studies expose him to the work of jurist Johann Jacob Moser (1701-1785) who wrote about his practice in his autobiography and subsequently influenced generations of practitioners including Jean Paul and potentially Hegel?

There are obviously lots of unanswered questions...

The court file number is used to identify a document and goes back to the file regulations (AktO) of November 28, 1934 and its predecessors.

The German "file number" (aktenzeichen) is a unique identification of a file, commonly used in their court system and predecessors as well as file numbers in public administration since at least 1934.

Niklas Luhmann studied law at the University of Freiburg from 1946 to 1949, when he obtained a law degree, before beginning a career in Lüneburg's public administration where he stayed in civil service until 1962. Given this fact, it's very likely that Luhmann had in-depth experience with these sorts of file numbers as location identifiers for files and documents.

We know these numbering methods in public administration date back to as early as Vienna, Austria in the 1770s.

The missing piece now is who/where did Luhmann learn his note taking and excerpting practice from? Alberto Cevolini argues that Niklas Luhmann was unaware of the prior tradition of excerpting, though note taking on index cards or slips had been commonplace in academic circles for quite some time and would have been reasonably commonplace during his student years.

Are there handbooks, guides, or manuals in the early 1900's that detail these sorts of note taking practices?

Perhaps something along the lines of Antonin Sertillanges’ book The Intellectual Life (1921) or Paul Chavigny's Organisation du travail intellectuel: recettes pratiques à l’usage des étudiants de toutes les facultés et de tous les travailleurs (in French) (Delagrave, 1918)?

Further recall that Bruno Winck has linked some of the note taking using index cards to legal studies to Roland Claude's 1961 text:

I checked Chavigny’s book on the BNF site. He insists on the use of index cards (‘fiches’), how to index them, one idea per card but not how to connect between the cards and allow navigation between them.

Mind that it’s written in 1919, in Strasbourg (my hometown) just one year after it returned to France. So between students who used this book and Luhmann in Freiburg it’s not far away. My mother taught me how to use cards for my studies back in 1977, I still have the book where she learn the method, as Law student in Strasbourg “Comment se documenter”, by Roland Claude, 1961. Page 25 describes a way to build secondary index to receive all cards relatives to a topic by their number. Still Luhmann system seems easier to maintain but very near.

<small><cite class='h-cite via'>ᔥ <span class='p-author h-card'> Scott P. Scheper </span> in Scott P. Scheper on Twitter: "The origins of the Zettelkasten's numeric-alpha card addresses seem to derive from Niklas Luhmann's early work as a legal clerk. The filing scheme used is called "Aktenzeichen" - See https://t.co/4mQklgSG5u. cc @ChrisAldrich" / Twitter (<time class='dt-published'>06/28/2022 11:29:18</time>)</cite></small>

Link to: - https://hypothes.is/a/Jlnn3IfSEey_-3uboxHsOA - https://hypothes.is/a/4jtT0FqsEeyXFzP-AuDIAA

https://www.wikiwand.com/de/Aktenzeichen_(Deutschland)