Folgezettel vs. duplex-numeric arrangement

harr

What was Luhmann's unique contribution to the world of filing systems and card indexes?

Luhmann had a law degree. One of his early jobs was to develop a filing system. It is safe to assume that he was familiar with the best practices of the time.

@chrisaldrich reminded us of Rand Corporation's Progressive Indexing and Filing, a text for courses covering the fundamentals of Indexing and Filing. The fifth edition from 1950 describes a duplex-numeric arrangement, that looks very much like Luhmann's numbering system. Here's the example on page 182:

1        Administration
1-1        Office Maintenance
l-la        Supplies
1-lal        Stationery
1-2        Staff
2        Applications
2-1        Correspondents
2-2        Office Assistants
3        Advertising ‘
3-1        Contracts
3-2        Prospects
4        Manufacturing
4-1        Factory
4-la        Employees
4-1b        Equipment and Supplies
4-1c        Maintenance
4-1d        Stock
4-1d1        Paper
4-2        Job Printing
5        Transportation
6        Educational
7        Publications
7-1        Articles of Interest
7-2        News Items
7-3        Reviews
7-4        Subscriptions
7-4a        Solicitations
8        Associations, Conventions, and Meetings
9        Literature, Requests for
10        Information, Requests for

Did Luhmann use this system or did he invent something new? Luhmann writes (emphasis mine):

The inner workings, the arrangement of the notes, the mind of the Zettelkasten depend on a decision not to order notes by topics and subtopics, and instead choose an order with fixed placement. A content-based system (like a book’s table of contents) would mean that you would have to adhere to a single structure forever (decades in advance!). If you assume that this communication system and oneself can evolve, this will necessarily result in unsolvable problems where to place a note. The fixed-place orderdering doesn’t require topical ordering.

In my opinion Luhmann's main innovation was to break with topical ordering. Rand's example shows what Luhmann explicitly decided against: ordering notes by topics and ever smaller subtopics.

Luhmann continues describing his innovation (emphasis mine):

The fixed-place numbering, abstracted from any content ordering, has several advantages that together enable a higher kind of order.

(1) Free internal branching. You don’t need to add notes at the end, but you can connect them anywhere, even to single words within a text. (…) This enables internal growth of the system without systematic pre-programming and without depending on sequential linearity. The downside is that the original running text may often be interrupted by hundreds of in-between notes; yet, you can easily recover the original context if you are methodological with the numbering. (…)

(2) Opportunity to connect. (…) With this technique it is not important where you place a new note. When there are multiple options you can solve the problem by placing the note wherever you want and create references to capture other possible contexts. (…)

(3) Register. Considering that there is no topical order, you have to put a search mechanism in place because you cannot rely on your numerical memory. (Alternating numbers and letters helps the memory and may be an optical aid when searching notes, but is of course not enough). It is therefore necessary to maintain a keyword index. (…)

The Rand system is aware of content. The content determines the place in the system. Solications are filed under 7-4a.

Luhmann's system is more flexible, but it requires a register — and some trust in serendipity.

chrisaldrich

I'll shortly have a lot more to say on this very subtle historical subject, which I've been work at off and on over the past month or so. My analysis indicates entire lack of innovation on the fronts which you're indicating. Pages 178-180 show the period standard practice of the subject alphabetic filing you say Luhmann was innovating against, but the duplex-numeric is exactly what he was using. The method he chose had been recommended and in use since at least the 1910s—especially for law offices.

Your quotes from his 1981 paper, while interesting, create a false impression stemming from post hoc, ergo propter hoc analysis. You have to remember that by the 1980s, he's been practicing this for nearly 30 years and is providing a reflection on that practice, which is also heavily impacted by his systems theory work through those decades. I strongly suspect that his mid-century perspective didn't stray far from that Remington Rand outline or those of scores of other sources.

It bears noting that of the four potential methods suggested in the chapter, the last one is the Dewey Decimal method, which many who've been in the zettelkasten space have also very naturally tried using as a scaffolding for their filing work. Others have also reasonably suggested variations like the Universal Decimal Classification system or Wikipedia's Academic Outline of Disciplines.

One will also notice that the option of doing a "Variadex Alphabetic" arrangement hasn't ever (to my knowledge) been mentioned in the online zettelkasten space. It was given the pride of place as first in the list of options, but this stems primarily from the fact that it was a variation offered by Remington Rand as a paid product with the related accessories. Every filing cabinet company and major stationery company had variations on this theme with their own custom names and products.