What's A "Zettlekasten" (Oh, no, not again!)?

harr · August 11

@ZettelDistraction said:
The non-existence of such a predicate does not yield the absence of common understanding: the term "Zettelkasten" is a prototype/exemplar term, and objects resemble the exemplar to a greater or lesser extent.

Not sure if I understand you correctly. Do you mean:

There's a common understanding in this community that the term "Zettelkasten" refers to objects that resemble Luhmann's personal Zettelkasten to a greater or lesser extent?

Or do you mean:

There's a common understanding in this community that the term "Zettelkasten" refers to an ideal form and that objects can resemble that form to a greater or lesser extent?

Edmund · August 11

@ZettelDistraction said:
Ahrens’s categories imply the definition: a main note is a permanent note that is not a literature note.

A perfect definition! Thank you.

harr · August 11

@Edmund said:

@ZettelDistraction said:
Ahrens’s categories imply the definition: a main note is a permanent note that is not a literature note.

A perfect definition! Thank you.

If you're also interested in a literal quote from Ahrens's book (2nd edition, chapter 6, emphasis added):

The only permanently stored notes are the literature notes in the reference system and the main notes in the slip-box. The former can be very brief as the context is clearly the text they refer to. The latter need be written with more care and details as they need to be self-explanatory.

tomp · August 11

@harr said:

@tomp said:
If you think all I want is a tool for taking notes you haven't been paying attention.

As far as I know, you're interested in building a Personal Knowledge Management Systems (PKMS) using some principles that you trace back to Niklas Luhmann.

As I wrote, you haven't been paying attention.

Something I don't understand about the story: Why did the king ask specifically for a goose and not more broadly for large waterfowl?

Because he was learned but not wise, I expect.

harr · August 11

@tomp said:
Because he was learned but not wise, I expect.

I agree, if you mean an incurious person, who had once picked up a few big words without really learning something.

A wise king, who wanted to learn more about biology, might have asked his advisors: "Tell me. How do biologists distinguish different Anatidae species? Show me. How do you determine the species of this bird?"

A wise king, who just wanted a good meal, might have asked his cook for suggestions. :-)

Edmund · August 11

@harr said:

@Edmund said:

@ZettelDistraction said:
Ahrens’s categories imply the definition: a main note is a permanent note that is not a literature note.

A perfect definition! Thank you.

If you're also interested in a literal quote from Ahrens's book (2nd edition, chapter 6, emphasis added):

The only permanently stored notes are the literature notes in the reference system and the main notes in the slip-box. The former can be very brief as the context is clearly the text they refer to. The latter need be written with more care and details as they need to be self-explanatory.

It's a perfect definition—for a complicated structure—and it helped me to search for a simplified one:

Some of us might say that they are all Zettel. So true!

ZettelDistraction · August 11

@harr said:

@ZettelDistraction said:
The non-existence of such a predicate does not yield the absence of common understanding: the term "Zettelkasten" is a prototype/exemplar term, and objects resemble the exemplar to a greater or lesser extent.

Not sure if I understand you correctly. Do you mean:

There's a common understanding in this community that the term "Zettelkasten" refers to objects that resemble Luhmann's personal Zettelkasten to a greater or lesser extent?

Or do you mean:

There's a common understanding in this community that the term "Zettelkasten" refers to an ideal form and that objects can resemble that form to a greater or lesser extent?

Neither. Both alternatives replace my claim about what does not follow with a positive claim about consensus within this community. My position is stated in Zettelkasten as a Family-Resemblance Category.

ZettelDistraction · August 11

@Edmund said:

@ZettelDistraction said:
Ahrens’s categories imply the definition: a main note is a permanent note that is not a literature note.

A perfect definition! Thank you.

You're welcome.

Ah, I am beginning to follow your diagrams. I had not appreciated how clarifying they are.

harr · August 11

@ZettelDistraction said:
My position is stated in Zettelkasten as a Family-Resemblance Category.

Excellent work! I appreciate this part:

Claims intended to cover all Zettelkasten systems may require an explicit scope. That requirement is compatible with common understanding in ordinary discussion. It distinguishes the lack of a universal definition from the lack of a shared subject.

Thanks for making that distinction. I like the terminology: "common understanding" of a "shared subject" in "ordinary discussion" vs. "universal definition".

harr · August 11

With @ZettelDistraction's terminology in mind, I advocate in this debate for scoped definitions.

Those definitions don't try to cover "every historical object and every application of the words".¹ They are limited to an explicitly declared scope. Within that scope they allow for Boolean tests.

https://github.com/flengyel/Zettel/wiki/Zettelkasten-as-a-Family-Resemblance-Category/a100f1c61edea6d6ba3e9ef31b3086ecc195c8f2 ;↩︎

ZettelDistraction · August 11

In https://github.com/flengyel/Zettel/wiki/Zettelkasten-as-a-Family-Resemblance-Category/19a9ac9201c341d964ac4171597cbf69425b5cfc I have corrected two misleading sentences in the Wittgenstein section, to which I have added Wittgenstein's beetle in a box.^†

It only took five years to get the Zettel Wiki to its present form. I don't require Boolean predicates, but I don't disallow them either. After a day spent on staking out our positions and finding an agreed-upon vocabulary, I must return to the interminable revision of a mathematical paper.

^†Not the actual beetle, assuming there was one.

Sascha · August 12

@Edmund said:

@ZettelDistraction said:
Ahrens’s categories imply the definition: a main note is a permanent note that is not a literature note.

A perfect definition! Thank you.

Caution: A definition shouldn't be of negative nature if it could be of positive nature. (Copi 1998, 60)

Copi, Irving (1998): Einführung in die Logik, UTB

Sascha · August 12

@Sascha said:

@Edmund said:

@ZettelDistraction said:
Ahrens’s categories imply the definition: a main note is a permanent note that is not a literature note.

A perfect definition! Thank you.

Caution: A definition shouldn't be of negative nature if it could be of positive nature. (Copi 1998, 60)

Copi, Irving (1998): Einführung in die Logik, UTB

Perhaps, I should add a bit more explanation to that: The negative definition of a main note provides the extension that is inferred by the negation. But we are looking for the intension of the term.

Or put differently: A definition should be based on the formula by which we decide whether an object is part of the set.

harr · August 12

@Sascha said:
Caution: A definition shouldn't be of negative nature if it could be of positive nature. (Copi 1998, 60)

A later edition, Copi et al. (2019), lists this rule together with four others in Chapter 3.6 Definition by Genus and Difference:¹

A definition should state the essential attributes of the species.
A definition must not be circular.
A definition must be neither too broad nor too narrow.
Ambiguous, obscure, or figurative language must not be used in a definition.
A definition should not be negative when it can be affirmative.

@Sascha said:
The negative definition of a main note provides the extension that is inferred by the negation. But we are looking for the intension of the term.

@ZettelDistraction's definition refers to Ahrens' system, not yours. In Ahrens' system there are only two types of permanent notes: literature notes and main notes. If a permanent note is not a main note, it must be a literature note. If a permanent note is not a literature note, it must be a main note.

My main argument for @ZettelDistraction's approach is that it is much easier to state essential attributes for literature notes than for main notes. As I understand Ahrens: literature notes are about exactly one item of literature; they contain the bibliographical data that identifies the item plus some personal conmments. With literature notes out of the way, every other permanent note is—by negative definition—a main note.

The scope of this definition is only Ahrens' system. If you prefer other definitions for your system, I'm curious to learn more about those definitions.

Irving M. Copi, Carl Cohen, Victor Rodych: Introduction to Logic. 15th edition. Taylor & Francis, 2019. ↩︎

Sascha · August 12

@harr You didn't provide an argument but just reworded the negative definition with more words.

Edmund · August 12

Our discussion prompted me to reread Ahrens's book from 2022. Now I have a visual definition on one page:

I didn't get this insight from my first reading: The 'Smart Notes' are distributed across four different physical locations. My own Zettelkasten focuses on just one location. All notes are within one system. Obsidian.

Unfortunately, the definition ‘A main note is a permanent note that is not a literature note.’ no longer contributes significantly to our understanding.

ZettelDistraction · August 12

@Sascha said:
@harr You didn't provide an argument but just reworded the negative definition with more words.

@harr did provide an argument. Literature notes are easier to characterize within Ahrens’ system, and the proposed negation is relative to notes in that system rather than to everything whatever.

Copi’s rule is that “[a] definition should not be negative when it can be affirmative.” This is a preference, not a prohibition. Copi goes on to allow that, once the genus has been stated affirmatively, a species may sometimes be characterized by excluding the other species of that genus (Copi, Cohen, and McMahon, pp. 100–101). @harr’s argument fits that pattern. Ahrens’s permanent notes divide into exactly two categories, literature notes and main notes. Once literature notes have been characterized, every other permanent note is therefore a main note. This is not merely a rewording of the negative definition; it identifies the genus, establishes its two species, and explains why exclusion determines the second species..

The definition is an ordinary relative complement. If $(P)$ is the set of permanent notes in Ahrens’s system and $(L\subseteq P)$ is the set of literature notes, then the set of main notes is $(P\setminus L)$. The affirmative genus is fixed, and Ahrens’s classification leaves exactly two species within it. Characterizing one species leaves the other.

Suppose, nevertheless, that affirmative properties are required. Ahrens supplies clues from which one might try to assemble a positive characterization of main notes: they can be linked to one another, which suggests that they possess unique identifiers, and they are written as if for print. (A search on “identifier” leads only to “digital object identifier (DOI).”) He also suggests a standardized format without specifying one, although the second edition supplies Luhmann’s cards as examples.

What one finds scattered through How to Take Smart Notes is closer to a collection of suggestions than to a definition. I hesitate turning those remarks into a positive list of necessary and sufficient attributes because doing so risks attributing to Ahrens a systematic account that he does not give.

harr · August 12

@Edmund said:
Unfortunately, the definition ‘A main note is a permanent note that is not a literature note.’ no longer contributes significantly to our understanding.

Maybe it becomes clearer, when you make one tiny change in your drawing: replace the term "Permanent Notes" with "Main Notes".

The following image was created by my favorite bot. It shows two wooden boxes with permanent notes. The small box contains the literature notes, the big box the main notes. I chose a napkin as fleeting note, because fleeting notes ("flüchtige Notizen") are supposed to be thrown away quickly.

Edit: Does anybody know, where Ahrens recommends to file the index ("Schlagwortregister")? I couldn't find it in the book.

ZettelDistraction · August 12

I missed the edit window to make this correction:

Suppose, nevertheless, that affirmative properties are required. Ahrens supplies clues from which one might try to assemble a positive characterization of main notes: they are written as if for print, and they can be linked to one another, which suggests that they possess unique identifiers. However, a search on “identifier” leads only to “digital object identifier (DOI)”--I could not locate a description or definition of note identifiers in Ahrens. He also suggests a standardized format without specifying one, although the second edition supplies Luhmann’s cards as examples.

ZettelDistraction · August 12

@Edmund said:
Our discussion prompted me to reread Ahrens's book from 2022. Now I have a visual definition on one page:

The notes are allocated among four locations by category. Location alone doesn't give you a typology; otherwise you could randomly shuffle the notes into the four locations and declare the main notes to be the notes that ended up in the slip box. This is conceptually useless. And then everything in your Obsidian vault is an "Edmund note" if we go by location only.

Unfortunately, the definition ‘A main note is a permanent note that is not a literature note.’ no longer contributes significantly to our understanding.

You could follow @harr's suggestion to replace "Permanent Note" with "Main Note." The Permanent Note illustration already differentiates them from Literature Notes in line with Ahrens.

Edmund · August 12

@harr said:
Edit: Does anybody know, where Ahrens recommends to file the index ("Schlagwortregister")? I couldn't find it in the book.

Page 19:

Sascha · August 13

@ZettelDistraction said:

@Sascha said:
@harr You didn't provide an argument but just reworded the negative definition with more words.

@harr did provide an argument. Literature notes are easier to characterize within Ahrens’ system, and the proposed negation is relative to notes in that system rather than to everything whatever.

No, he doesn't. That literature notes are easier to characterize (which I don't follow, but given this) is not an argument it is a statement with no argument using it. The proclamation that a statement is a reason is not sufficient to form an argument.

Suppose, I tell you that your squat form is bad and will lead to injury (showing you how what you are doing put you in bad form). Is it acceptable that you say "But it is easier!"?

Or shorter: Incorrect action, won't become correct if it is easier than the correct action.

Copi’s rule is that “[a] definition should not be negative when it can be affirmative.” This is a preference, not a prohibition. Copi goes on to allow that, once the genus has been stated affirmatively, a species may sometimes be characterized by excluding the other species of that genus (Copi, Cohen, and McMahon, pp. 100–101). @harr’s argument fits that pattern. Ahrens’s permanent notes divide into exactly two categories, literature notes and main notes. Once literature notes have been characterized, every other permanent note is therefore a main note. This is not merely a rewording of the negative definition; it identifies the genus, establishes its two species, and explains why exclusion determines the second species..

The genus is a necessary condition, but it is not sufficient. Identifying the genus is not enough to qualify a negative definition. Or, coming back to squats: Moving the weight up and down doesn't mean that you squat.

The definition is an ordinary relative complement. If $(P)$ is the set of permanent notes in Ahrens’s system and $(L\subseteq P)$ is the set of literature notes, then the set of main notes is $(P\setminus L)$. The affirmative genus is fixed, and Ahrens’s classification leaves exactly two species within it. Characterizing one species leaves the other.

I gave you specific reasons why a negative definition is not doing the trick here. I should've quoted the first rule: A definition should state the essential attributes of the species.

When we ask about what a main note is, we ask for the intension of the term and not its extension. With the negative definition, you covered the extension, but not the intension [emdash] the actual epistemic interest.

Or does the negative definition instruct you how to practically apply the concept of the main note (e.g. writing the note)?

Edmund · August 13

@harr said:
I suggest to reduce complexity by narrowing the scope of the question. For example:

...

Focus on individual systems. Don't talk about Zettelkasten in general, but about person X's Zettelkasten and person Y's Zettelkasten. That should reduce recurring discussions about who's more correct, X or Y. :-)

Let me start a list:

Luhmanns' Zettelkasten
Fasts' Zettelkasten 2013
Ahrens' Zettelkasten
Allossos' Zettelkasten
Dotos' Zettelkasten
Fasts' Zettelkasten 2025 (Any changes?)
Viczians' Zettelkasten
My own Zettelkasten

The 'Zettelkasten Evolution Map' focuses on the Zettel naming:

The concept map from analytical reading focuses on 'Toolsets and Types of Notes'. As a first example let's have a look at 'Ahrens' Zettelkasten':

Can you tell me if my Zettelkasten is any different from yours?

Edmund · August 13

@harr said:

@Edmund said:
Unfortunately, the definition ‘A main note is a permanent note that is not a literature note.’ no longer contributes significantly to our understanding.

Maybe it becomes clearer, when you make one tiny change in your drawing: replace the term "Permanent Notes" with "Main Notes".

For me it depends on the source:

'Permanent Notes' is a term used with Ahrens' Zettelkasten.
'Main Notes' is a term used with Dotos' Zettelkasten.

And Luhmann would call it 'Zettel'.

See also: https://forum.zettelkasten.de/discussion/comment/26057/#Comment_26057

harr · August 13

@Edmund said:
For me it depends on the source:

'Permanent Notes' is a term used with Ahrens' Zettelkasten.

'Main Notes' is a term used with Dotos' Zettelkasten.

Are we reading the same sources?

These screenshots are from the 2nd english edition (2022):

These are from the original German edition (2017):

ZettelDistraction · August 13

@Sascha said:

@ZettelDistraction said:

@Sascha said:
@harr You didn't provide an argument but just reworded the negative definition with more words.

@harr did provide an argument. Literature notes are easier to characterize within Ahrens’ system, and the proposed negation is relative to notes in that system rather than to everything whatever.

No, he doesn't. That literature notes are easier to characterize (which I don't follow, but given this) is not an argument it is a statement with no argument using it. The proclamation that a statement is a reason is not sufficient to form an argument.

@harr did provide an argument. Here it is:

Copi permits a negative definition when an affirmative definition is unavailable.
Ahrens characterizes literature notes affirmatively.
No affirmative definition of main notes is available in Ahrens: Ahrens’s scattered positive remarks do not amount to one.
Ahrens divides permanent notes into literature notes and main notes.
Therefore, defining main notes as the permanent notes that are not literature notes satisfies Rule 5 and determines the remaining species.

The argument can be challenged, but it cannot be dismissed as no argument.

Suppose, I tell you that your squat form is bad and will lead to injury (showing you how what you are doing put you in bad form). Is it acceptable that you say "But it is easier!"?

Or shorter: Incorrect action, won't become correct if it is easier than the correct action.

Neither @harr nor I made the claim that an incorrect definition becomes correct because it is easier. The claim about ease explains why one might characterize one of the two categories affirmatively and obtain the other by exclusion. It is not the basis for the classification.

The genus is a necessary condition, but it is not sufficient. Identifying the genus is not enough to qualify a negative definition. Or, coming back to squats: Moving the weight up and down doesn't mean that you squat.

We have identified the genus, established that Ahrens divides it into exactly two species, and characterized one of those species. Copi explicitly allows that, once the genus has been stated affirmatively, a species may sometimes be characterized by excluding the other species. His qualification that this is rarely possible is satisfied unusually well here because the genus has exactly two species.

The definition is an ordinary relative complement. If $(P)$ is the set of permanent notes in Ahrens’s system and $(L\subseteq P)$ is the set of literature notes, then the set of main notes is $(P\setminus L)$. The affirmative genus is fixed, and Ahrens’s classification leaves exactly two species within it. Characterizing one species leaves the other.

I gave you specific reasons why a negative definition is not doing the trick here. I should've quoted the first rule: A definition should state the essential attributes of the species.

When we ask about what a main note is, we ask for the intension of the term and not its extension. With the negative definition, you covered the extension, but not the intension [emdash] the actual epistemic interest.

The set equation records the extension, but the definition itself is intensional: “permanent note” names the genus, and “not a literature note” supplies the specific difference. Equivalently, M(x)↔P(x)∧¬L(x) states the conditions under which an object belongs to the category. The presence of negation does not turn a definition by genus and difference into a mere enumeration of its extension.

Or does the negative definition instruct you how to practically apply the concept of the main note (e.g. writing the note)?

Whether the definition instructs someone how to write a main note is a different question. A definition need not be a procedure for producing its instances. Ahrens does say that main notes are self-contained and written as if for print, but these scattered remarks do not amount to a positive list of necessary and sufficient attributes or a standard format. My article was written to settle Ahrens’s terminology, not to supply the writing instructions that Ahrens leaves unspecified.

To address that question in my own system, I stipulated a note format in the Zettel repository, but it is not Ahrens’s format; Ahrens does not specify one.

ZettelDistraction · August 13

@Edmund said:

@harr said:
I suggest to reduce complexity by narrowing the scope of the question. For example:

...

Focus on individual systems. Don't talk about Zettelkasten in general, but about person X's Zettelkasten and person Y's Zettelkasten. That should reduce recurring discussions about who's more correct, X or Y. :-)

Let me start a list:

Luhmanns' Zettelkasten

Fasts' Zettelkasten 2013

Ahrens' Zettelkasten

Allossos' Zettelkasten

Dotos' Zettelkasten

Fasts' Zettelkasten 2025 (Any changes?)

Viczians' Zettelkasten

My own Zettelkasten

The 'Zettelkasten Evolution Map' focuses on the Zettel naming:

In 2020, I had already pointed out Ahrens's use of the term "main notes" as follows:

Ahrens refers to these notes as “the main notes in the slip-box” in exactly one place (Ahrens, 44). Since Ahrens doesn’t provide examples of Zettels or offer a standard template for notes, I offer a template for free at https://github.com/flengyel/Zettel.

That was a reference to the first edition of How to Take Smart Notes. In the second edition, Ahrens presents an example from Luhmann's Zettelkasten. Incidentally, the page number (p. 44) to the cited text is the same in the 2017 and 2022 English translations of How to Take Smart Notes.

Subsequent revisions of From Fleeting Notes to Project Notes are more focused and point out that Permanent notes divide into Literature Notes and Main Notes, in Ahrens's terminology.

Also, scoped definitions of “Ahrens’s Zettelkasten,” “Doto’s Zettelkasten,” and so forth are useful, but they do not replace the general family-resemblance category. The broader discourse remains intelligible because these systems are compared through shared historical and functional resemblances. That's my position, for what it's worth.

harr · August 13

Thanks, @ZettelDistraction! I was drafting a similar post. :-)

Maybe @Sascha needs to spelled out, that I was comparing two alternatives? When I wrote (emphasis added) …

My main argument for @ZettelDistraction's approach is that it is much easier to state essential attributes for literature notes than for main notes."

… I was comparing two options:

state essential attributes for literature notes (L)
state essential attributes for main notes (M)

@Sascha seems to be believe, that I had to state all premises explicitly, because I used the word "argument". However according to Copi, this is not a requirement. Copi teaches readers to pay attention to premises in context and non-formal wording. (Thanks for summarizing them for the less attentive readers!)

However, I left an important premise unstated. You noticed it and thankfully provided it in a later post:

What one finds scattered through How to Take Smart Notes is closer to a collection of suggestions than to a definition. I hesitate turning those remarks into a positive list of necessary and sufficient attributes because doing so risks attributing to Ahrens a systematic account that he does not give.

Not sure, if @Sascha actually cares about arguments and definitions within our narrow scope. He tries to expand the scope to "actual epistemic interest" and "how to practically apply the concept of the main note".

I'm also not sure, if he understands the term intension in Copi's sense. Copi (p. 82) writes:

The set of attributes shared by all and only those objects to which a general term refers is called the intension (or connotation) of that term.

Why do I find it easier to come up with an intension for L than M? Because Ahrens doesn't provide "attributes shared by all and only those objects" to which main note refers. He talks rather vaguely about "own thoughts". For literature notes however, Ahrens repeatedly mentions two attributes. In the German edition he writes about a) "Quellenangaben" or "bibliographische Angaben" and b) "Literaturextrakte" or "Lektüreextrakte".

harr · August 13

@ZettelDistraction said:
Also, scoped definitions of “Ahrens’s Zettelkasten,” “Doto’s Zettelkasten,” and so forth are useful, but they do not replace the general family-resemblance category. The broader discourse remains intelligible because these systems are compared through shared historical and functional resemblances. That's my position, for what it's worth.

I agree. I think that both discourses benefit from each other. Small-scope discourse provides well-sourced data for the broader discourse. The broader discourse provides a useful context for small-scope discourse.

Edmund · August 13

@harr said:

@Edmund said:
For me it depends on the source:

'Permanent Notes' is a term used with Ahrens' Zettelkasten.

'Main Notes' is a term used with Dotos' Zettelkasten.

Are we reading the same sources?

Here the 2nd edition of the book I'm reading: https://www.amazon.de/How-Take-Smart-Notes-Technique/dp/8197022275/

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