How Much is Too Much?

[Note: This was originally published on Monday, then accidentally deleted yesterday, and now re-published today. Apologies!]

Two anonymous readers write asking about self-plagiarism:

(#1) I’m been wondering lately about “self-plagiarism” and to what extent it is acceptable to reuse material from ones own previous papers. It seems to me that this is actually quite common in philosophy, but I wonder how to approach editors about this.

I’m thinking of submitting a paper to anthology, and (maybe) later another paper to a journal. The latter paper would reuse material from the anthology-paper, but develop it in a slightly different direction. To what extent would this be acceptable? Should one alert the journal editor about this and ask whether it is okay?

I realise that there are copyright issues here, but my question is more about the ethics of self-plagiarism. I would be interesting to hear what editors think about this.

(#2) What’s protocol for submitting two articles that have a significant amount of overlapping content (say, a page) to separate journals? The articles, as I am imagining the situation, are otherwise significantly different.

There are three sorts of contexts where the issue of self-plagiarism generally arises. The first is when you have the same material that you want to present to two, mostly disjoint, audiences. The second is when you are presenting new material which builds on previous material you’ve already published. The third is when you are presenting new material inspired by the same background setting as something you’ve previously published (even if the new paper doesn’t explicitly build on the previous publication).

Since I work in a field where I publish to two almost disjoint audiences (history of logic and mathematical logic), I face all of these situations regularly. In almost every paper I write, before I can present the new and interesting material, I have to provide some historical, expository information. (Once you’ve written more than a few papers on obligationes, it becomes very hard to present the same background material in new and exciting ways! But since my audience is rarely historians, I can’t assume any of them already know anything about the genre.) So I’ve developed a few personal guidelines:

  • There should be as little verbatim material as possible. (You cannot be sure that you won’t end up having overlapping readers — especially if the readers of the second paper are assiduous in following up references to the first — and no one likes to read exactly the same paragraph over and over.) If you can rewrite the material, even a little bit, do so.
  • Where you can get away with simply referencing the previous paper, do so. (This is easier to do when what you’re referencing is, e.g., previously proven theorems.)
  • Be explicit. If the argument has appeared in print in a different version, say so.
  • Ask yourself what you hope to gain by re-packaging the argument and presenting it to a new audience. What can the new presentation give your new audience that they wouldn’t be able to get from the previous one? What do they gain? This can be either the addition of necessary background information that was assumed in the original paper, the augmentation of the paper with new arguments, responses to criticisms raised to the previous paper, discussion of how the subject of the paper is relevant to the interests of the new audience, etc.

There is no hard-and-fast quantitative guideline that can be given as to “How much overlap is too much.” Any attempt to give such a quantitative rule (“75% is too much”; “50% is too much”; “25% is too much”; “any is too much”) could only be justified by circling back to the motivation behind both of the questions above. These questions arise from the stand-point that plagiarism is bad — a foundation that I think all agree on. In my opinion, whether the work being plagiarised belongs to the person who is plagiarising or to another does not really matter: The standards of what counts as plagiarism should be the same in both cases. (I know not everyone agrees with this, and invite dissenting arguments in the comments!) But before one can say “how much (self-plagiarism) is too much”, we need to first consider why plagiarism is frowned on, because this differs between self- and non-self-plagiarism. Plagiarising someone else’s thoughts is an attempt to appropriate for your own credit something due to someone else. Plagiarising your own thoughts is an attempt to receive credit twice for the same idea.

This gives us an important distinction for the question of “how much is too much”: Ideas. There is a qualitative difference between self-plagiarism of arguments and self-plagiarism of expository matter, with the former being significantly more problematic than the latter. In fact, for the most part, the latter is going to be almost completely unproblematic, so long as it is restricted in amount and the other guidelines I suggest above taken into account, and this is because if you’re writing more than one paper in the same subject material, there is no way to escape the need to present the same expository information in more than one paper. But in a profession like philosophy where publications matter so much, a problem arises in when there is an appearance that an author is attempting to double-dip, that is, to get two papers for the “price” of a single idea.* So what you want to do is show — both to your reader and to the editor — that you are cognizant of this, and you are trying to offer more than the same paper repackaged different.

The moral of the story: Cite your sources. Be explicit about what you are re-using. Say how the derivative piece goes beyond the original. Document, document, document, and then let the editor make the final decision as to whether there is too much overlap. Then the question becomes not one of “does this paper exhibit plagiarism” but one of “does this paper provide sufficient new and interesting content to warrant publication?”


*. This is a norm that differs from field to field. In computer science, for example, it is completely routine for large portions of papers published in conference proceedings to be lifted with minimal change into journal articles which extend the conference results substantially. But these cases are nevertheless still explicitly marked: The journal article will include in its acknowledgements or in the introduction a statement that it is an extended version of one or more conference papers, with full citations.


2 thoughts on “How Much is Too Much?

  1. elisa freschi

    Just a small addition to an excellent post. I guess I am not the only one who deals with the following problem: I frequently work on less-known authors, schools or problems. This means that I need to add a few paragraphs to each article explaining who is the one I will be talking about (where/when did he live, with whom was he in touch, which religion did he follow, etc.?) or why a certain issue was relevant in a certain context (the standard example would be that of the nature of angels in Medieval Europe) and so on.
    In many cases, this means re-writing more or less the same things when I write about, say, “V’s theory of free will” and “V’s and R’s theories of God’s relation with individual souls” and “M’s theory of free will”.

    1. Sara L. Uckelman

      Yes — it’s basically impossible to get away from repeating yourself when it comes to this sort of expository information. And once you’ve found one clear and concise way of presenting it, it can be really hard to come up with other, equally clear and concise ways! (At least this is what I find). But I think this sort of overlap, so long as it is minimal, will almost never be considered a problem.


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