"Nice piece on plagiarism (assuming it was your own)," someone wrote to me a couple of weeks ago. "You should do a follow up on self-plagiarism, something that I have occasionally perpetrated."
The very concept is peculiar and in some ways more interesting than ordinary plagiarism, which the National Science Foundation defines as "the appropriation of another person’s ideas, processes, results or words without giving appropriate credit." (Striking how both property and propriety come into play in this definition.) The NSF offers no definition of self-plagiarism, which consistency would render a contradiction in terms, like impersonating yourself or picking your own pocket.
Note how lightly the "confession" by my correspondent is tossed out: no rationalization is attempted, nor is one presumed necessary. Someone who has "occasionally perpetrated" plagiarism, in the strict sense, would never admit to it casually, unbidden. As a transgression, plagiarism comes with a fully operational stigma attached.
Not so with self-plagiarism. It can be forbidden but without the benefit of shame as a reinforcement. I did find it denounced as unethical while reading through some 50-odd articles or papers mentioning it, most of them from scholarly journals. At least as frequent, though, were suggestions that a certain amount of self-plagiarism is inevitable -- and perhaps even necessary.
My sampling included a great many articles that mentioned self-plagiarism in passing. But let's start with those that did and were not indulgent. The most forthright statement against it appeared in The American Journal of Nursing in 2002, written by Diana J. Mason, then the journal's editor in chief. She devoted most of one of her editorials to instructing prospective contributors on the basics of adequate citation. The paragraph on self-plagiarism is brisk and precise:
If your original work is published by one publisher, and subsequent works in which you use the same words are published by another, you're probably violating copyright law. If your publisher is the same for both the original and subsequent self-plagiarized works, you're still guilty of intellectual dishonesty. Readers must be able to trust that writers aren't misrepresenting the originality of the material.
Laurie Stearns made a similar point in "Copy Wrong: Plagiarism, Process, Property, and the Law" in a 1992 California Law Review article. She defined self-plagiarism as the "misrepresentation … not of authorship but of the novelty of the copied work," with potential harm to the public. Readers "invest time or money in a work with the expectation that its contents are different from, or at least differently expressed than, the contents of the author's other works." She noted that recycling part of something you have already published could be -- as Mason stressed in her editorial -- a violation of the copyright covering the earlier work, But Stearns also identifies self-plagiarism as a failure to meet the terms of an implicit contract between writer and reader.
Unfortunately she assumes that the terms of that contract will be obvious to all parties involved, while her notion of what constitutes a breach remains vague. "Self-plagiarism occurs when a work echoes an earlier work by the same author," she explains at one point. (Well, there goes the English department.) The statement that readers approach a text "with the expectation that its contents are different from, or at least differently expressed than, the contents of the author's other works" applies to only certain reading publics. The relationship between author and reader is not always that of vendor and client; even when it is, novelty is not necessarily part of the bargain.
Scientific self-plagiarism comes in a range of shades of gray -- with duplicate publication being the most blatant. It sounds like an outgrowth of the typically frowned-upon and often proscribed practice of dual submission of a paper to more than one journal, then publishing it in the one that first accepts it. Duplicate publication carries things a step further by not withdrawing the paper from consideration elsewhere, or submitting it under different titles and counting each acceptance as a separate publication.
Other, only marginally less egregious forms of self-plagiarism come up in Peter Woelert's "The 'Economy of Memory': Publications, Citations, and the Paradox of Effective Research Governance" (Minerva, 2013). One is generating a "new" paper through "a slight modification of some theoretical or empirical aspect of a paper" the same authors have already published. Besides repackaging, there is "salami slicing": creating "strategically produced redundant publications" through piecemeal publication of research findings in numerous venues, "often to the detriment of the scope, depth and coherence of the published content." For more on this issue, see Christine Urbanowicz and Beth A. Reinke's paper in The Bulletin of the Ecological Society of America for October 2018, under the memorable title "Publication Overlap: Building an Academic House with Salami Shingles."
The idea that self-plagiarism might be unacceptable yet also the product of creditable motives informs "Dante’s Inferno: Seven Deadly Sins in Scientific Publishing and How to Avoid Them," a multiauthored paper in a book called Publishing Addiction Science: A Guide for the Perplexed (Ubiquity Press, 2017). A researcher who nailed it in writing the literature review or methods section in an earlier report -- and eager to get down to his or her latest findings -- may well be tempted by the convenience of cut-and-paste. The multiple authors of the chapter advise "chang[ing] some of the wording in each sentence" and making sure that the earlier work is adequately cited. This would at least avoid giving a misleading impression of how much new work has gone into the paper.
As for those authors putting in a good word for plagiarism, we'll take them up sometime early in the new year.