The most dazzling example of co-authorship is Paul Erdős, who co-wrote more than 1400 papers in mathematics with 485 collaborators. (What is your Erdős number?) To do this, he became functionally homeless: “His modus operandi was to show up on the doorstep of a fellow mathematician, declare, “My brain is open,” work with his host for a day or two, until he was bored or his host was run down, and then move on to another home.”
In the sciences, co-authorship is normal. In the humanities, it is uncommon. In philosophy, it is almost non-existent. (See chart.) Yet philosophy is not without famous co-authors (e.g., Marx and Engels). What’s more, some monographs ought properly be considered co-authored, like John Stuart Mill’s collaborations with Harriet Taylor Mill: “when two persons have their thoughts and speculations completely in common it is of little consequence, in respect of the question of originality, which of them holds the pen.”
There is little scholarship on co-authorship in philosophy, but a steady trickle of blog posts suggests that there is interest and anxiety on this point. (Helen de Cruz, Mark Zelcer, Robert Paul Wolff)
1. What is co-authorship generally?
Co-authorship in the sciences is ideally ruled by two rules rooted in a particular sociology of labs and research groups. First, co-authors contribute to the scholarly endeavor for a piece of publishable scholarship by planning, executing, or analyzing the results of some sort of research. Second, co-authors compose the written portion of the research, either collectively or through some division of labor.
Both of these ideals are violated, of course—there are plenty of massive multi-authored articles where scholars receive token authorship (gift authorship) or someone who made substantial contributions is not credited as an author (ghost authorship.) In that way, these are “endorsed” norms, not the “enforced” ones: violations abound and are even legitimated as common practice in some “big science” research areas. But this remains the practical ideal.
2. Why is co-authorship deprecated in philosophy?
Professional philosophers collaborate, usually through disputatious conversation, but usually not in a way that counts multiple thinkers as the author of a single paper. We are also much less likely to cite our peers than the agenda-setting papers in our sub-fields, especially as a part of a generic literature review. (See Kieran Healey’s data.) It is more common for close collaborators to co-edit than to co-author: for instance, Amartya Sen and Martha Nussbaum famously created the “capabilities approach” together without co-authoring any of their foundational papers. They did, however, co-edit the seminal volume, The Quality of Life in 1993.
So while we do not imagine ourselves to be lone geniuses communing with the ancient canon, it is the case that many philosophical papers are projected as manifestos of a single principled thinker. Indeed, philosophers are particularly prone to a kind of “subauthorial collaboration” that is formalized in lavish acknowledgements in the text or an early footnote. (Cronin, Shaw, La Barre, 2003)
David Lewis, who understood philosophical politics as well as anybody (recall), comments on this kind of “ghost” authorship in his paper, “Causation as Influence:”:
“This paper mostly presents the latest lessons I’ve learned from my students. Under the customs of the natural sciences, it should have been a joint paper, the coauthors being (in alphabetical order) John Collins, Ned Hall, myself [David Lewis], L.A. Paul, and Jonathan Schaffer. But under the customs of philosophy, a paper is expected to be not only a report of discoveries but a manifesto; and, happily, the five of us have by no means agreed upon a common party line.”
Yet analytic philosophers often imagine themselves by analogy to the natural and social sciences, and American and continental philosophers increasingly emphasize the collaborative nature of our enterprise. Why, then, do we not use co-authorship more?
One obvious reason is the relative paucity of grants and research support compared to the natural and social sciences. Without an incentive to adopt the lab or research group model, most working philosophers are not members of a funded research unit with reporting requirements. Rigorous research is understood to support ‘research-led teaching,’ and so the single-author model is based primarily on the single-teacher model. We should thus expect the introduction of larger private grant-making institutions, like the Templeton Foundation and the Berggruen Institute, and public European grant agencies, to usher in an era of increasing research group size in philosophy, and the more frequent co-authorship.
We expect that new collaborative technologies will decrease the costs and difficulties of collaboration to the extent that philosophers will more often overcome them, even without any increased funding or benefits. Google Docs, Dropbox Paper, and simple Microsoft Office sharing, versioning, and commenting will all tend to ease the speed with which scholars of all varieties—including philosophers—create collaborative documents. Social media, chat programs, and email ease collaboration over distance to replicate the proximity by which labs and research groups co-compose.
Lastly, we might think of philosophical research as long-shot bets (Langhe and Schliesser, 2017) that explore concepts, methods, or techniques that may be generally applicable. As such, it will be difficult to trace any particular result in the world back to a paper or monograph, and it is preferable to have many such long-shot bets rather than focus the efforts and attention of a highly skilled research team on sequential elaboration of just one of these gambles. It will generally be better to encourage idiosyncratic work done by individuals and small teams in hopes that one of those bets pays off. In the age of increasingly easy collaboration some enduring, virtual small research teams will emerge without, hopefully, fully displacing lone wolfs and disputatious research groups.
3. What norms of co-authorship might philosophers embrace?
If philosophers do adopt co-authorship norms, which ones should we adopt?
We should start with the ideal of recognition of actual contribution to the research and knowing participation in the composition. Co-authorship should never be merely “honorary” inclusion for a member of a team or department who contributed to neither the research work nor the writing endeavor. However, the division of labor in some disciplines has the result of producing co-authored pieces where some credited contributors don’t even understand the paper they have helped to produce. Should we extend co-authorship to a student assistant who writes the literature review for a piece of research without understanding the rest of the paper? Should we accept co-authorship for a paper whose conclusions we do not endorse, if we supplied the formal modeling or computer code that underwrites it?
Our current professional ideal is consensus. On this ideal all authors must give credence to every jot and tittle of the work, even if their confidence varies slightly. Co-authorship in philosophy is stricter because philosophers can and should endorse all the claims, arguments, and conclusions of the paper. Papers can be thus be co-authored in philosophy when two or more researchers find a common interest, discuss it at great length, and truly co-compose the entire paper, contesting each argumentative move and turn of phrase until agreement is reached. As such, it should be very unlikely to see large groups of co-authors writing together, given the difficulty of producing such an exacting meeting of the minds, and we even look askance at philosophy papers co-authored by three or four scholars.
Another possibility is that philosophers working on closely-related research might try to divvy up the tasks in a field of research around some question such that only one or a few of the authors of a work understand the whole thing, while others are credited for their contributions without being “first” or “lead” author status. This requires trust in each other to handle sections of the paper that address relevant issues from their sub-fields; perhaps a paper that is 12,000 words long is written in two halves, with only the introduction and conclusion truly a joint project. On this ideal, co-authors retain to right to veto truly abhorrent claims made outside of their assigned sections, but only by threatening to dissolve the partnership. Otherwise, they can only register objections and hope to be heard.
A third possibility would be to follow the norm in law courts, where empaneled and en banc judges issue both dissenting opinions or in some cases join the majority in parts of their decision but not others, perhaps affirming the result but not all of the methods used to arrive at it. In such cases, a minority might dissent vehemently, while the court is understood to have rendered the opposite verdict: that minority dissent is clearly a separate research project in philosophical terms. They are not understood as co-authors of the majority opinion but as co-authors of a distinct opinion which did not win a majority of support. The more instructive question is what to do when judges affirm parts of the main decision but not all of it, and by analogy, situations where co-authors affirm parts of a research project but not all of it. Can it be possible for one of the co-authors to “sign on” to parts 1, 2, and 4 of a paper, while dissenting from arguments found in part 3 and in the conclusion? For example, in the past one of us has used a footnote to signal an alternative position from the one arrived at in the body of the paper.
A fourth possibility is majority voting. Bright, Dang, and Heesen (2017) argue that scientific work should aggregate researchers’ judgments. Claims and propositions should be made in a paper that receive the assent of the majority of the authors. One might well find oneself outvoted in some cases, and this would be fine so long as there was agreement that voting had not produced a contradictory or logically incoherent set of claims.
A fifth possibility would be a kind of deliberative dictatorship: a lead author could write a paper, assign sections for others to compose, and bounce ideas off of possible co-authors. At the conclusion, all participants who agreed with the final product could sign on as co-authors, while dissenters could produce their own dissenting papers to be published alongside. This is related to proposals that might allow peer reviewers to receive more recognition for their work as initial gatekeepers.
Could all of these modes of co-authorship flourish in philosophy? Are some of them inimical to the discipline?
4. Philosophers should co-author more of our work
Given the fact that some forms of collaborative recognition do exist, why suggest co-authorship as an alternative model for philosophy? Let’s start by dividing the reasons for co-authorship into roughly epistemic and roughly ethical categories, even if this is a division that is easily collapsed. Co-authored papers may simply be better for having multiple composers, readers, and researchers attached to them. The division of epistemic labor will often lead to better-written, more carefully crafted, or simply more copious publications: many minds make light work.
At the same time, co-authorship is partly about recognizing the contributions of our peers. In that sense, it is ethical. This is a weaker defense of co-authorship, since there are alternative methods for providing recognition. If a paper issues from a conversation with a colleague or a good objection raised at a conference or blog post, we philosophers would normally expect to mention that in a footnote, not to grant the colleague or objector co-authorship status. Philosophy papers are sometimes imagined to be the record of the thoughts or analysis of a single agent, and group agency seems much more difficult in these cases because we are so rarely in anything resembling agreement. We are rarely of a single mind, ourselves, so this is no big impediment, but this also ignores the fact that one can commit to a written product while having varying confidence in its disparate elements.
But there’s a significant ethical claim that might recommend co-authorship: the ideal of scholarly friendship. Co-authorship can be a way to channel professional philosophical relationships in productive ways, a norm for guiding conversations and arguments towards shared, potentially overlapping projects. There is independent reason to believe that shared projects are an intrinsic good tied closely to well-being. (Korsgaard, 1992) Thus we should, if possible, prefer to share the tasks associated with philosophical research with others, not just after publication but throughout the scholarly endeavor. Philosophical co-authorship is desirable just because philosophical friendship is desirable.
Shared projects are possible both between equals and between mentors and students. As such, co-authorship is a way to encourage productive collaboration within departments and with undergraduate and graduate students. In the pedagogy-first model of much philosophical research, departmental colleagues at most small schools should not co-author their research because this leads to overlapping areas of interest and knowledge. A department with only a handful of philosophers should instead hope that its faculty have as little in common as possible, even if they must share governance of their department and spend their careers working side-by-side. But if co-authorship underwrites philosophical friendship, then even a maximally pluralistic department should seek opportunities to co-create research, actively seeking agreement and shared methods, research areas, and conceptual terrain.
Like friends, co-authors need not agree on everything. Finding some method for adjudicating those disagreements is important, but philosophical writing can encompass these minor dissents or majoritarian procedures, just as our departments do. The key is that the commitment to co-author—like the commitments of friendship—is a commitment to resolve disagreements using whatever methods are available. Friends do not obsess over decision-procedures, though we adopt them to ease tensions for the sake of shared projects. The same should go for co-authors.
Like friends, co-authors need not be equals. We see in the sciences that co-authorship allows a kind of scholarly mentorship, and in philosophy graduate students experience intense collaboration for the first time while writing their dissertation with a senior scholar. We even acknowledge that this is akin to co-authorship by treating dissertation advising as something close to co-authorship for some professional purposes.
More of this sort of mentorship should be encouraged. The practice of learning from another scholar does not end when a philosopher receives a PhD, and probably we shouldn’t pretend that it does. Perhaps newly-minted PhDs aren’t yet ready for the full burdens of a research program, or perhaps they would benefit from mentorship when they move on to a new research program. Or perhaps not: perhaps this would end with more domination by senior scholars, as the division of labor creates permanent hierarchies. But it’s not as if our current, academic political economy is hierarchy-free.
A final reason is merely accuracy: our authorial norms give a false idea of our practices to the rest of the academy. We should consider revising them to align ourselves with our fellow academics. Let’s not pretend that scholarly productivity metrics are irrelevant or that Deans do not look askance at our publication records compared to other disciplines.
 Despite the best efforts of some of the authors of this post!
 We are indebted to Andrew Corsa’s and Eric Schliesser’s unpublished research on Margaret Fuller’s ideas on friendship and magnanimity.