Catarina: Well, I have not co-authored that many papers actually; the paper I finished yesterday is only my fourth co-authored paper. In each case, the process has been somewhat different. My first co-authored paper was written with Stephen Read: we realized that we both intended to speak on a very similar topic at a given conference, so he proposed that we do it together. Basically, he wrote his part and I wrote mine, but we were very much in agreement on the basic thesis from the start. My second and third co-authored papers were written with my friend and former colleague Edgar Andrade; the first one started when Edgar (who has a mathematics background) came to me with some results on different semantics for syllogistic and asked what the results meant philosophically. From there on, the process was truly collaborative; it was laborious and time-consuming, but I do think it is one of the best papers I've ever written, and precisely thanks to the collaboration. The other paper with Edgar was actually mostly written by him on the basis of some results we had proved together on Brandom's notions of entailment; I was mostly 'coaching' the writing process. (All papers available on my website.)
For this fourth paper, co-authoring was a real life-saver! I had committed to writing a paper on syncategoremata for a volume being edited by Margaret Cameron and Rob Stainton for OUP, but due to difficult personal circumstances earlier this year, I had not been able to work on it when I had intended to. Syncategoremata is not a topic I've done that much work on, so although I had in mind the philosophical-historiographical thesis that it is a mistake to understand medieval syncategoremata as corresponding to the modern notion of logical constants, I would still have to do my homework and study the medieval texts more carefully. I then realized that the only way I could still finish the paper within the deadline was to join forces with Joke Spruyt, who has herself extensively worked on the syncategoremata literature. So she took an extended abstract I had written arguing against the syncategoremata-logical constants conflation as her starting point, and went on to provide a precise overview of the medieval literature which nicely illustrates the thesis. I finished up by expanding on the abstract and adding a second part with a systematic comparison between the two notions.
Brit: I agree with the perception that hiring-, tenure- and promotion-committees tend to give less weight to co-authored papers. But they really shouldn't, as they are much harder to do and often end up being of higher quality.
We need a convention similar to that in the sciences. First-author did the work. Last author is the lab-owner and overall director of the project. Everyone in between contributed in some lesser sense. Sometimes there is more than one "first-author". Then you add a footnote saying that so-and-so and so-and-so contributed equally to the project, or something to that effect. If we had some established conventions, we could avoid the hiring and promotion problems.
Another issue I just thought about recently is that of how much weight to assign to a paper co-authored with the person's supervisor (while in grad school). I think I have come to the conclusion that in virtually every one of those cases the grad student did most of the work, the thinking, etc. What I really like is when I am on a hiring committee and get a letter from someone's supervisor and then see that they co-authored something together. That makes me believe the praise in the letter to a greater extent.
Do you have any thoughts on how to make conventions for co-authored papers in philosophy? And what's your take on papers co-authored by graduate student and supervisor?
Catarina: I agree with you that, when I see that a graduate student has co-authored a paper with her/his supervisor, this strikes me as a sign of the high regard that the supervisor has for the student. So I couldn't agree more with you here. But I suppose some people think differently about it, and think instead that the supervisor must have done all the work and the student is just in it for a free ride. My impression is that only very awkward supervisors are likely to do such a thing... Instead, it's more likely that the student did most of the work and that the supervisor is in it for a cheap, if not free, ride.
As for adopting conventions for co-authoring in philosophy, I am very skeptic that we could have anything like the system that is in place in the empirical sciences. I am under the impression that there is already a bit of a convention among the more techy areas of philosophy, according to which the first author is the one who came up with the technical results, but I may be wrong on this. But the issue is that co-authoring formats in philosophy are very varied, nothing like the more or less standard way to proceed in the empirical sciences that you describe. So my best shot is: what we could do is to add a footnote at the beginning of a co-authored paper explaining who did what and why the order of authors is what it is -- like the famous Clark-Chalmers opening footnote!
And what about co-authoring with people working in different areas? I know you are currently working very closely with a number of cognitive scientists. On my methodologically pluralistic conception of philosophy, working together with people from other areas and fields is very much an ideal to be pursued, in the general spirit of teaming up with people whose expertise complements yours. Do you see scope for increasing collaboration (including co-authored articles) between philosophers and other researchers?
Brit: Yes, I collaborate with psychologists and neuroscientists in various parts of the country and overseas (see here for the activities of my lab). That is very helpful, especially because we don't have all the equipment we need at our university. I like this form of cooperation. I have yet to meet a scientist who is not super-fast in terms of getting things done. Even when it comes to writing up the paper, they don't sit on it for weeks. Perhaps I have just been lucky but I suspect that the efficiency may also reflect that scientists are expected to publish a lot more than philosophers.
As for your last question, I feel that neuroscientists, in particular, are becoming increasingly interested in collaborating with philosophers. In several cases, it was them contacting me to ask if we could test something I had written about and not vice versa. There are still the occasional science snobs who thinks philosophy is a joke. But I think the attitude is changing for the better, and it's probably changing because our own attitude towards empirical data is changing. I like this new empirical turn. It definitely will make for much faster progress in both areas.