Co-advisors for a dissertation?

In our September "how can we help you?" thread, a reader writes:

I am a grad student and a faculty member suggested to me that I may want or need co-advisors for my dissertation given my department's faculty and the two intersecting areas I want to work in. I can imagine that this has both pros and cons. Can anyone offer any advice about this? Has anyone had co-advisors? If so, how did it go?

Interesting questions. I've never heard of co-advisors for dissertations before. One obvious potential benefit here is that you would have two people who are highly invested in the dissertation. However, the obvious potential con is that they may want fundamentally different things out of it. I didn't have co-advisors, but something like this happened to me. When I was doing my dissertation, my advisor thought that I should make the theory broader than just Rawlsian nonideal theory. However, one of my other committee members thought the dissertation should focus primarily on Rawls. Yet, precisely because the latter wasn't my supervisor, they deferred to my supervisor. What would have happened if they were both co-advisors? I can imagine it would have been a stickier situation. And I could imagine it could be an especially sticky situation if the co-advisors are in quite different areas. Here, I imagine it is important to think about the personalities of the potential co-advisors, and how well they might 'work together', as it were, in supervising a dissertation in common. Then again, this is really just me speculating. Anyone with any experience here able to weigh in?

Comments

[rutabagas]

I had co-chairs, and it worked great for me. It turned out that I gelled much more with one than the other, and grad school would've gone much worse for me if I'd only had the chair whose style wasn't a good fit for me--but that chair's feedback was tremendously valuable, and I would have had a worse dissertation without them.

For me, though, the thing that was absolutely critical was that the chairs knew each other well, were friends, had a sense of each other's strengths and weaknesses, and had co-chaired dissertations before. I would be very nervous about having co-chairs who didn't know how well they'd work together, for exactly the reasons Marcus gives.

[Michel]

Every student who came out of my PhD program had two supervisors. (A few had/have a third, but that's pretty rare.)

One is designated as the primary supervisor, the other as the secondary. Usually, they're from two different subfields represented by the dissertation project. Often, the primary just takes the lead, and the secondary chips in here and there, especially where you cross into their primary area(s) of expertise.

Direct conflicts are pretty rare, but there are different ways of addressing them. One is to defer to the relevant subject area expert, if it's a conflict about content. Another is to try to balance the conflicting takes, or to use your own judgement. It's not at all uncommon, however--or, it wasn't, when I was there--to simply tell both supervisors about the conflict, and ask for guidance through it.

[jed]

This is a good question; here are a few thoughts. One thing you might think about when considering having two supervisors is what their respective expectations will be for you as their student. Is one more hands-on, one more hands-off? Might you work better with one's supervision style as opposed to the other's? Having to manage two different sets of expectations might be unnecessarily onerous. Also, while writing a dissertation is a task ultimately for the student, the project will inevitably be shaped by the supervisor's guidance and input. Some supervisors might be more insistent on this score than others, and if you have two of them, their advice might sometimes come into conflict. I'd think a bit about how best you work, and what pace you work best at, the potential supervisors' advising styles, and whether they'd be a good fit.

As I write this, it seems this advice would go for any student choosing a supervisor, whether multiple or just the one, but the decision procedure strikes me as more complicated when there are two potential supervisors in play.

[Shay Logan]

I had two dissertation advisers. It seemed pretty straightforward to navigate. Like Michel said, if conflicts come up, just talk to them about it. In my experience, almost always it turned out that I'd misunderstood what one or both of my advisers was trying to say. In that sense, I found the disagreements Marcus seems to be worried about ended up being useful for me, as they taught me to notice various ways I was misunderstanding people.

[Overseas TT]

I did this and it worked out great. It spontaneously ended up being a kind of "good cop / bad cop" arrangement, where one of my co-advisors was much more critical of my work and forced me to anticipate a barrage of serious objections, while the other was generally more sympathetic to my views and helped me a lot in presenting them in their best form. Both of them were very helpful. They did often disagree with each other, but I never felt stuck or discouraged because of that (and, I should add, neither of them were difficult to work with if one disagreed with their views).

I should note, because I don't think this came up, that one potential pitfall of co-supervision is that one can fall between the chairs a little bit. This didn't happen to me (partly because I was somewhat proactive about it), but I know it happened to some fellow grad students. It's a good idea to be upfront at the beginning about how the responsibilities would get divided between the co-supervisors.

[Dissertation table.]

Dissertations being co-chaired was the default practice where I went to graduate school. My experience was good, for many of the reasons mentioned above. In my case, there wasn't too much worry about 'falling between the chairs', because it was almost as though I was working on a dissertation independently with each of my chairs. They'd encourage me to seek out the advice of my other chair, but it was never the case that one chair would say they were unable to read a given chapter and that I should send it to the other chair.

One thing that was shocking, though entirely predictable, was how difficult it was to get the three of us together in one room once a year as was required by the graduate director.

[Remco Heesen]

As someone who has moved to Australia somewhat recently but did not do my PhD here, my understanding is that co-supervision is the norm here. Everyone here has two supervisors, or so I'm told. They're assigned percentages which are typically unequal, leading to a primary/secondary advisor kind of thing, much like Michel describes.

[pd]

I had co-supervisors. It worked well. I don't recall any conflicts. It probably helped that they were friends and neither was insistent on much. I'd guess the main benefits were more feedback and more investment in what happens to me on the market.

Other thoughts:
- The supervisor that's best at supervising may not be the supervisor that's best from a market perspective. Having co-supervisors can be a way to get both.
- Having co-supervisors can bear on which letters you can or should use for job applications. E.g. when supervisor letters are required and there's a max for how many letters you can submit, having co-supervisors may in effect require you to drop an external or teaching letter. I suspect this is at most a minor consideration that could easily be outweighed by other factors, but I'm not confident in that assessment

[Prof L]

My dissertation was co-supervised and it worked great. So just a +1 to what everyone else is saying. Obviously a lot depends on the supervisors and the student, but that’s always true. If there’s a good reason to do it, and no foreseeable major conflicts or personality issues, do it!