How should a PhD student handle a retired professor who insists on continued collaboration despite declining research quality?

Question

I'm a math PhD student in my final year. A few years ago, a very well-known emeritus professor in my department offered to co-advise me. I initially accepted due to their strong reputation and past contributions to the field.

Over time, however, I realized that the professor is no longer able to contribute much mathematically. Most meetings involve general conversations or life advice, and on our two joint papers, I did all the mathematical work while they only edited the text. In another collaboration they invited me to join, the project seemed extremely elementary with no clear depth or direction, so I quietly withdrew.

Since then, the professor has continued to try to pull me back into that project, giving various justifications. While I respect their dedication and persistence to stay active after retirement, I feel it’s not productive for me. I'm now mostly working independently and have more defined research goals.

What's more concerning is that the professor seems unaware of these limitations. When papers are rejected, they often express frustration with referees rather than reflecting on the paper’s quality. It feels like they're seeking students not to mentor but to do the work for them.

While I respect their persistence to stay active, I worry this dynamic isn't good for students—especially younger ones who may feel pressured to say yes because of the professor’s name.

What’s the best way to respectfully disengage, and should departments be more proactive in setting expectations for emeritus faculty involvement with students?

Answer 1

Most of us don't go out with a bang but slowly and drawn over years. If we are lucky, all of us will age. It is always advisable to see the human beings behind the positions.

To your second question: absolutely. Departments should have a close eye on their oldest members, since there is no clear cut for retiring in academia. I experienced some very good "retired" professors and some who had visible signs of dementia. Unfortunately the former ones completely retired on their own before I graduated, while the other kind just kept going, even if barely any student showed up to lectures that where a tragicomic theater performance. This really reduced the quality of education. It was so bad that the department in the end had to step in, when it was too late for any graceful solution.

First question: this is still a professional setting. You should be respectful, but professional. Would you ask the same question, if the person wasn't past retirement age? How would you decline such a collaboration in this case? Would you directly say no or go an another route? Probably depends a lot on your academic culture.

If you have plausibly other stuff to do, this is a way out without being to direct, but doesn't solve the other problems.

Answer 2

First, see if there is a way for your primary advisor to serve as an intermediary. Perhaps they can "urge" the other person to pause, at least. They might also help with the following suggestion.

Your primary research is critical at the moment and you don't have time or energy (now) for side projects, even if you contributed to them in the past. Let the professor know this, suggesting that not is not the time for side projects and you have to work on the main line and will probably need to do so for a few years until you become established. If they accept that, then you can decide in the future whether to help out and how much time to devote to it. You will also have a position to work from that you don't now.