PhD: When to quit and move on? I am a second year PhD student at a technical / interdisciplinary lab in Europe wondering when to quit and leave a seemingly unbearable situation behind.

My supervisor (a young-ish professor) mostly works alongside an older professor (his own PhD supervisor back in the day). I am one of his first "own" PhD students. The project that pays my salary is a joint project with another group with a focus lying outside my supervisor's main interests (so he also doesn't care too much about it).

I have mostly spent my time working on ideas suggested by the old professor. Every time he makes a suggestion for something I should work on, I look into it until my supervisor says the results are good. Then we meet with the old professor who basically says the work is ridiculous. At this point in the meeting my supervisor agrees with the old professor and they tell me to do something else. This has happened maybe 6-8 times in the last 1.5 years and all my work has been scrapped.

My supervisor, on the other hand, spends most of his time providing supervision to the old professor's PhD students, pushing them to make the most out of their research (ideas given by the old professor). The result is that they publish really nice papers (and he is of course a co-author). I on the other hand don't really have something going on, and my colleagues really let me know that my PhD is going nowhere (instead of providing encouragement or responding to offers of collaboration from my side).

I know that getting a PhD means being able to conduct research independently and I am trying to get there. I have had a number of ideas for research but when I suggest something to my supervisor he doesn't really care about the topics. All the old professor's students work together on everything but I am pretty much isolated. This makes it really hard to learn what I need to learn and to achieve something I would consider publishable. Most ideas that I try out for a few days / weeks or longer lead nowhere. I think one reason for this is the lack of feedback or helpful ideas etc. that I would expect from my supervisor and/or colleagues which I simply do not get.

One good example for how things are going is the paper that grew out of my MSc thesis. It has been more than 1.5 years and we are still in the process of "making it ready for publication". We meet every few weeks and the old professor (who is a coauthor) demands substantial changes (often reversing decisions that he himself made some meetings ago). My supervisor doesn't really seem to mind that this paper doesn't get published (in the meantime they have put in lots of effort to publish a number of papers with the old professor's students at top conferences and journals).

Overall this situation is obviously very frustrating, up to the point where I have set myself multiple deadlines until which things need to have improved or otherwise I start looking for another position. But I haven't.

I do some teaching which I really enjoy. This is my main (actually only) source of positive feedback (from the students) and as such really motivating. As I have taken up these and other duties at the lab I am under the impression that I am to some extent indispensable for my supervisor as I do lots of valuable work for him (work that he doesn't have to worry about). Therefore I think that no matter what happens he will at some point make sure I get my degree. As the situation currently seems, though, I will have a sub-average research record at best which will make any academic career impossible.

Sorry for the long text. My question is: how bad must the situation look before it is advisable to quit and move on? I am not a quitter and would hate doing so but my personal life and mental health have been suffering to the point where I find the situation unbearable.



Note that there is no such thing as a thesis committee at my university. Everything depends exclusively on the PhD supervisor.
This can really only be answered by you. But here are some thoughts. 

There are two doors. One leads to a doctorate and the other does not. If there is no path to the first door, then the decision should be clear. But there are a couple of possible paths to that first door. 

One is to move elsewhere or get a different advisor. If that path isn't closed to you then you should be considering it. Expensive and time consuming, yes. But whether it is worth it is up to you. 

Another, possible, path is to cut the old prof out of the picture and work exclusively with the younger one on some idea and just finalize it without consulting the older prof. 

A third, is to cut out the younger prof and work exclusively with the older one and his group, perhaps getting some support from them and hopefully more from the old professor. 

But it seems like you are being whipsawed. Find a path that works. Even if it is to the 'no degree' door. But make sure that you will like what is on the other side of that door before stepping through it. 

My personal preference (maybe not yours) would be to work with only the younger prof. But get a plan agreeable to both of you that if you follow that path you will find success in a reasonable amount of time. I mean, preferably, a written plan, or at least one that clearly lays out the parameters. 

If you don't have a plan, you probably don't have a path. 



My situation was a bit different, though also difficult, but I switched universities after four years in grad school and found a much better situation and an excellent and helpful advisor. My future seemed bleak at the time, but it was with the encouragement and help of another professor that got me situated.