If your PhD student publishes 8 papers with you and you only then notice or claim that they cannot graduate that is an enormous failure in supervision and mentorship in every imaginable case. Either the student is really not fit to do a PhD, or their research is not worthy of a PhD or you are intentionally sabotaging the student. All those options indicate a serious failure on the side of the PhD supervisor.
> If your PhD student publishes 8 papers with you and you only then notice or claim that they cannot graduate that is an enormous failure in supervision and mentorship in every imaginable case
There are open questions nature of these publications. How many are first authorships by the student? Are they peer-reviewed?
> All those options indicate a serious failure on the side of the PhD supervisor.
I feel this potentially harsh. It's possible that the student just needs to get one or two papers past a peer-review process to satisfy the Prof.
I have to assume the facts stated in the post, I don't know if they're real or not. The facts stated there are that the PhD student has 8 publications, gave their thesis to their supervisor and that supervisor essentially shut down their PhD entirely. I am also assuming the publications are peer-reviewed, anything else would usually not be called a publication in this particular context.
This depends a lot on the field, but 8 publications is a lot. Which might mean there is more to this than told in the post, but almost all possible versions here still look bad for the supervisor. If the authorship is unearned the supervisor is just stuffing author lists which is unethical. If the student is not first author on any and their contributions are minimal, the supervisor failed to notice that the student hasn't been making progress for 4 years. In this case the supervisor might also have assigned the student to too many projects that are not PhD-relevant for this student. If there is at least one first authorship in there in a decent publication, that should be enough to justify a PhD thesis (not necessarily a good grade).
> If the authorship is unearned the supervisor is just stuffing author lists which is unethical.
Or the 2nd-3rd authorship is earned, but doesn't count enough as a scientific contribution to go into a thesis.
> If the student is not first author on any and their contributions are minimal, the supervisor failed to notice that the student hasn't been making progress for 4 years.
Or the student does have first authorships which have been submitted to a journal and put on the arXiv, but haven't been accepted yet so aren't enough for the thesis.
> If there is at least one first authorship in there in a decent publication, that should be enough to justify a PhD thesis (not necessarily a good grade).
Based on my experience (admittedly in the Netherlands, not Germany like in the OP), around three first authorships is the benchmark. But naturally there are variations between subjects/institutions/countries.
> How many are first authorships by the student? Are they peer-reviewed?
These are still supervision/mentorship failures. It is doubtful that the PhD student independently submitted papers to non-peer-reviwed venues without the Prof. having any say. And it is doubly doubtful that the student sneaked themselves as 3rd-4th authors in that many papers without the Prof. approving of that.
> It's possible that the student just needs to get one or two papers past a peer-review process to satisfy the Prof.
That is certainly possible. Still, having contributed to 8 papers over 4 years without enough of them qualifying as material for your thesis is bad supervision.
