> 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

> 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.