Matthew 18:20 (NET):


  For where two or three gather in my name, there am I with them.


There is so much technology now. 

Does the Catholic Church have a view on whether or not it has to be a literal physical gathering of two or more?


Question: When should a supervisor be a co-author?
Answer: well, that depends :)

For my own students I usually do not insist on being a coauthor. However, in most cases it just happens that one works together on a project which, by accident, is the thesis of one of the persons. In my experience, I had students who worked very much on their own and then they published their stuff alone. Perfectly fair to me. On the other hand, I had students which did not just ask some questions but we really worked together as I would do it with a collegue. So in this case, there was no question that we all are on the paper, sometimes even with a third person. In these cases, the student gets already some flavour of (partially international) collaborations which I believe to be worthy.

For a diploma student (that is a sort of master thing in Germany...) I'm happy if there is a good enough outcome leading to a little paper. Usually, these students are quite happy if they don't have to do it all by themselves.

For PhD students, I have the "rule" that there is a big global project for the thesis which is worked on, essentially in a collaboration. But I strongly encourage the students to tell me that there is some aspect, where s/he wants to work more alone and publish also alone. In fact, for a student aiming at a very good mark in the thesis, I almost expect that s/he has a paper published alone before the thesis is finished.

So, as I said, it depends very much on the situation. I think both ways have advantages and disadvantages. Important to me is that all involved persons feel good about the policy and that things are said in the beginning. Supervising students is always a matter of trust, and this aspect is certainly one of the most delicate ones...