Is there a word or an expression for "Someone who looks for problems and is not interested in solving an issue pragmatically"?
In particular in my case I described a solution that was OK within the context given. Someone else presented a hypothetical situation: "If ... then it is not OK." Based on this hypothetical, they insisted that the solution I provided was not good. The hypothetical was an assumption, and it was completely unknown whether it would ever occur. My feeling is that this person merely wants to discredit my solution.
What do you call such a person?
I think this person wants to promote his/her own answer and is thus trying to find irrelevant "issues" with the answers of others.
But I would also be interested in the expression for someone who does it without bad motives.