What do you call a person whose interest might be to discredit your results by trying to find hypothetical mistakes? This person does not seem to focus on solving a problem with pragmatism. Is there a word or an expression for that?
I came up with an answer and the described solution seems valid. Most participants give good feedback, except this one particular person.
My feeling is that this person merely wants to discredit my solution/answer. I suspect that he/she does this in order to favor his/her own answer/solution.
P.S.: If possible I'd like to put it in a (most?) polite way. Let's say I am talking to the Queen of England and I want to tell that she ...
P.S.S.: Of course I am interested in other (formal, familiar, vulgar, etc.) words or expressions too. But let me know in which context it can be used appropriately.