You missed the keyword -- "enlightened". You might not agree, but what you demonstrate is very common among new PhD students (and I would argue that is a desir

You missed the keyword -- "enlightened". You might not agree, but what you demonstrate is very common among new PhD students (and I would argue that is a desirable trait). I sure had that in my days of yore. Just clarifying that by 'impossible' I meant a mathematical impossibility theorem, not some notion of "that seems very implausible". Mathematical science does not progress by making impossible statements possible. Rather they work by scoping out and relaxing things (conditions, assumptions and axioms). For example, one does not deal with Russel's paradox by removing the paradox, but by scoping things out (in this case putting restrictions on how you define your sets) so that the paradox does not arise in the restricted, yet practically useful setting. OTOH other hand if someone keeps bringing up 'whoa Russel's paradox, whoa Russel's paradox that's a limitation' (albeit a well known and obvious one) that qualifies as newbie behavior, although an enlightened one. Inference in an arbitrary graphical model is NP hard. It would be lazy to come up with a corner case where a inference algorithm with a short running time will fail. We make progress by accepting that for arbitrary graphs inference is a hard problem and then asking what is a practically relevant subset of graphs where one can indeed give an efficient solution. Pointing out obvious failure cases is exactly what you said -- a [lazy and vapid] pissing contest. It does no one any good, unless the failure case brought up is of a new and an unknown type that provides new insight. If there was any new insight in the cases you brought up I definitely missed them.