Elephant in the living room
The elephant in the living room, or just plain elephant in the room, is the glaringly obvious fact that no one is talking about. It shares a similar place in discourse as the emperor's new clothes, in that the iconoclastic critic can try to make a strong point without getting mired in the details of other people's arguments.
This can have great value, of course, as in both situations, there are times when public discourse over an issue ignores the obvious (or has no clothes).
One example of an elephant in the living room situation is the current "discussion" of health care availability in the United States, where most discursants address the problem by trying to tinker with the current system, while ignoring that the profit motive that drives corporate capitalism is completely at odds with the goal of a health care system.
The argument also tends to attract nutjobs, though, since they can ignore existing agreed-upon realities and gleefully announce their pet ideas as being the "real" paradigm.
This should not be confused with an actual elephant in the living room, in which case you should check for emtpy liquor bottles before calling your local zoo.