The middle ground doesn't exist in itself. To have a middle ground you need to have a previous political position from which you can measure it, the illusion is believing that you can find a universal ideological space from which you can map the rest of ideological positions.

That is, when you take a certain political position that not only determines what measures you want to apply, it also determines how you see every other political position. The center is not the same center for a conservative and for a left-winger.