What, you're saying that excluding the middle ground is a fallacy? By Jove, I think you may be onto something!
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.
The fallacy that there is a 'center' is just as bad as the fallacy of there only being a left and a right. Politics and economics are far more complicated than a continuum represented by a one dimensional line.