では、なぜ北が上でなければならないのだろうか。 (From line 7: https://www.docdroid.net/847v2dg/img-20170413-0001-new.pdf.html) で should be a particle here right? If so, why is なければならない not attached to any verb? I don't know what this means.
I would say that the sentence means the following: "Well, why must the north be attached on top/in the upper section?" But I can't say why なければならない floats around freely like this.