He finds it difficult to comprehend how the opposing point of view exists.
It's good vs. evil to Sorkin.
The problem is the republicans and democrats (who survive) will both commit to the beliefs which their polling instructs them to, so it really doesn't mean anything "real" to be a republican or a democrat. The parties evolve to cater to the beliefs of the mob they feed off. If the parties ignore evolution and stick to their manifesto if it's in conflict with their base, no mater how many months, years or decades old that manifesto is, they will fail.
In truth it's not good vs. evil, it's bland vs. bland.