Before people became so vocal and polarized about politics, there were some unsaid understandings between everybody. The kinds of implicit cultural values that make us think we live in a society. You may not care if your coworker votes Trump or Clinton, but you just assumed they believed in free speech, bodily autonomy, and the right to self-defense because it's America. Now Americans know that half the country is entirely at odds with the other half. We're surprised the "other side" doesn't agree with us because we just always assumed we had shared values. That and social media has poisoned the minds of a lot of people who never thought much about politics before.

And no you can't combat an idea with logic if someone didn't arrive at it through logic.