We know politics makes us stupid, but now there's evidence (pdf) that politics makes us less likely to consider things from another's point of view. From the abstract:
Replicating prior research, we found that participants who were outside during winter overestimated the extent to which other people were bothered by cold (Study 1), and participants who ate salty snacks without water thought other people were overly bothered by thirst (Study 2). However, in both studies, this effect evaporated when participants believed that the other people under consideration held opposing political views from their own. Participants who judged these dissimilar others were unaffected by their own strong visceral-drive states, a finding that highlights the power of dissimilarity in social judgment. Dissimilarity may thus represent a boundary condition for embodied cognition and inhibit an empathic understanding of shared out-group pain.
As Will Wilkinson notes:
Got that? We overestimate the extent to which others feel what we're feeling, unless they're on another team.
Now this isn't necessarily a negative effect - you might argue that it's bias correcting. But implicitly viewing them as so different that it's not even worth thinking about things from their perspective is scary in itself.