Another factor encouraging us-vs-themism is a structural bias(?) that stems from our necessarily limited blogging resources. Borrowing from something Winston Smith at Philosoraptor ( philosoraptor.blogspot.com ) wrote a while back:

Given the universe of possible postings/news to react to, we’re most likely to write about what we find most outrageous. So if 100 events occurred, we agree on 98 of them, on the 99th “your team” was wronged, and on the 100th “my team” was wronged, you and I are likely to post about events #99 and #100 respectively, which highlights our differences and hides our agreements. (In fact, we may even agree on events 99 and 100, just not on their relative importance.)

I think the workaround is Friday Survey Blogging (find out where a blogger stands on the 99% of issues he didn’t post about) to replace Friday Cat Blogging, but we need someone with the requisite blogging authority to push it, in order to make it happen.