Randy Barnett writes an interesting post over at GlennReynolds.com. I've noticed this behavior too, and I agree that it seems to be getting worse.
Take the 2000 Presidential Election, for example. I no longer attempt to discuss it with family or friends, because I do not expect to be able to have a reasonable discussion -- nor even to find meaningful facts both sides are willing to agree on.
As far as point (3) -- "how do I know I'm not doing the same thing in reverse" -- you don't, and you can't. There's no straightforward way to prove that you're not living in a self-generated reality distortion field. It is for this reason that turning the tables is the favorite counter-argument when someone challenges the claim that truth is socially constructed. I believe the jargon word in literary
criticism is privileging, as in, "You're just privileging your own narrative."
The only recourse I have found is to develop a brutal sense of intellectual honesty, watch for self-deception, and freely admit error. The last is the most important point, I think.
Someone I know well, whose politics are well to the left of mine, had an active episode of mental illness (approximately, a paranoid-type schizoaffective disorder) brought on by the recent Iraq battles. A characteristic of this kind of illness is the patient's total lack of doubt in his beliefs, and an unwillingness to admit even the possibility of error.
Sound familiar? Iraq was not a bloodbath nor a quagmire. Baghdad was not razed in house-by-house fighting. There are not millions, nor hundreds of thousands, nor even tens of thousands of refugees. These predictions of the anti-war camp all proved false. I have not seen them retracted.
On the other hand, I have seen a significant amount of writing on the subject of the missing chemical and biological weapons believed to be in Hussein's hands at the beginning of the war. It's certainly starting to look like Iraq had more WMD capabilities in the 80s than in the 90s or in 2003. It's not quite comparable with the intelligence failures regarding 9/11, because in this case we were incorrectly overestimating the enemy's strength, and the failure mode for that is less unpleasant. So there's something that the pro-war camp was wrong about. And I think that's been said.