Why are people so ready to believe fearful things?

The amount of weird distrust and outpouring of hostility and violence at the town hall meetings on health care is amazing to me.

Why are people so much more ready to believe nonsensical concepts like “death committees” than the actual facts?

Is this related to conspiracy theories too?

Commentator Dave Ross has been attempting to apply reason, but reason does not seem to weigh with people at all.