Image via WikipediaI read on Poynter.com that fark.com is not just for the Frat 'n Hooters crowd, so I go there, and I find a link to Roger Ebert, who I think of as a somewhat-overrated movie reviewer, and I follow that link to what he thinks of Bill O'Reilly and I find it thoughtful and persuasive.
What are TV shouters telling their viewers? They use such anger in expressing their opinions. Who are they trying to convince? They're preaching to the choir. Their viewers already agree with them. No minds are going to be changed. Why are they so mad? In a sense they're saying: You're right, but you're not right ENOUGH! I'm angrier about this than you are! Viewers may get the notion that there's unfinished business to be done, and it's up to them to do it.
He links to a summary of an Indiana University study that adds it all up.