I started reading Nassim Taleb's extremely interesting book "Fooled By Randomness" last week and a line in the book caught my eye.
"Why don't most journalists end up figuring out that they know much less than they think they know?"
Trust me, this characterization of journalists' over confidence in themselves is right on. As an editorial writer for a local paper, I was once questioned why I had to quote Milton Friedman's famous line on inflation because he thought the truth of Friedman's statement (about inflation being a monetary phenomenon) is so elementary that it should be known by anyone without any training in economics! If it is indeed so elementary...then why economists like Friedman and Hayek had to fight so hard in alerting people about the inherent inflationary bias inherent in the then fashionable Keynesian economic policies?
1) Unlike journalist, a lot of people are really stupid. They cannot see the wisdom contained in the allegedly elementary proposition of Friedman's, so they have to be convinced many times before they can understand that excessive money causes inflation. A related question is: Are the smart people self-select to become journalists?
2) Journalists are just like everybody else. They just think they know more than they actually do as the line quoted above said.
Personally, I think no.2 is very likely to be the reality. And I believe that overconfience on the part of journalists, who think they are better than others, who think they are out there to change the world, is at least one of the major reasons leading to liberal bias in the media.