IN THE COMMENTS: Diogenes of Sinope asks:
Do fish know they're wet? Do the media know their biases?I think they know and simultaneously do not know. If they stepped outside of the ongoing process of running their business, pursuing their careers, and they had something to gain by utter truthtelling, they would admit that they have a liberal bias. But that's not where they are, and they must keep going. I don't know these people, but I would guess that their day-to-day level of self-awareness — their working mindset — really is that they are doing the very same thing, applying a methodology to whatever raw material comes their way. If the end result looks different, it is only because the raw material was different.
Another way to put that is the familiar quip: Reality has a liberal bias.