Bill, I spent more than 10 years teaching college freshmen "critical thinking" in the context of a general liberal arts program. Naturally we never got into the heavy-duty Wittgenstein-Heidegger-Husserl stuff.
Lucky for me.

However, that experience convinced me that the natural tendency of the human mind is to believe what it wants to believe, until that belief is proved to be false.

For example:

Jill believes she can fly. She flaps her arms and gets nowhere. Jill realizes her belief was wrong.

Jack believes Sarah Palin would make a swell President. No disproof is readily available. So he keeps believing it.

A few years back I saw the world's most profound bumper sticker:

"Don't Believe Everything You Think."

Theory: The universal human tendency is never to examine one's own opinion. "If it weren't true, I wouldn't have thought it." Until adverse, external events prove someone's wrong, they'll keep on believing.

I'm not talking about maintaining your opinion after testing and examining it, as best you can, against alternatives. I'm talking about never examining it in the first place.