It seems like critical thinking isn't something that is taught, rather learned. I'm not joking when I say this; I've done this by accident many times before. A moment of clarity perhaps? It's hard to consider another point of view, but not impossible.

One way I think you can learn critical thinking, and this is what I'm doing is by doing critical reading. Dan Kurland has a website dedicated to the subject of critical reading. Anyway, if you can do that, I guess it's all about what you read. Hopefully you get a kind of proto critical thinking ability from that, and develop it through out your life.