It would be interesting to know just when this tendency started in our culture, but it goes something like this: if I am going to learn from someone, I must believe everything they believe. So often I hear remarks such as, "Yes, I agree with that, but..." and what follows is a distancing from the person who spoke the morsel of truth. For example, a politician may have a particularly insightful opinion on a specific subject, and many are afraid to admit they agree for fear of being mistaken for a supporter of said politician. Why can't we just learn what there is to learn, no matter its source?
I would be hard pressed to name a single politician, preacher, or pundit whose opinions I agree with 100%. That does not keep me from gleaning where I can. This is much of what critical thinking is: learning to chew the meat and spit out the bones. I would go as far as to say that it is possible to learn from those whom we generally consider our adversaries. Corrie ten Boom said our critics are the "unpaid guardians of our souls".
To use another analogy, I learned many years ago the principle of drinking from a diversity of "wells". If I drink from the same well continuously, I am more likely to have a skewed world view and an unbalanced perspective. Whether we're talking about news, business advice, teaching methods, or spiritual principals, it is important to absorb information from a variety of sources in order to have a well rounded perspective. Then we form our own opinions based on the information we've gathered.
Couldn't our culture benefit from a good dose of critical thinking, with a dash of humility?