There's a psychological concept known as the Halo Effect in which an object, person, or ideology (OPI) in which you find positive is assumed to have no negatives and an OPI in which you find negative is assumed to have no positives. This effect can be illustrated through some very simple thought processes:
- I like Jill, she is nice.
- I think donating to charity is nice.
- Therefore, I assume that Jill donates to charity.
This assumption is based on no outside information. I have never spoken to the hypothetical character named Jill, but I have a predisposition to assume that Jill would be "the kind of person who would" donate to charity. If we step back and think, we would realize the fallacy here, but until we actively engage in that thought processes, or until we receive information which contradicts this (e.g. "Jill is especially tight fisted with her finances"), we will operate on the assumption that Jill donates to charity as if it were a fact.
This assumption of fact is more powerful than just the Halo Effect. When we receive information, we immediately categorize it into one of two different sets: True and False. As a result, it's increasingly difficult to reach informed, unbiased positions with simple things (crop yield statistics), and almost impossible with complex issues. When news agencies lost their journalistic integrity, they helped set the stage for the polarization of the American public.