[There is a principle which is a bar against all information, which is proof against all arguments, and which cannot fail to keep a man in everlasting ignorance—that principle is "contempt prior to investigation."]

I like what is written here and experience this a lot. I can relate this concept to another idea that the enemy of Love is indifference. People simply stop caring about the facts of issues that they decide are not important to them. Sometimes, in my opinion, they are choosing to stop caring because the situation/issue hurt them physically or emotionally and it is a protection/defense (such as hiding your head in the sand when you can't stomach learning about an illness or anything so bad you don't think you can handle - this is denial, keeping yourself in the dark on purpose or numbing yourself from feeling something about a person or condition of society.) other times the 'contempt prior to investigation' is the failure of a person to understand the difference between belief and rational arguments. Check out this position: http://sethgodin.typepad.com/seths_blog/
Don't argue about belief, argue about arguments
The essence of a belief is that we own it, regardless of what's happening around us. If you can be easily swayed by data, then it's not much of a belief.
On the other hand, the key to making a rational argument is that your assertions must befalsifiable.
"I believe A because of B and C." If someone can show you that "C" isn't actually true, then it's not okay to persist in arguing "A".
The statement, "All swans are white" is falsifiable, because if I can find even one black swan, we're done.
On the other hand, "The martians are about to take over our city with 2,000 flying saucers," is not, because there's nothing I can do or demonstrate that would satisfy the person who might respond, "well, they're just very well hidden, and they're waiting us out."
If belief in "A" is important to someone's story, people usually pile up a large number of arguments that are either not testable, or matters of opinion and taste. There's nothing wrong with believing "A", but it's counterproductive to engage with someone in a discussion about whether you're right or not. It's a belief, or an opinion, both of which are fine things to have, but it's not a logical conclusion or a coherent argument, because those require asserting something we can actually test.
The key question is, "is there something I can prove or demonstrate that would make you stop believing in 'A'?" If the honest answer is 'no', then we're not having an argument, are we?
Before we waste a lot of time arguing about something that appears to be a rational, logical conclusion, let's be sure we are both having the same sort of discussion.