The resilience of ignorance

In my social circle are a number of folks who use "alternative" medicine. A woman my wife went to college with puts homeopathic belladonna in her son's orange juice when he gets a cold, and is convinced that this cures him (belladonna is also known as "deadly nightshade" and was used as a poison in the Middle Ages). As she said, "Fight fire with fire." What does that mean?! The first time she told me this I was mortified, until I realized that she couldn't possibly be treating him with real belladonna, but was treating him with what is, essentially, water (homeopathic "medicines" are diluted so completely that they don't contain any of the original ingredients).

How is it that I can take the time to explain to her that it is just water, that I can explain about how her son would likely have gotten better at the same speed regardless of treatment, and that after spending 20 minutes at it, she is still convinced I am dead wrong?

"Nobody will ever listen to an explanation of why intuitions can be flawed - presumably because their intuitions have told them not to."

I've suspected for a long time that man is not a rational animal. But now, I have data. If anyone has ever wondered why irrational beliefs are so widespread, and so resilient, you should read this post at Ben Goldacre's badscience. Really, go read it. Now. Link to it. Send it to your friends. They really should know that:

"Our intuitions about the most basic observation of all, from which all others follow – our abilities to distinguish an actual pattern, from mere random background noise – are deeply, deeply flawed."

After reading his post, I'm not sure if I'm depressed or relieved...