Let's start with stupididity.
Here in Germany, homeopathy is a multi-billion Euro industry. It was invented here, so perhaps that's why even insurance will often pay for it (although not as much as it once did). It is a ridiculous and stupid concept, basically operating in the same way as this true anecdote:
When I was in college, I bartended over the summer. (My Ivy even offered a non-credit Mixology class). The first time I made a martini for a real alcoholic, she sent it back: not dry enough. I dumped it and re-made it but I still used the same ice cubes and it was still "too wet". My manager re-made it, with a different shaker and new ice and I noted that she did not add any vermouth at all. She told me the old joke:"When making an extra-dry vodka martini, you just whisper "vermouth" three times over the ice." What the drinker wanted was chilled straight vodka and the belief that she was having "a mixed drink" rather than drinking the equivalent of the purest alcohol one can buy in New York.
That's homeopathy. You dilute an ingredient that may or may not be useful beyond any recognition beside existing in the same world, package it prettily in a sugar pill and container and prescribe it. It may actually succeed in doing something for an ignorant patient, due to the placebo effect.
I am actually good with giving stupid people sugar pills (it only works on those who believe in it) and hoping that it makes them better, my problem is with the disgusting profits made by the industry and paid in many cases by governmental insurance companies, as well as the people who actually make careers out of being "homeopaths" and waste their lives going to "homeopath colleges". They would be far better off taking a course in massage therapy and throwing in the homeopathy for free. By the way, I am not knocking herbal remedies here: those are actual, although perhaps dangerously uncontrolled, remedies.
Moving on to the type of stupidity that damages others in a terrible, perhaps life threatening way: not vaccinating children.
The German and I were at a convention in London last year that actually offered babysitting. We hadn't known that when we registered and that was actually the first weekend that we ever left the kids with the grandparents. When we arrived and saw the service, we were kicking ourselves for being separated from the kids. That is, until we saw next day in the convention newsletter that a child in babysitting had the measles and had exposed everyone there (as well as whoever else had come into contact with the children).
While standing in line for something the following day, we wound up discussing this behind the very parents who were responsible for their child exposing a swathe of perhaps extremely vulnerable (especially younger- babysitting went down to 12 months!) people to this quite dangerous disease. As we discussed how grateful we were that our kids weren't there, they turned around to tell us how terrible this was for them, how they had to take their kids to the grandparents (they were London residents!), how it had interfered with their lives.... I was apalled. This is becoming increasingly common in the UK and Europe. Europe is now exporting measles cases to the Third World. Measles is not a common cold. It caused 530,000 deaths in 2003. It is wrong and selfish and stupid for mis-educated, ignorant parents in the First world, who rely on a good system of health care and well nourished children to allow their children to survive to put the rest of the world at risk of death and birth defects.
I am not saying that I don't have serious concerns about giving too many vaccines at once, or about when there was thimerosal (to which I am violently allergic) in them (thimerosol is no longer in childhood vaccines and I make certain to check that they aren't old vaccines).
There are currently vaccines that are different in different areas of the world. When we arrived in Germany, I made certain that my children received the meningococcal vaccine that is not given in the US. But when they were born, I delayed the hep B until they were a month old because I didn't feel it was necessary that they have it at birth. I have pushed vaccinations when they were ill, I have split them and used only vaccines without thimerosal. But I would never dream of allowing my kids to be susceptible to terrible diseases and to destroy the herd immunity
which is all that protects the prgnant and immune suppressed and old and ill from a terrible death.
That's just plain stupid and I think the healthy non-immunized should not be allowed to co-exist and reap the benefits while destroying them. No schools (which is illegal and therefore would mandate immunization in the school age), no pubic venues, no public babysitting: live in enclaves until you can show a blood titer. Do you have better answers?