The "obligation" to challenge stupidity that vjack speaks of is from a Christopher Hitchens quote that he posts on his blog and I've posted here in a slightly longer form,
"Never be a spectator of unfairness or stupidity. Seek out argument and disputation for their own sake; the grave will supply plenty of time for silence. Suspect your own motives, and all excuses ..."
As vjack says, if we always challenged stupid claims by others, we'd have scant time for anything else in our days. But that shouldn't dissuade us from doing so when we see fit. His query obviously comes from the atheist/skeptic community frame of reference, but it doesn't have to.
There are varying degrees of stupidity and for the criteria that determines whether one should respond. Does my challenging this specific point really make a difference? Am I being personally hurt by this person's stupidity? Is their stupidity willful or is just borne of a lack of knowledge?
Obviously, the definition of stupid is important. Stupid isn't merely someone who disagrees with us. I believe it means to be willfully ignorant. Knowing you are wrong but because of your prejudice or belief system, you close yourself off from fact.
That last item is where I get most upset. It's not that you don't know something. It's that you don't care ... those people that are not intellectually curious. Or it's that your worldview actively discourages you from seeking out answers. I have little problem with people that through having not been exposed to something before are ignorant. But I will challenge you to no end if you are content to stay in that state of ignorance. Being wrong is not a crime. Knowing you are and encouraging others to share in your delusions ... maybe that should be. This "willful" area, I believe, encompasses almost all religion.
"Faith is nothing more than the license religious people give themselves to keep believing when reasons fail." -- Sam Harris
Is it just being mean to call those of faith "stupid"? Maybe. Obviously "stupid" can't help but be taken pejoratively. But I'm trying to be serious here. I'm honestly trying to figure out why people believe certain ways and what keeps them from analyzing their own beliefs.
I can suffer a lot of ignorance daily, and mostly bear it well. While I don't consider myself an expert in my field (computers), I have quite a bit of experience, a pretty good memory and an ability to use the scientific method to troubleshoot issues. For these reasons, there are few things that I cannot solve. I don't always know the answer, but I'm not afraid to go out and find the answer.
"The hard but just rule is that if the ideas don’t work, you must throw them away. Don’t waste neurons on what doesn’t work. Devote those neurons to new ideas that better explain the data." -- Carl Sagan
In your fields of work, do you often feel compelled to challenge ignorance? Are you more prone to challenge it on non-work related issues? Are you more likely to challenge clients, strangers, co-workers, friends or family?
I try not to challenge clients ... for obvious reasons. What will it get me ... besides one less customer? But, there are a few areas while I will even challenge them, just to name a few: science denial, racism, sexism.
"What is it you most dislike? Stupidity, especially in its nastiest forms of racism and superstition." -- Christopher Hitchens, Hitch-22: A Memoir
What do you consider ignorance and how do you deal with it?