All of us are capable of it. Indeed Chicago is the Mecca of Comedy. From Improv classes at Northwestern (include in that recent live sex ed demonstrations), to more comedy clubs than anywhere else in the world, Chicago breeds comedy, most based on incredible stupidity. Saturday we dyed the river green to begin a week of proper Irish drunkeness. I was in the Cuban Cafe "90 Mile" picking up carryout and there were three Chicago Cops trading stories from the Saturday night shift. "Eight hours later I got him out of holding and he was as drunk as when I put him in!" (reference any episode of "Shameless", Sundays 9pm, HBO)
Being intelligent and well informed does not exclude you. Admit it. We have all done stupid things, some we regret, some we remember fondly (I don't know how to categorize the squirt gun ambushes on drunken freshmen while tripping at Ohio State. Hey, it wasn't my Idea. Going along can be stupid too.)
So, let's review.
We know stupid people can act stupid (reference "Jackass the Movie"). Actually stupid people, though plentiful, don't act stupid all the time and most disguise it the best they can. The males usually try to cover it with excessive macho bluster which usually only works for females of the stupid persuasion (reference reality television, ok, and George W. Bush). OMG they're breeding!
Drunkeness can promp stupidness no matter what the IQ or usually sensible nature of the drunk. After all, stupor and stupid come from the same Latin root meaning numb. (long term drunkeness can make the stupid permanent with the side effect that they think their actually smart, reference Charlie Sheen, and yes, George W Bush, again)
Excessive multi-tasking can cause stupidity usually afflicting those who think they're smart, like the Northwestern student riding his bike down the yellow line on the busiest street in Evanston, his laptop open in the basket, his phone held to his ear, steering (poorly) with the hand holding his cigarette. I do hope he avoided that Darwin Award.
Then there's the world champion causes of stupidness. Love, dispair and desperation. I had this epiphany when I first saw "Raising Arizona" (and I'm loathe to admit this because I really don't like Nick Cage's work). But, our prisons are full of stupid, desperate people. Prisons aren't full of evil genuises and their talented henchmen like most movies would have you think.
All this leaves us to explain the stupidity of the rich white men who allowed this nation of manufacturing to devolve into what it has become.
Here are ideas that try to explain everying: