A fascinating new study conducted by Aczel Balazs, a professor at the Institute of Psychology at Eotvos Lorand University in Budapest, reveals that, no matter their backgrounds, most people completely agree on what is and isn’t stupid:

For each story, [test subjects] answered a range of questions, which included ones like “Would you describe this particular action as stupid?” and, if the answer was yes, “On a scale from one to ten, how stupid was it?” The participants were also asked to explain why they thought any given action was stupid, by choosing one of many categories.

What they found is that people tend to agree about what deserves to be called stupid and what doesn’t — remarkably, there was a roughly 90 percent rate of agreement.

The thing people agreed on as the most stupid behavior involved a misperception of self—“confident ignorance”:

Think of a drunk driver, who wrongly believes he or she is perfectly capable of manning the wheel. Or a burglar, who, meaning to steal a phone, instead plucks a GPS device, which leads the police straight to him.

People don’t just find this type of behavior stupid — they seem to associate it with the highest level of stupidity. These were given a mean stupidity score of 8.5 out of 10, a good deal higher than that for any other.

“The stupidest thing someone can do is overestimate themselves,” [Balazs] said. “What that tells us is that you don’t have to have a low IQ, in people’s eyes, to act stupidly. You just have to misperceive your abilities.”

I would add to that slightly. You have to misperceive your abilities and take great risks predicated on those abilities. It’s fine if you think you’re the world’s greatest tight-rope walker as long as you keep failing a foot off the ground. It’s another thing entirely to attempt a walk between skyscrapers. In the case of the drunk driver and the thief, they are taking enormous risks based on a misperception of their abilities. And apparently, according to everyone everywhere, that’s the most stupid thing ever.