Let’s pick a topic. Any topic. How much would you say you know on that topic? More than average? How much do you think you need to learn in order to become well-versed on that topic? Not a whole lot? You just may be experiencing what is known as the Dunning-Kruger Effect. It is a mental bias that seems to afflict people who are unskilled or not very knowledgeable. They routinely make poor decisions because their lack of competence itself denies them the ability to realize their lack of competence. It happens to a lot of us in certain areas like personal financial planning.


This effect was discovered in the late nineties by David Dunning and his then graduate student Justin Kruger. Dunning explains it in the words of Donald Rumsfeld during a famous press conference describing conditions in Iraq right after the invasion (“…there are known unknowns and unknown unknowns”). The “unknown unknowns” are what Dunning thinks happens to people when they fail to realize that they don’t even know what questions should be raised, leave alone knowing the answer to those questions. This leads people with limited knowledge to overestimate their ability while, paradoxically, leading skilled people to underestimate their ability.

In the course of conducting our everyday life, it seems useful to at least think about the Dunning-Kruger Effect so we can start asking some questions that we did not even know existed. The answers may be difficult to come by, but asking the questions by itself seems like a significant step forward.

If you want interesting but not heavy reading on this topic, check out this interview with David Dunning.

My favorite Dunning quote from it is “One could argue that evolution suggests we’re not idiots, but I would say, “Well, no. Evolution just makes sure we’re not blithering idiots. But, we could be idiots in a lot of different ways and still make it through the day.””

David Dunning is a Professor of Psychology at Cornell University and Justin Kruger is an Associate Professor of Marketing in New York University.