Dunning-Kruger Effect – The Great Unknown

The Dunning-Kruger effect

Donald Rumsfeld, the U.S. Secretary of Defense from 2001 to 2006, will always be remembered for his expression of an old truism:

“… as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns — the ones we don’t know we don’t know. And if one looks throughout the history of our country and other free countries, it is the latter category that tend to be the difficult ones.”

The Dunning-Kruger EffectIn any field of human endeavor, there is a range of knowledge and competence that runs from the absolute beginner to the acknowledged expert. When starting, everyone is new, with a complement of known knowns that is, generally, empty. For example, when my friend wanted to start a small bookkeeping and accounting business, all she knew was that she was good with numbers. She always kept her family budget spotless and even helped friends organize their finances. Her knowledge was decent, but she really had no known knowns beyond her personal habits.

Given time, she started to develop a set of known unknowns. The questions started accumulating and her to-do list for learning grew at an alarming pace. As she learned more, she started shifting items from the second category (the known unknowns) into the first category (the known knowns, or her knowledge base). Her second category grew at a slower pace as she learned more, but it still grew. Eventually, her first category was larger than her second, and she felt that she had a decent grounding in the field of accounting and running a small business.

She was wrong.

The Dunning–Kruger effect

There is a fascinating study from 1999 by David Dunning and Justin Kruger of the Department of Psychology at Cornell University. In a nutshell, the Dunning-Kruger effect happens when someone thinks their competence in a skill or knowledge set is high simply because they don’t have the knowledge to know just how much they don’t know.

As a result, incompetent (or simply poorly skilled) individuals tend to overestimate their skill level, whereas skilled individuals are aware of their limitations.

These limitations are Rumsfeld’s “unknown unknowns.”

At the point where my friend thought she was starting to wrap her brain around running her own small business, she had a set of unknown unknowns that was much larger than she could have ever imagined, all of them hidden. She thought she was doing pretty well until one day someone asked her if she had ever done accounting for a nonprofit. She quickly realized that there was a whole new area she hadn’t considered. She now had a huge known unknown and months of learning ahead of her.

Was she a victim of the Dunning-Kruger effect? Likely so. If someone had asked her if she knew about bookkeeping and finances, she probably would have replied yes and been proud of the knowledge she had acquired, having no idea just how much she didn’t know.

The taxonomy of breadth

Category name What it is
(1) Known Knowns Your depth of knowledge. Everything you know that makes up your primary skill set.
(2) Known Unknowns Your breadth of knowledge. Everything that you know exists and some basic information about those things, but nothing more.
(3) Unknown Unknowns Your ignorance.


Based on this realization, I’ve come to classify people and behaviors based on which set is their primary focus (whether they realize it or not).

The Dunning Kruger Effect

Those who typically live in the third category, often without realizing it, have a huge complement of unknown unknowns. To be clear, these are people who have this huge complement and don’t realize it. They may think that their focus is on the first category, but the third is actually the focus. These people are living the Dunning-Kruger effect. They believe they know the sum and total of a subject and often find that things simply don’t work out the way they expect they should.

These people are surprised when events don’t unfold in the most obvious way.

Those who typically focus on the first category are the second-tier experts in any field. They have a large set of knowledge and can usually accomplish any reasonable task that requires that skill set, but they’re rarely innovators. They may realize that the third category exists, but they don’t put much thought towards that fact. They have their skill set and they’re comfortable with it. They will learn new things only as needs arise.

These people make excellent engineers as you can give them a task and they can immediately apply their skill and knowledge to complete the task. You can rely on these people to almost always demonstrate competence, but not always insight.

The true experts, however, are the people who typically focus on the second category — known unknowns.

They have, by necessity, a huge first set of known knowns because they consistently replenish their second category from the third. This person is the senior architect who can not only bang out the engineering task with her skills, but also knows the “lay of the land” from her breadth of knowledge. She might not know how to use all of the technologies available to solve a particular problem, but in having the breadth of all technologies in her known unknowns, she knows what’s available.

She can evaluate a problem against possible solutions, even those in which she isn’t currently conversant, and select the best or most likely one. Then, if need be, she can put in the time to move that skill from the second category to the first. If the decision doesn’t work, she has the breadth to realize this fact and make a course correction from other available options.

People who focus on the second category are constantly trying to find items in their unknown unknowns and get them into their known unknowns as quickly as possible. And in doing so, they acknowledge that their third category will never be empty, and they will never presume it is.

They avoid the Dunning-Kruger effect by simply realizing it exists.

These are the people you see reading industry trade magazines and websites, picking up an introductory book on the latest technology just to get a quick grounding, and always asking, “What’s new? What are you working on? What’s cool that I’ve not heard of yet?” And when they mention that they’d heard of the cool technology years ago, you mutter under your breath that they’re a hipster and just showing off. But that’s a different article entirely.