Try this out on a friend. Ask them these questions:
- On a scale of 1 to 7, rate how well you understand how a zip works.
- How does a zip work? Describe in as much detail as you can all the steps in a zip’s operation.
- Now, on the same 1 to 7 scale, rate your knowledge of how a zip works again.
They will almost certainly give a lower estimate the second time, becuase the task has revealed to them how little they actually understand about a zip. This is called the Illusion of Explanatory Depth. The truly terrifying thing is that we are all subject to this illusion, about all of our knowledge. None of us actually know a fraction of the stuff that we think we know.
The reason for this is that we confuse other people’s knowledge with our own. Because other people that we trust understand stuff, we think that we understand that stuff ourselves. We are all prey to this confusion, from A-level students (and teachers), to scientists, politicians, and “experts” of all kinds.
Sloman and Fernback argue that this is because our minds are equipped and optimised for thinking in groups, rather than individually.
The ideas in this book are related to the ideas of Tversky and Kahneman, which are outlined in Thinking Fast and Slow. Thinking Fast and Slow is a longer and more scientifically dense book, but The Knowledge Illusion is also a really fun read, and much shorter.