Sahil Bloom’s essay on June 26, 2026, “The Zipper Test: How to Stop Fooling Yourself” is about our understanding of everyday things. How many of us can explain how a zipper works, for example?

When asked to what level they understand the workings of some everyday thing, people rate themselves high. After attempting to write an explanation for how something works, they rate themselves much lower. The conclusion of the research is called The Illusion of Explanatory Depth:

…we are overconfident in our understanding of the most common things that exist all around us.

Sahil’s application is:

How much do we really understand about the most basic motivations, structures, and decisions that control our everyday actions, behaviors, and life path?

Without confronting this internal Illusion of Explanatory Depth, you leave yourself exposed to a life by default. A life where all of your motivations and actions are subtly adopted through a sort of cultural and environmental osmosis.

You may climb one mountain for 40 years, only to reach the top and realize you never wanted to be on it in the first place.

That’s a good application, but here’s another. I don’t NEED to know how a zipper works to use it. I don’t NEED to know how an internal combustion engine works to drive a car. I don’t NEED to know all the technical theology about the atonement (and people debate about that sort of thing all the time) to experience its results.

One thing I know: that though I was blind, now I see. – The man born blind, John 9.25, NKJV

In Him we have redemption through His blood, the forgiveness of sins, according to the riches of His grace… (Ephesians 1.7, NKJV)