The Diderot Effect: Why We Want Things We Don’t Need — And What to Do About It

James Clear
Apr 17, 2018 · 6 min read
Denis Diderot as depicted by Louis-Michel van Loo in 1767. In this painting Diderot is wearing a robe similar to the one that prompted his famous essay on the Diderot Effect.

The Diderot Effect

Diderot’s scarlet robe was beautiful. So beautiful, in fact, that he immediately noticed how out of place it seemed when surrounded by the rest of his common possessions. In his words, there was “no more coordination, no more unity, no more beauty” between his robe and the rest of his items. The philosopher soon felt the urge to buy some new things to match the beauty of his robe.[3]

Why We Want Things We Don’t Need

Like many others, I have fallen victim to the Diderot Effect. I recently bought a new car and I ended up purchasing all sorts of additional things to go inside it. I bought a tire pressure gauge, a car charger for my cell phone, an extra umbrella, a first aid kit, a pocket knife, a flashlight, emergency blankets, and even a seatbelt cutting tool.

  • You buy a CrossFit membership and soon you’re paying for foam rollers, knee sleeves, wrist wraps, and paleo meal plans.
  • You buy your kid an American Girl doll and find yourself purchasing more accessories than you ever knew existed for dolls.
  • You buy a new couch and suddenly you’re questioning the layout of your entire living room. Those chairs? That coffee table? That rug? They all gotta go.

Mastering the Diderot Effect

The Diderot Effect tells us that your life is only going to have more things fighting to get in it, so you need to to understand how to curate, eliminate, and focus on the things that matter.

How to Overcome the Consumption Tendency

Our natural tendency is to consume more, not less. Given this tendency, I believe that taking active steps to reduce the flow of unquestioned consumption makes our lives better.



  1. Diderot’s scarlet robe is frequently described as a gift from a friend. However, I could find no original source claiming it was a gift nor any mention of the friend who supplied the robe. If you happen to know any historians specializing in robe acquisitions, feel free to point them my way so we can clarify the mystery of the source of Diderot’s famous scarlet robe.
  2. The quotes from Denis Diderot in this article come from his essay, “Regrets for my Old Dressing Gown.”
  3. Some readers have pointed out that my purchases were smart, not unnecessary. This might be true, but it is still an example of the Diderot Effect. Just to clarify: The Diderot Effect simply means that when we obtain a new item when tend to acquire additional ones. It’s not a value judgment that only applies to unnecessary purchases. So, even if my purchases were smart, I still feel victim to buying more things once I made an initial purchase. Of course, the Diderot Effect often results in unnecessary purchases, which is why I focused on that angle in this article.
  4. The Overspent American: Why We Want What We Don’t Need” by Juliet Schor. Chapter 6.
  5. Thanks to my friend Joshua Becker for originally sparking my interest in the Diderot Effect by writing his own article on the topic.

Personal Growth

Sharing our ideas and experiences.

James Clear

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I’m the author of Atomic Habits: atomichabits.com. I write about habits, decision making, and continuous improvement.

Personal Growth

Sharing our ideas and experiences.