The Diderot Effect - Why Do We Keep Buying Stuff We Don’t Need?

Updated on 1st January, 2023

The Diderot Effect Definition

With the rising popularity of Marie Kondo and her decluttering philosophy that we should remove items that do not spark joy, we find ourselves wondering how we ended up with all that clutter in the first place.

The answer lies in the Diderot Effect, a psychological phenomenon in which receiving or purchasing one item can quickly result in a snowball effect of consumption, where one purchase starts a chain reaction of more purchases. Okay, that sounds confusing, right?

Prisoner to purchasing because of the Diderot Effect
Prisoner to purchasing because of the Diderot Effect

Let’s think about it in real-life terms. A classic example is when people want to start working out. They buy a pair of shoes suitable for the gym, but none of their clothes match, so they buy a top to match, and then some trousers. Then they proceed to buy sweatbands and a new water bottle, Bluetooth headphones, and a yoga mat.

Do you see where we are going with this? They don’t need anything more than the gym shoes, a simple shirt, and a refillable plastic bottle which would do just fine, but they keep compulsively buying all these things to fill a void of necessity. This is the Diderot Effect at play.

What is the Diderot Effect?

It's no secret that we tend to always want more and are rarely completely satisfied with what we have. However, the Diderot Effect goes beyond this and can be thought of in two steps. The basic idea of step one is that the items we already have serve to connect our current identity, lifestyle, and self-expression.

Your favorite t-shirt, the coffee table in your lounge, and the plants you water and nourish are the essence of you. These items usually complement one another and align with whom we think we are. Human beings need these items to be a unit, existing in harmony with one another.

Research into the effect refers to these items as Diderot unities and suggests that we try to preserve these to protect our sense of self. This can also explain why we have a hard time letting things go, even if they no longer work or we don’t need them. Even if it's relatively useless and takes up space, an item might still fit with who we are, meaning we don’t want to let that go.

The psychological effect behind compulsive buying
The psychological effect behind compulsive buying

Step two happens when we introduce something new into the mix: a new outfit that doesn’t fit your usual style, a set of crockery that doesn’t match your other possessions, or a different piece of artwork. This can create a mismatch not just with our other things but with our sense of self, as it creates a new form of self-identity. We have two options here: get rid of the item that disrupts the connection between our possessions and identity, or buy more things that will correlate to our new identity. Most people choose the latter.

If someone buys you a new necklace, you might go out and buy earrings and rings to match. If you take up painting, you might start out with a canvas and some paints, but soon you’ll end up with fancy new sketchbooks all in different sizes, a special apron, and a new lamp for just the right kind of lighting. You’ve ended up with an entirely new set of Diderot unities to fit your new identity as an artist when all you really needed was a canvas and some paints.

Companies use the Diderot Effect to increase sales
Companies use the Diderot Effect to increase sales

At its core, the Diderot Effect is about the need for harmony between our sense of self and our external environment. But fear not, you can take action to overcome this effect. When you have the urge to buy something, it can be useful to remember that desire does not equal value. Consider whether there really is a need for your purchase or if you can use something you already own. Ask yourself whether this new purchase fits in with your other possessions to avoid the Diderot Effect tempting you to buy more. Lastly, a budget for maximum spending can help curb Diderot temptations if you stick to it.

It’s not all bad - Sometimes, the Diderot Effect can be a force of good. Don’t believe this? Take this example of sustainable living: someone may be inspired to buy an eco-friendly product, such as shoes made from recycled materials. This sparks an idea of a new identity for them as eco-warriors.

They notice that their other possessions are not so eco-friendly, so they buy green alternatives such as biodegradable cleaning products, refillable water bottles, or metal straws. Technically, they still don’t need any of these items, but doing something good for the environment can make us feel good about ourselves and helps our planet at the same time.

History of the Diderot Effect

The term Diderot Effect was coined by Canadian anthropologist Grant McCracken (1951-Present) in 1988. He studied the link between culture and consumer habits. According to McCracken, the reason we buy things isn’t always because they’re practical or functional. Seems obvious, right? But, in reality, the reason we buy things we don’t need is not so apparent. You might be wondering where the name of this effect comes from. While the name for this phenomenon came about in the late ’80s, the effects can be traced all the way back to the 18th century, to a French philosopher and writer called Denis Diderot (1713-1784), who wrote an essay in 1769 titled Regrets for my Old Dressing Gown: Or a Warning to those who have more taste than fortune.

So, some guy misses his old dressing gown. What’s that got to do with anything?

Diderot lived in poverty after being disowned by his father, who disapproved of his writing aspirations. He was the co-creator of the Encyclopédie, an encyclopedia that featured contributions from several secular thinkers of the time. The Encyclopédie was reviled for its atheist skepticism of the bible’s teachings and its arguments for secular thinking. It was banned by both the catholic church and the French government.

Diderot was so poor he could not afford his daughter's marriage dowery, and his possessions were incredibly old and humble. In 1766, Diderot’s fortune changed when the Russian empress Catherine the Great heard about Diderot’s financial woes and offered to buy his library and employ him as its librarian. She offered him a number of years’ salary in advance, giving him the wealth he had never had before.

In his essay, Diderot describes how a new scarlet dressing gown led to a frenzy of purchasing that landed him in debt and despair. At first, Diderot was delighted with his beautiful new dressing gown and got rid of his old one. But quickly, that delight turned to dissatisfaction as he noticed how run-down and old the rest of his possessions were in comparison. Before, they had complimented each other nicely and fit his lifestyle as a writer.

Now, this new dressing gown had upset the balance, and he had to replace the other items in his study: his straw chair, his wooden table, his rug from Bergamo, the wooden plank that held up his books, his art prints, and his tapestry. Each time he replaced one of these items, such as the straw chair, with a leather one, he would buy something new. The introduction of one nice dressing gown pulled Diderot into a chaotic spiral of compulsive purchasing.

It all started with an encyclopedia
It all started with an encyclopedia

Case Examples of the Diderot Effect

Case 1: It’s not just anthropologists like Grant McCracken and now you that know about the Diderot Effect. Marketers also know about it, and Grant McCracken has advised big brands such as IKEA about the powers of the Diderot Effect. Businesses use the Diderot Effect to boost their revenue and keep their customers coming back for more. They tap into our need for self-identity and sell it back to us. Let’s think about IKEA. The first clue is that IKEA displays and sells their furniture in sets, literal Diderot unities, allowing us to walk through them and imagine ourselves in our new kitchens, bedrooms, and studies. They know that if we purchase one item from the set, we’ll want to match it with the others, and they make it convenient and easy for us to do, so they do the hard work for us! But IKEA also sells lifestyles, when you walk through the different display rooms, you imagine yourself as all the different versions of yourself. Are you a homemaker? The studious type? Artistic? The design and layout of IKEA stores tempt us to purchase items that fit into that identity.

Sometimes, companies and stores will even add an extra step to purchasing to encourage the Diderot Effect. Apple no longer has a headphone jack in its iPhones or gives the adaptor plug for the new fast chargers when they sell a phone. Instead, users must purchase additional items to use their phones and are presented with the opportunity to buy many other accessories.

Russian empress Catherine the Great's large heart
Russian empress Catherine the Great's large heart

Case 2: The Diderot Effect can also be seen in cosmetic surgery. Ever been tempted to get Botox or lip fillers? It might be time to heed Diderot’s warning. People who get surgical enhancements are more likely to go back for more. You could say this might be a case of the fillers dissolving and needing a touch-up, but once people alter one part of their body, they usually start looking at what else they can change. The feeling of satisfaction after getting fillers tends to fade as you compare it with the rest of your features. You might be happy with your new lips, but what about your nose?

And so, the Diderot Effect begins as you make another appointment. In this case, once an individual has crossed the bridge into the cosmetic life, the second step they take is much less daunting, while the potential opportunities for physical change are exhaustive. Not only this, they have already undertaken one change on their body, so in their minds, it would be appropriate if they only change that and nothing else. As a result, the Diderot Effect takes over, and the drive to complete their newfound self-identity is ever so powerful.

The drive to complete newfound self-identity
The drive to complete newfound self-identity

Case 3: Still not convinced? Perhaps stepping into the virtual world might change your mind. Video games like Fortnite set the ideal background for the Diderot Effect to occur. Nobody needs a new outfit or “player skin” for a virtual character. Yet, the game offers multiple options to decorate them with all sorts of outfits. Often these avatars are meant to reflect a version of us, so people will purchase an item that feels either more like their real-life self or a self-identity they’d like to be.

That’s when the Diderot Effect comes in, as people realize that the other essential player accessories the game comes with don’t match the new item they bought, and they buy more and more. It comes down to a simple trick where marketers introduce a novel accessory with overlapping identity traits to your own as well as a whole collection of different traits, which opens you up to a new variety of items. That novel item acts as a sort of bridge towards a whole other terrain of potential purchases that prompts you to buy more as you feel you become more “complete.”

A Beautiful Quote

“Don’t find customers for your products, find products for your customers.”

- Seth Godin

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