The Diderot effect is a phenomenon that occurs when acquiring a new possession leads to a spiral of consumption that results in the acquisition of even more possessions. In other words, it means that buying something new can cause a chain reaction of buying more and more things, as the new item makes one feel like one needs other things to go with it or to keep up with it. This can lead to overspending and accumulating more possessions than one actually needs or uses. The term was coined by anthropologist and scholar of consumption patterns Grant McCracken in 1988, and is named after the French philosopher Denis Diderot (1713–1784), who first described the effect in an essay titled “Regrets for my Old Dressing Gown, or, A warning to those who have more taste than fortune”
The term has been used in discussions of sustainable consumption and green consumerism, in regard to the process whereby a purchase or gift creates dissatisfaction with existing possessions and environment, provoking a potentially spiralling pattern of consumption with negative environmental, psychological, and social impacts.