My favorite page on WIkipedia is the List of cognitive biases, which I consider fundamental reading material for human life. Yesterday I talked about the Dunning-Kruger effect. Today I want to talk about Essentialism, which is the perspective that particular kinds of things, like chairs or boats or groups of people, all share a fundamental set of qualities, that they have an "essence."
In the first sentence of the Essentialism page on Wikipedia, it's identified as a philosophical term, which is why I love that it's linked from the list of cognitive biases. It's a philosophical view that's been woven through the traditions of Western thought, and is deeply embedded, not just in the way we naturally see the world, but in the cultural conventions of truth that Westerners grow up surrounded by.
Essentialism says that everything can be organized into discrete, clear categories. This may be true on a submolecular level (to my knowledge, all top quarks are unambiguously identical) but it's not true on the level of people and stuff, which is the level at which people like to try and apply it.
For example, racism and sexism are both essentialist in nature. The perspective that everyone who has particular qualities must therefore be deviations from an archetypal individual, the stereotype of that group, is essentialist.
The reasons that this is a flawed perspective should be obvious. For any given category, either you have to make tautological claims, appealing to the thing's definition, like "All lawyers practice law," which will almost always hold true but still occasionally fail (does a retired lawyer cease to be a lawyer? What do you call someone who's passed the bar, is recognized by the state as a lawyer, but never works on any cases?) or you have to try and hang other characteristics on the stereotype, like "All lawyers are dishonest," which is just going to turn out being wrong even more often.
There's a difference between essentialism and abstraction, and it's important. Fields like sociology or statistics (or writing) rely on the ability to generalize about groups. But most people, in close to every aspect of their lives, make these generalizations automatically, without noticing, and then hold them as facts of the nature of the world, rather than incidental qualities of their circumstances.
The opposite of essential is incidental, and it's generally safer and more correct to assume that all the qualities about a thing are incidental than that there's some essential form out of which all versions of a thing come.