Mereological essentialism

Mereological essentialism is a big phrase that refers to the idea that everything is made up of parts, and those parts are necessary for that thing to exist.

Let's say you have a toy airplane. Mereological essentialism says that if you take away even one part of that airplane, it wouldn't be able to fly or even exist as a toy airplane anymore.

Think of it like building with Legos. You can build a tower out of different colored Legos, but if you take away even one piece, the tower might not stand up anymore. Without all the parts, the tower wouldn't be the same thing as before.

This idea can be applied to people, animals, plants, and even inanimate objects. Each thing has its own parts, and these parts are necessary for that thing to be what it is.

So, to sum it up, mereological essentialism is the concept that everything is made up of parts, and those parts are essential for that thing to exist in its current form.