Essentialism

Philosophical essentialism is the idea that the nature of things is invariable and constant. Essentialism posits that one must be able to describe an entity according to that which is required, or essential, to its nature and existence.

The bird is perhaps a helpful example. One may ask what is essential to being a bird. Is it flying ability? No, flying is not essential to being a bird because there are certain birds that don’t fly (ostrich, emu, penguin, etc.). There are also non-bird creatures that fly (e.g., bats). A flying bird may experience an injury and not be able to fly anymore. Yet it is still a bird. If flying is not essential to being a bird, what is? Here are several aspects of being a bird that are essential: feathers, wings, a beak, no teeth, and bearing young in a hard-shelled egg. There may be other creatures that have one or more of these characteristics, but, for a bird, all of these are essential. If these characteristics are not present, then, whatever we have, it is not a bird.