Essentialismis the view that every entity has a set of attributes that are necessary to its identity and function. In early Western thought Plato's idealism held that all things have such an "essence," an "Idea" or "Form". Likewise, in Categories Aristotle proposed that all objects have a substance that, as George Lakoff put it "... make the thing what it is, and without which it would be not that kind of thing". The contrary view, non-essentialism, denies the need to posit such an "essence'".
Essentialism has been controversial from its beginning. Plato's Socrates already questions the notion by suggesting, in the Parmenides, that if we accept the idea every beautiful thing or just action partakes of an essence in order to be beautiful or just, then we must also accept the "existence of separate essences for hair, mud, and dirt". In biology and other natural sciences, essentialism provided the rationale for taxonomy at least until the time of Charles Darwin; the role and importance of essentialism in biology is still a matter of debate. In gender studies the essentialist idea that men and women are fundamentally different continues to be a matter of contention.