The existential quantifier ∃ is often used in logic to express existence. Existence is the state of having being or reality in contrast to nonexistence and nonbeing. Existence is often contrasted with essence: the essence of an entity is its essential features or qualities, which can be understood even if one does not know whether the entity exists. Ontology is the philosophical discipline studyin
![Existence - Wikipedia](https://cdn-ak-scissors.b.st-hatena.com/image/square/dfee0e25c3b1029e3ca31353b38233e81204551e/height=288;version=1;width=512/https%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2F2%2F28%2FExistential_quantifier.svg%2F1200px-Existential_quantifier.svg.png)