Existence

Existence is the state of having being or reality. It stands in direct contrast to nonexistence or nonbeing. Philosophers study the nature and types of existence through a discipline called ontology. Ontology is a subdiscipline of metaphysics. It examines the most fundamental features of reality. The concept of existence separates real entities from imaginary ones. It can refer to a single object or the totality of all reality.

To understand existence, thinkers often contrast it with essence. Essence refers to the intrinsic nature or defining qualities of an entity. It describes what an entity is. Existence describes the fact that the entity is. You can understand the essence of an object without knowing if it exists. For example, you can grasp the nature of a dragon. However, a dragon does not have existence in the real world. Martin Heidegger (1889–1976) explored this through the ontological difference. He distinguished between individual beings and the concept of being itself.

Philosophers categorize existence in several ways. One major distinction is between singular and general existence. Singular existence refers to individual entities. For example, saying "Angela Merkel exists" is an expression of singular existence. General existence pertains to concepts, properties, or universals. Saying "politicians exist" refers to the general term rather than one person. Gottlob Frege (1848–1925) argued that general existence is more basic. He believed singular existence could be expressed through general terms. Conversely, Willard Van Orman Quine (1908–2000) argued that singular existence is primary.

Another important division is between concrete and abstract objects. Concrete objects include rocks, plants, and people. These entities exist in space and time. They also have causal powers, meaning they can affect other things. Abstract objects include numbers and sets. These objects have no location in space and time. They also lack the ability to cause effects. Realists like Plato believe abstract objects have an independent existence. Anti-realists argue that abstract objects do not exist because they lack space, time, or causal interaction.

Existence can also be classified by necessity. An entity has necessary existence if it must exist and cannot fail to exist. This means it cannot be created or destroyed. Most things we encounter have contingent existence. A telephone or a flower is contingent. They exist now, but they did not always exist. They could also cease to exist. Some thinkers, such as Avicenna (980–1037) and Thomas Aquinas (1225–1274), argued that God has necessary existence. Baruch Spinoza (1632–1677) held a different view. He suggested that God and the world are the same and that all entities have necessary existence.

There are differing views on whether existence is a "thin" or "thick" concept. A thin concept of existence views it as a simple logical property. It might be seen as the same as self-identity. This view does not discuss the metaphysical meaning of existence. A thick concept includes a deeper metaphysical analysis. One thick proposal suggests that to exist is to be in space and time and to have effects. This view is controversial because it might exclude abstract objects like numbers. George Berkeley (1685–1753) offered a different thick view. He stated that "to be is to be perceived," suggesting all existence is mental.

History shows that these questions are very old. Discussions of existence appeared in ancient Greek Presocratic philosophy. They also appeared in ancient Indian Hindu and Buddhist philosophy. Daoist philosophy in ancient China also addressed these ideas.

The English word "existence" appeared in the late 14th century. It comes from Old French and medieval Latin roots. These roots mean "to stand forth" or "to arise." Today, existence remains relevant to logic, mathematics, epistemology, and existentialism. It continues to be a central puzzle in the study of the mind and language.