Existence

Existence is the state of being real, as opposed to nonexistence or nonbeing. It is often distinguished from essence: an entity’s essence consists of its defining features, which can be understood without knowing whether the entity actually exists. The philosophical study of existence—its nature and varieties—is called ontology.

Existence can be singular, referring to individual entities, or general, referring to concepts or universals. Entities that occupy space and time have concrete existence, while abstract entities like numbers and sets do not. Other distinctions include possible, contingent, and necessary existence, as well as physical versus mental existence. Most philosophers hold that something either exists or does not, with no middle ground, but some argue for degrees of existence, meaning certain entities exist more fully than others.

The orthodox view in ontology treats existence as a second-order property—a property of properties. To say lions exist, for example, means the property of being a lion is instantiated by at least one entity. An alternative view sees existence as a first-order property, like color or shape, belonging to individuals. Alexius Meinong and his followers adopt this position, claiming that some individuals—such as Santa Claus—do not exist. Universalists reject this, holding that existence is a property every individual possesses.

The concept of existence has been debated throughout philosophy’s history, appearing in ancient Greek, Hindu, Buddhist, and Daoist thought. It remains relevant to logic, mathematics, epistemology, philosophy of mind, philosophy of language, and existentialism.

Existence is also defined as the state of being real, setting actual entities apart from imaginary ones. The word comes from the medieval Latin *ex(s)istere*, meaning “to stand forth,” “to appear,” or “to arise,” entering English in the late 14th century via Old French. Terms like being, reality, and actuality are often used as synonyms, but their exact relationship to existence is disputed. Meinong held that all entities have being, but not all have existence—merely possible objects like Santa Claus have being without existing. Takashi Yagisawa contrasts existence with reality, viewing reality as more fundamental and existence as a relative term linking an entity to its world. Gottlob Frege considered actuality narrower than existence, since only actual entities can cause or undergo change, unlike non-actual existents such as numbers. Some philosophers, including Edmund Husserl, argue existence is an elementary concept that cannot be defined without circularity, making nontrivial discussion of its nature difficult.

These disputes are reflected in the distinction between thin and thick concepts of existence. Thin concepts treat existence as a logical property shared by all existing things, without metaphysical content—for instance, equating existence with self-identity. Thick concepts add metaphysical analysis: one proposal holds that to exist is to be present in space and time and to have effects; this is controversial because it would deny existence to abstract objects like numbers. George Berkeley offered another thick concept: “to be is to be perceived,” meaning all existence is mental.

Existence contrasts with nonexistence, a lack of reality. Whether objects can be divided into existent and nonexistent is debated; some use this distinction to explain thinking about fictional objects like dragons, but the idea of nonexistent objects is not widely accepted and is sometimes considered contradictory. Related terms include nothingness and nonbeing. Existence is often linked to mind-independent reality, though mind-dependent existence—such as an idea in a person’s mind—is also possible. Some idealists extend this to all of reality.

Finally, existence is contrasted with essence. Essence is the intrinsic nature or defining qualities of an entity, determining what kind of thing it is. Essence answers what an entity is, while existence answers that it is. One can understand an object’s nature without knowing whether it exists.