Existence is the ability of an entity to interact with physical reality. In philosophy, it refers to the ontological property[1] of being.[2]
Materialism holds that the only things that exist are matter and energy, that all things are composed of material, that all actions require energy, and that all phenomena (including consciousness) are the result of the interaction of matter. Dialectical materialism does not make a distinction between being and existence, and defines it as the objective reality of various forms of matter.[2]
Idealism holds that the only things that exist are thoughts and ideas, while the material world is secondary.[4][5] In idealism, existence is sometimes contrasted with transcendence, the ability to go beyond the limits of existence.[2] As a form of epistemological idealism, rationalism interprets existence as cognizable and rational, that all things are composed of strings of reasoning, requiring an associated idea of the thing, and all phenomena (including consciousness) are the result of an understanding of the imprint from the noumenalworld in which lies beyond the thing-in-itself.
In scholasticism, existence of a thing is not derived from its essence but is determined by the creative volition of God, the dichotomy of existence and essence demonstrates that the dualism of the created universe is only resolvable through God.[2] Empiricism recognizes existence of singular facts, which are not derivable and which are observable through empirical experience.
The exact definition of existence is one of the most important and fundamental topics of ontology, the philosophical study of the nature of being, existence, or reality in general, as well as of the basic categories of being and their relations. Traditionally listed as a part of the major branch of philosophy known as metaphysics, ontology deals with questions concerning what things or entities exist or can be said to exist, and how such things or entities can be grouped, related within a hierarchy, and subdivided according to similarities and differences.
In the Western tradition of philosophy, the earliest known comprehensive treatments of the subject are from Plato's Phaedo, Republic, and Statesman and Aristotle's Metaphysics, though earlier fragmentary writing exists. Aristotle developed a comprehensive theory of being, according to which only individual things, called substances, fully have to be, but other things such as relations, quantity, time, and place (called the categories) have a derivative kind of being, dependent on individual things. In Aristotle's Metaphysics, there are four causesof existence or change in nature: the material cause, the formal cause, the efficient cause and the final cause.