Ontology
Overview
 
Ontology is the philosophical
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

 study of the nature of being
Being
Being , is an English word used for conceptualizing subjective and objective aspects of reality, including those fundamental to the self —related to and somewhat interchangeable with terms like "existence" and "living".In its objective usage —as in "a being," or "[a] human being" —it...

, existence
Existence
In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity...

or reality
Reality
In philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible...

as such, as well as the basic categories of being
Category of being
In metaphysics , the different kinds or ways of being are called categories of being or simply categories. To investigate the categories of being is to determine the most fundamental and the broadest classes of entities...

 and their relations. Traditionally listed as a part of the major branch of philosophy known as metaphysics
Metaphysics
Metaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...

, ontology deals with questions concerning what entities exist or can be said to exist, and how such entities can be grouped, related within a hierarchy
Hierarchy
A hierarchy is an arrangement of items in which the items are represented as being "above," "below," or "at the same level as" one another...

, and subdivided according to similarities and differences.
Ontology, in analytic philosophy, concerns the determining of whether some categories of being
Category of being
In metaphysics , the different kinds or ways of being are called categories of being or simply categories. To investigate the categories of being is to determine the most fundamental and the broadest classes of entities...

are fundamental and asks in what sense the items in those categories can be said to "be".
Quotations

One is what one is, partly at least.

Samuel Beckett, in Molloy (novel)|Molloy (1951)

The genius of culture is to create an ontological system so compelling that what is inside and outside of a person are viewed as of a piece, no seams and patches noticable.

Richard Shweder, "Cultural psyschology-What is it?" Cultural Psychology (1990)

Ontology recapitulates Philology|philology.

Attributed to James Grier Miller|James Grier Miller by W.V. Quine|W.V. Quine in "Word and Object", p.viii (1960)

Encyclopedia
Ontology is the philosophical
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

 study of the nature of being
Being
Being , is an English word used for conceptualizing subjective and objective aspects of reality, including those fundamental to the self —related to and somewhat interchangeable with terms like "existence" and "living".In its objective usage —as in "a being," or "[a] human being" —it...

, existence
Existence
In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity...

or reality
Reality
In philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible...

as such, as well as the basic categories of being
Category of being
In metaphysics , the different kinds or ways of being are called categories of being or simply categories. To investigate the categories of being is to determine the most fundamental and the broadest classes of entities...

 and their relations. Traditionally listed as a part of the major branch of philosophy known as metaphysics
Metaphysics
Metaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...

, ontology deals with questions concerning what entities exist or can be said to exist, and how such entities can be grouped, related within a hierarchy
Hierarchy
A hierarchy is an arrangement of items in which the items are represented as being "above," "below," or "at the same level as" one another...

, and subdivided according to similarities and differences.

Overview

Ontology, in analytic philosophy, concerns the determining of whether some categories of being
Category of being
In metaphysics , the different kinds or ways of being are called categories of being or simply categories. To investigate the categories of being is to determine the most fundamental and the broadest classes of entities...

are fundamental and asks in what sense the items in those categories can be said to "be". It is the inquiry into being in so much as it is being, or into beings insofar as they exist—and not insofar as, for instance, particular fact
Fact
A fact is something that has really occurred or is actually the case. The usual test for a statement of fact is verifiability, that is whether it can be shown to correspond to experience. Standard reference works are often used to check facts...

s obtained about them or particular properties related to them.

Some philosophers, notably of the Platonic school
Platonism
Platonism is the philosophy of Plato or the name of other philosophical systems considered closely derived from it. In a narrower sense the term might indicate the doctrine of Platonic realism...

, contend that all nouns (including abstract nouns) refer to existent entities. Other philosophers contend that nouns do not always name entities, but that some provide a kind of shorthand for reference to a collection of either objects
Object (philosophy)
An object in philosophy is a technical term often used in contrast to the term subject. Consciousness is a state of cognition that includes the subject, which can never be doubted as only it can be the one who doubts, and some object or objects that may or may not have real existence without...

 or events
Event (philosophy)
In philosophy, events are objects in time or instantiations of properties in objects. However, a definite definition has not been reached, as multiple theories exist concerning events.-Kim’s Property-Exemplification Account of Events:...

. In this latter view, mind
Mind
The concept of mind is understood in many different ways by many different traditions, ranging from panpsychism and animism to traditional and organized religious views, as well as secular and materialist philosophies. Most agree that minds are constituted by conscious experience and intelligent...

, instead of referring to an entity, refers to a collection of mental events experienced by a person; society
Society
A society, or a human society, is a group of people related to each other through persistent relations, or a large social grouping sharing the same geographical or virtual territory, subject to the same political authority and dominant cultural expectations...

refers to a collection of persons with some shared characteristics, and geometry
Geometry
Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....

refers to a collection of a specific kind of intellectual activity. Between these poles of realism
Platonic realism
Platonic realism is a philosophical term usually used to refer to the idea of realism regarding the existence of universals or abstract objects after the Greek philosopher Plato , a student of Socrates. As universals were considered by Plato to be ideal forms, this stance is confusingly also called...

 and nominalism
Nominalism
Nominalism is a metaphysical view in philosophy according to which general or abstract terms and predicates exist, while universals or abstract objects, which are sometimes thought to correspond to these terms, do not exist. Thus, there are at least two main versions of nominalism...

, there are also a variety of other positions
Moderate realism
Moderate realism is a position in the debate on the metaphysics of universals which holds that there is no realm in which universals exist , nor do they really exist within the individuals as universals, but rather universals really exist within the particulars as individualised, and multiplied...

; but any ontology must give an account of which words refer to entities, which do not, why, and what categories result. When one applies this process to nouns such as electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...

s
, energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

, contract
Contract
A contract is an agreement entered into by two parties or more with the intention of creating a legal obligation, which may have elements in writing. Contracts can be made orally. The remedy for breach of contract can be "damages" or compensation of money. In equity, the remedy can be specific...

, happiness
Happiness
Happiness is a mental state of well-being characterized by positive emotions ranging from contentment to intense joy. A variety of biological, psychological, religious, and philosophical approaches have striven to define happiness and identify its sources....

, space
Space
Space is the boundless, three-dimensional extent in which objects and events occur and have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum...

, time
Time
Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....

, truth
Truth
Truth has a variety of meanings, such as the state of being in accord with fact or reality. It can also mean having fidelity to an original or to a standard or ideal. In a common usage, it also means constancy or sincerity in action or character...

, causality
Causality
Causality is the relationship between an event and a second event , where the second event is understood as a consequence of the first....

, and God
God
God is the English name given to a singular being in theistic and deistic religions who is either the sole deity in monotheism, or a single deity in polytheism....

, ontology becomes fundamental to many branches of philosophy.

Some fundamental questions

Principal questions of ontology are "What can be said to exist?", "Into what categories, if any, can we sort existing things?", "What are the meanings of being?", "What are the various modes of being of entities?". Various philosophers have provided different answers to these questions.

One common approach is to divide the extant subjects and predicates into groups called categories
Category of being
In metaphysics , the different kinds or ways of being are called categories of being or simply categories. To investigate the categories of being is to determine the most fundamental and the broadest classes of entities...

. Of course, such lists of categories differ widely from one another, and it is through the co-ordination of different categorical schemes that ontology relates to such fields as library science
Library and information science
Library and information science is a merging of the two fields library science and information science...

 and artificial intelligence
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

. Such an understanding of ontological categories, however, is merely taxonomic, classificatory. The categories are, properly speaking, the ways in which a being can be addressed simply as a being, such as what it is (its 'whatness', quidditas or essence), how it is (its 'howness' or qualitativeness), how much it is (quantitativeness), where it is, its relatedness to other beings, etc.

Further examples of ontological questions include:
  • What is existence
    Existence
    In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity...

    , i.e. what does it mean for a being to be?
  • Is existence a property
    Property (philosophy)
    In modern philosophy, logic, and mathematics a property is an attribute of an object; a red object is said to have the property of redness. The property may be considered a form of object in its own right, able to possess other properties. A property however differs from individual objects in that...

    ?
  • Is existence a genus or general class that is simply divided up by specific differences?
  • Which entities, if any, are fundamental? Are all entities objects?
  • How do the properties
    Property (philosophy)
    In modern philosophy, logic, and mathematics a property is an attribute of an object; a red object is said to have the property of redness. The property may be considered a form of object in its own right, able to possess other properties. A property however differs from individual objects in that...

     of an object relate to the object itself?
  • What features are the essential
    Essence
    In philosophy, essence is the attribute or set of attributes that make an object or substance what it fundamentally is, and which it has by necessity, and without which it loses its identity. Essence is contrasted with accident: a property that the object or substance has contingently, without...

    , as opposed to merely accidental attributes of a given object?
  • How many levels of existence or ontological levels are there? And what constitutes a 'level'?
  • What is a physical object
    Physical body
    In physics, a physical body or physical object is a collection of masses, taken to be one...

    ?
  • Can one give an account of what it means to say that a physical object exists?
  • Can one give an account of what it means to say that a non-physical entity exists?
  • What constitutes the identity
    Identity (philosophy)
    In philosophy, identity, from , is the relation each thing bears just to itself. According to Leibniz's law two things sharing every attribute are not only similar, but are the same thing. The concept of sameness has given rise to the general concept of identity, as in personal identity and...

    of an object?
  • When does an object go out of existence, as opposed to merely changing?
  • Do beings exist other than in the modes of objectivity and subjectivity, i.e. is the subject/object split of modern philosophy inevitable?

Concepts

Essential ontological dichotomies include:
  • Universals
    Universal (metaphysics)
    In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For example, suppose there are two chairs in a room, each of...

     and particular
    Particular
    In philosophy, particulars are concrete entities existing in space and time as opposed to abstractions. There are, however, theories of abstract particulars or tropes. For example, Socrates is a particular...

    s
  • Substance
    Substance theory
    Substance theory, or substance attribute theory, is an ontological theory about objecthood, positing that a substance is distinct from its properties. A thing-in-itself is a property-bearer that must be distinguished from the properties it bears....

     and accident
    Accident (philosophy)
    Accident, as used in philosophy, is an attribute which may or may not belong to a subject, without affecting its essence. The word "accident" has been employed throughout the history of philosophy with several distinct meanings....

  • Abstract
    Abstract object
    An abstract object is an object which does not exist at any particular time or place, but rather exists as a type of thing . In philosophy, an important distinction is whether an object is considered abstract or concrete. Abstract objects are sometimes called abstracta An abstract object is an...

     and concrete objects
  • Essence
    Essence
    In philosophy, essence is the attribute or set of attributes that make an object or substance what it fundamentally is, and which it has by necessity, and without which it loses its identity. Essence is contrasted with accident: a property that the object or substance has contingently, without...

     and existence
    Existence
    In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity...

  • Determinism
    Determinism
    Determinism is the general philosophical thesis that states that for everything that happens there are conditions such that, given them, nothing else could happen. There are many versions of this thesis. Each of them rests upon various alleged connections, and interdependencies of things and...

     and indeterminism
    Indeterminism
    Indeterminism is the concept that events are not caused, or not caused deterministically by prior events. It is the opposite of determinism and related to chance...


Etymology

While the etymology
Etymology
Etymology is the study of the history of words, their origins, and how their form and meaning have changed over time.For languages with a long written history, etymologists make use of texts in these languages and texts about the languages to gather knowledge about how words were used during...

 is Greek, the oldest extant record of the word itself is the New Latin
New Latin
The term New Latin, or Neo-Latin, is used to describe the Latin language used in original works created between c. 1500 and c. 1900. Among other uses, Latin during this period was employed in scholarly and scientific publications...

 form ontologia, which appeared in 1606, in the work Ogdoas Scholastica by Jacob Lorhard
Jacob Lorhard
Jacob Lorhard was a German philosopher and pedagogue based in St. Gallen, Switzerland....

 (Lorhardus) and in 1613 in the Lexicon philosophicum by Rudolf Göckel (Goclenius); see classical compound
Classical compound
Classical compounds are compound words composed from Latin or Ancient Greek root words. A large portion of the technical and scientific lexicon of English and other Western European languages consists of classical compounds. For example, bio- combines with -graphy to form biography...

s for this type of word formation.

The first occurrence in English of "ontology" as recorded by the OED (Oxford English Dictionary, second edition, 1989) appears in Nathaniel Bailey's dictionary of 1721, which defines ontology as ‘an Account of being in the Abstract’ - though, of course, such an entry indicates the term was already in use at the time. It is likely the word was first used in its Latin form by philosophers based on the Latin roots, which themselves are based on the Greek.
The current on-line edition of the OED (Draft Revision September 2008) gives as first occurrence in English a work by Gideon Harvey (1636/7-1702): Archelogia philosophica nova; or, New principles of Philosophy. Containing Philosophy in general, Metaphysicks or Ontology, Dynamilogy or a Discourse of Power, Religio Philosophi or Natural Theology, Physicks or Natural philosophy - London, Thomson, 1663.

Parmenides and Monism

Parmenides
Parmenides
Parmenides of Elea was an ancient Greek philosopher born in Elea, a Greek city on the southern coast of Italy. He was the founder of the Eleatic school of philosophy. The single known work of Parmenides is a poem, On Nature, which has survived only in fragmentary form. In this poem, Parmenides...

 was among the first to propose an ontological characterization of the fundamental nature of existence. In his prologue or proem he describes two views of existence
Existence
In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity...

; initially that nothing comes from nothing, and therefore existence
Existence
In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity...

 is eternal
Monism
Monism is any philosophical view which holds that there is unity in a given field of inquiry. Accordingly, some philosophers may hold that the universe is one rather than dualistic or pluralistic...

. Consequently our opinions about truth must often be false and deceitful. Most of western philosophy
Western philosophy
Western philosophy is the philosophical thought and work of the Western or Occidental world, as distinct from Eastern or Oriental philosophies and the varieties of indigenous philosophies....

, and science
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...

 - including the fundamental concepts of falsifiability
Falsifiability
Falsifiability or refutability of an assertion, hypothesis or theory is the logical possibility that it can be contradicted by an observation or the outcome of a physical experiment...

 and the conservation of energy
Conservation of energy
The nineteenth century law of conservation of energy is a law of physics. It states that the total amount of energy in an isolated system remains constant over time. The total energy is said to be conserved over time...

 - have emerged from this view. This posits that existence is what can be conceived of by thought, created, or possessed. Hence, there can be neither void nor vacuum; and true reality can neither come into being nor vanish from existence. Rather, the entirety of creation is eternal, uniform, and immutable, though not infinite (he characterized its shape as that of a perfect sphere). Parmenides thus posits that change, as perceived in everyday experience, is illusory. Everything that can be apprehended is but one part of a single entity. This idea somewhat anticipates the modern concept of an ultimate grand unification theory
Grand unification theory
The term Grand Unified Theory, often abbreviated as GUT, refers to any of several similar candidate models in particle physics in which at high-energy, the three gauge interactions of the Standard Model which define the electromagnetic, weak, and strong interactions, are merged into one single...

 that finally explains all of existence in terms of one inter-related sub-atomic
Particle physics
Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...

 reality which applies to everything.

Ontological pluralism

The opposite of eleatic monism is the pluralistic conception of Being
Being
Being , is an English word used for conceptualizing subjective and objective aspects of reality, including those fundamental to the self —related to and somewhat interchangeable with terms like "existence" and "living".In its objective usage —as in "a being," or "[a] human being" —it...

. In the 5th century BC, Anaxagoras
Anaxagoras
Anaxagoras was a Pre-Socratic Greek philosopher. Born in Clazomenae in Asia Minor, Anaxagoras was the first philosopher to bring philosophy from Ionia to Athens. He attempted to give a scientific account of eclipses, meteors, rainbows, and the sun, which he described as a fiery mass larger than...

 and Leucippus
Leucippus
Leucippus or Leukippos was one of the earliest Greeks to develop the theory of atomism — the idea that everything is composed entirely of various imperishable, indivisible elements called atoms — which was elaborated in greater detail by his pupil and successor, Democritus...

 replaced the reality of Being (unique and unchanging) with that of Becoming
Becoming (philosophy)
The concept of becoming was born in eastern ancient Greece by the philosopher Heraclitus of Hephesus, who in the Sixth century BC, said that nothing in this world is constant except change or becoming...

 and therefore by a more fundamental and elementary ontic
Ontic
In philosophy, ontic is physical, real or factual existence."Ontic" describes what is there, as opposed to the nature or properties of that being...

 plurality. This thesis originated in the Greek-ion world, stated in two different ways by Anaxagoras and by Leucippus. The first theory dealt with "seeds" (which Aristotle referred to as "homeomeries") of the various substances. The second was the atomistic theory, which dealt with reality as based on the vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...

, the atoms and their intrinsic movement in it.

The materialist Atomism
Atomism
Atomism is a natural philosophy that developed in several ancient traditions. The atomists theorized that the natural world consists of two fundamental parts: indivisible atoms and empty void.According to Aristotle, atoms are indestructible and immutable and there are an infinite variety of shapes...

 proposed by Leucippus was indeterminist
Indeterminism
Indeterminism is the concept that events are not caused, or not caused deterministically by prior events. It is the opposite of determinism and related to chance...

, but then developed by Democritus
Democritus
Democritus was an Ancient Greek philosopher born in Abdera, Thrace, Greece. He was an influential pre-Socratic philosopher and pupil of Leucippus, who formulated an atomic theory for the cosmos....

 in a deterministic
Determinism
Determinism is the general philosophical thesis that states that for everything that happens there are conditions such that, given them, nothing else could happen. There are many versions of this thesis. Each of them rests upon various alleged connections, and interdependencies of things and...

 way. It was later (4th century BC) that the original atomism was taken again as indeterministic by Epicurus
Epicurus
Epicurus was an ancient Greek philosopher and the founder of the school of philosophy called Epicureanism.Only a few fragments and letters remain of Epicurus's 300 written works...

. He confirmed the reality as composed of an infinity of indivisible, unchangeable corpuscles or atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s (atomon, lit. ‘uncuttable’), but he gives weight to characterize atoms while for Leucippus they are characterized by a "figure", an "order" and a "position" in the cosmos. They are, besides, creating the whole with the intrinsic movement in the vacuum, producing the diverse flux of being. Their movement is influenced by the Parenklisis (Lucretius names it Clinamen
Clinamen
Clinamen is the Latin name Lucretius gave to the unpredictable swerve of atoms, in order to defend the atomistic doctrine of Epicurus.According to Lucretius, the unpredictable swerve occurs "at no fixed place or time":...

) and that is determined by the chance
Randomness
Randomness has somewhat differing meanings as used in various fields. It also has common meanings which are connected to the notion of predictability of events....

. These ideas foreshadowed our understanding of traditional physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

 until the nature of atoms was discovered in the 20th century.

Plato

Plato
Plato
Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...

 developed this distinction between true reality and illusion, in arguing that what is real are eternal and unchanging Forms
Theory of Forms
Plato's theory of Forms or theory of Ideas asserts that non-material abstract forms , and not the material world of change known to us through sensation, possess the highest and most fundamental kind of reality. When used in this sense, the word form is often capitalized...

 or Ideas (a precursor to universals
Universal (metaphysics)
In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For example, suppose there are two chairs in a room, each of...

), of which things experienced in sensation are at best merely copies, and real only in so far as they copy (‘partake of’) such Forms. In general, Plato presumes that all nouns (e.g., ‘Beauty’) refer to real entities, whether sensible bodies or insensible Forms. Hence, in The Sophist
Sophist (dialogue)
The Sophist is a Platonic dialogue from the philosopher's late period, most likely written in 360 BCE. Having criticized his Theory of Forms in the Parmenides, Plato presents a new conception of the forms in the Sophist, more mundane and down-to-earth than its predecessor...

 Plato argues that Being is a Form in which all existent things participate and which they have in common (though it is unclear whether ‘Being’ is intended in the sense of existence
Existence
In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity...

, copula, or identity
Identity (philosophy)
In philosophy, identity, from , is the relation each thing bears just to itself. According to Leibniz's law two things sharing every attribute are not only similar, but are the same thing. The concept of sameness has given rise to the general concept of identity, as in personal identity and...

); and argues, against Parmenides, that Forms must exist not only of Being, but also of Negation
Negation
In logic and mathematics, negation, also called logical complement, is an operation on propositions, truth values, or semantic values more generally. Intuitively, the negation of a proposition is true when that proposition is false, and vice versa. In classical logic negation is normally identified...

 and of non-Being (or Difference).
[Aristotle's theory of universals|universals]] do not have an existence over and above the particular things
Particular
In philosophy, particulars are concrete entities existing in space and time as opposed to abstractions. There are, however, theories of abstract particulars or tropes. For example, Socrates is a particular...

 which instantiate them.

In his Categories
Categories (Aristotle)
The Categories is a text from Aristotle's Organon that enumerates all the possible kinds of thing that can be the subject or the predicate of a proposition...

, Aristotle identifies ten possible kinds of thing that can be the subject or the predicate of a proposition. For Aristotle there are four different ontological dimensions:
i) according to the various categories or ways of addressing a being as such
ii) according to its truth or falsity (e.g. fake gold, counterfeit money)
iii) whether it exists in and of itself or simply 'comes along' by accident
iv) according to its potency, movement (energy) or finished presence (Metaphysics Book Theta
Metaphysics (Aristotle)
Metaphysics is one of the principal works of Aristotle and the first major work of the branch of philosophy with the same name. The principal subject is "being qua being", or being understood as being. It examines what can be asserted about anything that exists just because of its existence and...

).

Ontological and epistemological certainty

René Descartes
René Descartes
René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...

, with "je pense donc je suis" or "cogito ergo sum
Cogito ergo sum
is a philosophical Latin statement proposed by . The simple meaning of the phrase is that someone wondering whether or not they exist is, in and of itself, proof that something, an "I", exists to do the thinking — However this "I" is not the more or less permanent person we call "I"...

" or "I think, therefore I am", argued that "the self" is something that we can know exists with epistemological certainty. Descartes argued further that this knowledge could lead to a proof of the certainty of the existence of God
God
God is the English name given to a singular being in theistic and deistic religions who is either the sole deity in monotheism, or a single deity in polytheism....

, using the ontological argument
Ontological argument
The ontological argument for the existence of God is an a priori argument for the existence of God. The ontological argument was first proposed by the eleventh-century monk Anselm of Canterbury, who defined God as the greatest possible being we can conceive...

 that had been formulated first by Anselm of Canterbury
Anselm of Canterbury
Anselm of Canterbury , also called of Aosta for his birthplace, and of Bec for his home monastery, was a Benedictine monk, a philosopher, and a prelate of the church who held the office of Archbishop of Canterbury from 1093 to 1109...

.

Certainty about the existence of "the self" and "the other", however, came under increasing criticism in the 20th century. Sociological theorists, most notably George Herbert Mead
George Herbert Mead
George Herbert Mead was an American philosopher, sociologist and psychologist, primarily affiliated with the University of Chicago, where he was one of several distinguished pragmatists. He is regarded as one of the founders of social psychology and the American sociological tradition in general.-...

 and Erving Goffman
Erving Goffman
Erving Goffman was a Canadian-born sociologist and writer.The 73rd president of American Sociological Association, Goffman's greatest contribution to social theory is his study of symbolic interaction in the form of dramaturgical perspective that began with his 1959 book The Presentation of Self...

, saw the Cartesian Other
Cartesian Other
The Cartesian Other is the counterpart to the Cartesian Self. According to Descartes, there is a divide intrinsic to human consciousness, such that you cannot ever bridge the space between your own consciousness and that of another....

 as a "Generalized Other", the imaginary audience that individuals use when thinking about the self. According to Mead, "we do not assume there is a self to begin with. Self is not presupposed as a stuff out of which the world arises. Rather the self arises in the world"
The Cartesian Other was also used by Sigmund Freud
Sigmund Freud
Sigmund Freud , born Sigismund Schlomo Freud , was an Austrian neurologist who founded the discipline of psychoanalysis...

, who saw the superego as an abstract regulatory force, and Émile Durkheim
Émile Durkheim
David Émile Durkheim was a French sociologist. He formally established the academic discipline and, with Karl Marx and Max Weber, is commonly cited as the principal architect of modern social science and father of sociology.Much of Durkheim's work was concerned with how societies could maintain...

 who viewed this as a psychologically manifested entity which represented God in society at large.

Body and environment, questioning the meaning of being

Schools of subjectivism, objectivism and relativism
Relativism
Relativism is the concept that points of view have no absolute truth or validity, having only relative, subjective value according to differences in perception and consideration....

 existed at various times in the 20th century, and the postmodernists
Postmodernism
Postmodernism is a philosophical movement evolved in reaction to modernism, the tendency in contemporary culture to accept only objective truth and to be inherently suspicious towards a global cultural narrative or meta-narrative. Postmodernist thought is an intentional departure from the...

 and body philosophers tried to reframe all these questions in terms of bodies taking some specific action in an environment. This relied to a great degree on insights derived from scientific research into animals taking instinctive action in natural and artificial settings—as studied by biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

, and cognitive science
Cognitive science
Cognitive science is the interdisciplinary scientific study of mind and its processes. It examines what cognition is, what it does and how it works. It includes research on how information is processed , represented, and transformed in behaviour, nervous system or machine...

.

The processes by which bodies related to environments became of great concern, and the idea of being
Being
Being , is an English word used for conceptualizing subjective and objective aspects of reality, including those fundamental to the self —related to and somewhat interchangeable with terms like "existence" and "living".In its objective usage —as in "a being," or "[a] human being" —it...

 itself became difficult to really define. What did people mean when they said "A is B", "A must be B", "A was B"...? Some linguists advocated dropping the verb "to be" from the English language, leaving "E Prime
E-Prime
E-Prime is a version of the English language that excludes all forms of the verb to be. E-Prime does not allow conjugations of to be , archaic forms E-Prime (short for English-Prime, sometimes denoted E′) is a version of the English language that excludes all forms of the verb to be. E-Prime does...

", supposedly less prone to bad abstractions. Others, mostly philosophers, tried to dig into the word and its usage. Heidegger
Martin Heidegger
Martin Heidegger was a German philosopher known for his existential and phenomenological explorations of the "question of Being."...

  distinguished human being as existence from the being of things in the world. Heidegger proposes that our way of being human and the way the world is for us are cast historically through a fundamental ontological questioning. These fundamental ontological categories provide the basis for communication in an age: a horizon of unspoken and seemingly unquestionable background meanings, such as human beings understood unquestioningly as subjects and other entities understood unquestioningly as objects. Because these basic ontological meanings both generate and are regenerated in everyday interactions, the locus of our way of being in a historical epoch is the communicative event of language in use. For Heidegger, however, communication in the first place is not among human beings, but language itself shapes up in response to questioning (the inexhaustible meaning of) being. Even the focus of traditional ontology on the 'whatness' or 'quidditas' of beings in their substantial, standing presence can be shifted to pose the question of the 'whoness' of human being itself.

Prominent ontologists

  • St. Anselm
  • Aquinas
  • Aristotle
    Aristotle
    Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

  • David Malet Armstrong
    David Malet Armstrong
    David Malet Armstrong , often D. M. Armstrong, is an Australian philosopher. He is well-known for his work on metaphysics and the philosophy of mind, and for his defence of a factualist ontology, a functionalist theory of the mind, an externalist epistemology, and a necessitarian conception of the...

  • Alain Badiou
    Alain Badiou
    Alain Badiou is a French philosopher, professor at European Graduate School, formerly chair of Philosophy at the École Normale Supérieure . Along with Giorgio Agamben and Slavoj Žižek, Badiou is a prominent figure in an anti-postmodern strand of continental philosophy...

  • Karen Barad
    Karen Barad
    Karen Barad is best known for her theory of Agential Realism. She is currently Professor of Feminist Studies, Philosophy, and History of Consciousness at the University of California, Santa Cruz. She is the author of Meeting the Universe Halfway: Quantum Physics and the Entanglement of Matter and...

  • Bernard Bolzano
    Bernard Bolzano
    Bernhard Placidus Johann Nepomuk Bolzano , Bernard Bolzano in English, was a Bohemian mathematician, logician, philosopher, theologian, Catholic priest and antimilitarist of German mother tongue.-Family:Bolzano was the son of two pious Catholics...

  • Franz Brentano
    Franz Brentano
    Franz Clemens Honoratus Hermann Brentano was an influential German philosopher and psychologist whose influence was felt by other such luminaries as Sigmund Freud, Edmund Husserl, Kazimierz Twardowski and Alexius Meinong, who followed and adapted his views.-Life:Brentano was born at Marienberg am...

  • Mario Bunge
    Mario Bunge
    Mario Augusto Bunge is an Argentine philosopher and physicist mainly active in Canada.-Biography:Bunge began his studies at the National University of La Plata, graduating with a Ph.D. in physico-mathematical sciences in 1952. He was professor of theoretical physics and philosophy,...

  • Rudolf Carnap
    Rudolf Carnap
    Rudolf Carnap was an influential German-born philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism....

  • Gilles Deleuze
    Gilles Deleuze
    Gilles Deleuze , was a French philosopher who, from the early 1960s until his death, wrote influentially on philosophy, literature, film, and fine art. His most popular works were the two volumes of Capitalism and Schizophrenia: Anti-Oedipus and A Thousand Plateaus , both co-written with Félix...

  • Jacques Derrida
    Jacques Derrida
    Jacques Derrida was a French philosopher, born in French Algeria. He developed the critical theory known as deconstruction and his work has been labeled as post-structuralism and associated with postmodern philosophy...

  • Rene Descartes
    René Descartes
    René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...

  • Hans-Georg Gadamer
    Hans-Georg Gadamer
    Hans-Georg Gadamer was a German philosopher of the continental tradition, best known for his 1960 magnum opus, Truth and Method .-Life:...

  • Ghazali
  • Nicolai Hartmann
    Nicolai Hartmann
    -Biography:Hartmann was born of German descent in Riga, which was then the capital of the Russian province of Livonia, and which is now in Latvia. He studied Medicine at the University of Tartu , then Philosophy in St. Petersburg and at the University of Marburg in Germany, where he took his Ph.D....


  • Georg Wilhelm Friedrich Hegel
    Georg Wilhelm Friedrich Hegel
    Georg Wilhelm Friedrich Hegel was a German philosopher, one of the creators of German Idealism. His historicist and idealist account of reality as a whole revolutionized European philosophy and was an important precursor to Continental philosophy and Marxism.Hegel developed a comprehensive...

  • Martin Heidegger
    Martin Heidegger
    Martin Heidegger was a German philosopher known for his existential and phenomenological explorations of the "question of Being."...

  • Heraclitus
    Heraclitus
    Heraclitus of Ephesus was a pre-Socratic Greek philosopher, a native of the Greek city Ephesus, Ionia, on the coast of Asia Minor. He was of distinguished parentage. Little is known about his early life and education, but he regarded himself as self-taught and a pioneer of wisdom...

  • Edmund Husserl
    Edmund Husserl
    Edmund Gustav Albrecht Husserl was a philosopher and mathematician and the founder of the 20th century philosophical school of phenomenology. He broke with the positivist orientation of the science and philosophy of his day, yet he elaborated critiques of historicism and of psychologism in logic...

  • Peter van Inwagen
    Peter van Inwagen
    Peter van Inwagen is an American analytic philosopher and the John Cardinal O'Hara Professor of Philosophy at the University of Notre Dame. He previously taught at Syracuse University and earned his PhD from the University of Rochester under the direction of Richard Taylor and Keith Lehrer...

  • Immanuel Kant
    Immanuel Kant
    Immanuel Kant was a German philosopher from Königsberg , researching, lecturing and writing on philosophy and anthropology at the end of the 18th Century Enlightenment....

  • Gottfried Leibniz
    Gottfried Leibniz
    Gottfried Wilhelm Leibniz was a German philosopher and mathematician. He wrote in different languages, primarily in Latin , French and German ....

  • Leucippus
    Leucippus
    Leucippus or Leukippos was one of the earliest Greeks to develop the theory of atomism — the idea that everything is composed entirely of various imperishable, indivisible elements called atoms — which was elaborated in greater detail by his pupil and successor, Democritus...

  • David Kellogg Lewis
    David Kellogg Lewis
    David Kellogg Lewis was an American philosopher. Lewis taught briefly at UCLA and then at Princeton from 1970 until his death. He is also closely associated with Australia, whose philosophical community he visited almost annually for more than thirty years...

  • E.J. Lowe
  • Alexius Meinong
    Alexius Meinong
    Alexius Meinong was an Austrian philosopher, a realist known for his unique ontology...

  • Alfred North Whitehead
    Alfred North Whitehead
    Alfred North Whitehead, OM FRS was an English mathematician who became a philosopher. He wrote on algebra, logic, foundations of mathematics, philosophy of science, physics, metaphysics, and education...

  • William of Ockam
  • Parmenides
    Parmenides
    Parmenides of Elea was an ancient Greek philosopher born in Elea, a Greek city on the southern coast of Italy. He was the founder of the Eleatic school of philosophy. The single known work of Parmenides is a poem, On Nature, which has survived only in fragmentary form. In this poem, Parmenides...

  • Charles Sanders Peirce

  • Plato
    Plato
    Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...

  • Plotinus
    Plotinus
    Plotinus was a major philosopher of the ancient world. In his system of theory there are the three principles: the One, the Intellect, and the Soul. His teacher was Ammonius Saccas and he is of the Platonic tradition...

  • Proclus
    Proclus
    Proclus Lycaeus , called "The Successor" or "Diadochos" , was a Greek Neoplatonist philosopher, one of the last major Classical philosophers . He set forth one of the most elaborate and fully developed systems of Neoplatonism...

  • Friedrich Nietzsche
    Friedrich Nietzsche
    Friedrich Wilhelm Nietzsche was a 19th-century German philosopher, poet, composer and classical philologist...

  • W. V. O. Quine
  • Bertrand Russell
    Bertrand Russell
    Bertrand Arthur William Russell, 3rd Earl Russell, OM, FRS was a British philosopher, logician, mathematician, historian, and social critic. At various points in his life he considered himself a liberal, a socialist, and a pacifist, but he also admitted that he had never been any of these things...

  • Gilbert Ryle
    Gilbert Ryle
    Gilbert Ryle , was a British philosopher, a representative of the generation of British ordinary language philosophers that shared Wittgenstein's approach to philosophical problems, and is principally known for his critique of Cartesian dualism, for which he coined the phrase "the ghost in the...

  • Jean-Paul Sartre
    Jean-Paul Sartre
    Jean-Paul Charles Aymard Sartre was a French existentialist philosopher, playwright, novelist, screenwriter, political activist, biographer, and literary critic. He was one of the leading figures in 20th century French philosophy, particularly Marxism, and was one of the key figures in literary...

  • Jonathan Schaffer
    Jonathan Schaffer
    Jonathan Schaffer is an American philosopher specializing in Metaphysics and Epistemology.Since earning his PhD. from Rutgers in 1999, Schaffer has published 37 papers. He wrote his dissertation - "Causation and the Probabilities of Processes" - under Brian McLaughin. David Lewis served as...

  • Duns Scotus
    Duns Scotus
    Blessed John Duns Scotus, O.F.M. was one of the more important theologians and philosophers of the High Middle Ages. He was nicknamed Doctor Subtilis for his penetrating and subtle manner of thought....

  • Theodore Sider
    Theodore Sider
    Theodore Sider is an American philosopher specializing in Metaphysics and Philosophy of Language.Since earning his PhD. from the University of Massachusetts Amherst in 1993, Sider has published three books and forty-seven papers. He has also edited a textbook in metaphysics with John Hawthorne and...

  • Baruch Spinoza
    Baruch Spinoza
    Baruch de Spinoza and later Benedict de Spinoza was a Dutch Jewish philosopher. Revealing considerable scientific aptitude, the breadth and importance of Spinoza's work was not fully realized until years after his death...

  • African Spir
    African Spir
    Afrikan Aleksandrovich Špir was a Russian Neo-Kantian philosopher of German descent who wrote primarily in German...

  • Ludwig Wittgenstein
    Ludwig Wittgenstein
    Ludwig Josef Johann Wittgenstein was an Austrian philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. He was professor in philosophy at the University of Cambridge from 1939 until 1947...

  • Dean Zimmerman
    Dean Zimmerman
    Dean Zimmerman is an American professor of philosophy at Rutgers University. He specializes in metaphysics and the philosophy of religion. He earned his PhD in philosophy from Brown University, and has taught at the University of Notre Dame and Syracuse University...

  • Ernst Cassirer
    Ernst Cassirer
    Ernst Cassirer was a German philosopher. He was one of the major figures in the development of philosophical idealism in the first half of the 20th century...



See also

  • Applied ontology
    Applied ontology
    Applied ontology involves the practical application of ontological resources to specific domains, such as biomedicine or geography. Much work in applied ontology is carried out within the framework of the semantic web...

  • Foundation ontology
  • Geopolitical ontology
    Geopolitical ontology
    A geopolitical ontology is a mechanism to describe, manage and exchange data related to geopolitical entities such as countries, territories, regions and other similar areas.-Definitions and examples:...

  • Holism
    Holism
    Holism is the idea that all the properties of a given system cannot be determined or explained by its component parts alone...

  • Mereology
    Mereology
    In philosophy and mathematical logic, mereology treats parts and the wholes they form...

  • Meta-ontology
    Meta-ontology
    Metaontology is the branch of metaphysics that deals with the nature of ontology and ontological questions. The term owes its popularization to Peter van Inwagen's 1998 paper of the same name. However, the subject itself is much older, going back at least to Rudolf Carnap's distinction,...

  • Metamodeling
    Metamodeling
    Metamodeling, or meta-modeling in software engineering and systems engineering among other disciplines, is the analysis, construction and development of the frames, rules, constraints, models and theories applicable and useful for modeling a predefined class of problems...


  • Modal logic
    Modal logic
    Modal logic is a type of formal logic that extends classical propositional and predicate logic to include operators expressing modality. Modals — words that express modalities — qualify a statement. For example, the statement "John is happy" might be qualified by saying that John is...

  • Nihilism
    Nihilism
    Nihilism is the philosophical doctrine suggesting the negation of one or more putatively meaningful aspects of life. Most commonly, nihilism is presented in the form of existential nihilism which argues that life is without objective meaning, purpose, or intrinsic value...

  • Ontological paradox
  • Philosophy of mathematics
    Philosophy of mathematics
    The philosophy of mathematics is the branch of philosophy that studies the philosophical assumptions, foundations, and implications of mathematics. The aim of the philosophy of mathematics is to provide an account of the nature and methodology of mathematics and to understand the place of...

  • Philosophy of science
    Philosophy of science
    The philosophy of science is concerned with the assumptions, foundations, methods and implications of science. It is also concerned with the use and merit of science and sometimes overlaps metaphysics and epistemology by exploring whether scientific results are actually a study of truth...

  • Philosophy of space and time
    Philosophy of space and time
    Philosophy of space and time is the branch of philosophy concerned with the issues surrounding the ontology, epistemology, and character of space and time. While such ideas have been central to philosophy from its inception, the philosophy of space and time was both an inspiration for and a...

  • Physical ontology

  • Quantum ontology
  • Solipsism
    Solipsism
    Solipsism is the philosophical idea that only one's own mind is sure to exist. The term comes from Latin solus and ipse . Solipsism as an epistemological position holds that knowledge of anything outside one's own mind is unsure. The external world and other minds cannot be known, and might not...

  • Speculative realism
    Speculative realism
    Speculative realism is an emerging movement in contemporary philosophy which defines itself loosely in its stance of metaphysical realism against the dominant forms of post-Kantian philosophy or what it terms correlationism. Speculative realism takes its name from a conference held at Goldsmiths...

  • Structure and agency
    Structure and agency
    The question over the primacy of either structure or agency in human behavior is a central debate in the social sciences. In this context, "agency" refers to the capacity of individuals to act independently and to make their own free choices. "Structure", by contrast, refers to the recurrent...

  • Taxonomy
    Taxonomy
    Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...

  • Upper ontology


External links

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