What is Ontology?


Ontology (from the "being; that which is", present participle of the verb "be", and "science, study, theory") is the philosophical study of the nature of being, becoming, existence, or reality, as well as 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 entities exist or can be said to exist, and how such entities can be grouped, related within a hierarchy, and subdivided according to similarities and differences.



Ontology, in analytic philosophy, concerns the determination whether some categories of being are fundamental and asks in what sense can the items in those categories be said to "be." It is the inquiry into being in so much as it is being ("being qua being"), or into beings insofar as they exist—and not insofar as, for instance, particular facts can be obtained about them or particular properties belong to them.


Some philosophers, notably of the Platonic school, 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 or events. In this latter view, mind, instead of referring to an entity, refers to a collection of mental events experienced by a person; society refers to a collection of persons with some shared characteristics, and geometry refers to a collection of a specific kind of intellectual activity.


Between these poles of realism and nominalism, there are also a variety of other positions; 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 electrons, energy, contract, happiness, space, time, truth, causality, and God, 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. 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 and artificial intelligence. 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, i.e. what does it mean for a being to be?

  • Is existence a property?

  • 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 of an object relate to the object itself?

  • What features are the essential, 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?

  • 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 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?



Essential ontological dichotomies include:


  • Universals and particulars

  • Substance and accident

  • Abstract and concrete objects

  • Essence and existence

  • Determinism and indeterminism

Ontological Approaches


Social scientists adopt one of four main ontological approaches:


  1. Realism (the idea that facts are out there just waiting to be discovered).

  2. Empiricism (the idea that we can observe the world and evaluate those observations in relation to facts).

  3. Positivism (which focuses on the observations themselves, attentive more to claims about facts than to facts themselves).

  4. Post-modernism (which holds that facts are fluid and elusive, so we should focus only on our observational claims).





Ontologies are classified in various ways using criteria such as the degree of abstraction and field of application:


  1. Upper ontology: concepts supporting development of an ontology, meta-ontology.

  2. Domain ontology: concepts relevant to a particular topic or area of interest, for example, information technology or computer languages, or particular branches of science.

  3. Interface ontology: concepts relevant to the juncture of two disciplines.

  4. Process ontology: inputs, outputs, constraints, sequencing information, involved in business or engineering processes.

Aristotle, Plato, Martine Heidegger, Friedrich Hegel and Jean-Paul Sartre are some prominent ontologists.


Information collected from wikipedia.org