ontology

The study of the existence of being.

The subject of ontology is the study of the categories of things that exist or may exist in some domain. The product of such a study, called an ontology, is a catalog of the types of things that are assumed to exist in a domain of interest D from the perspective of a person who uses a language L for the purpose of talking about D.
- Sowa, John F., Ontology, (2005), Retrieved January 2, 2007 at http://www.jfsowa.com/ontology/index.htm, Last Modified: 06/07/2003 20:57:07

Other definitionsnew --

1. a systematic account of existence.
2. An explicit formal specification of how to represent the objects, concepts and other entities that are assumed to exist in some area of interest and the relationships that hold among them.
3. The hierarchical structuring of knowledge about things by subcategorising them according to their essential (or at least relevant and/or cognitive) qualities.

Source: ontology. Dictionary.com. The Free On-line Dictionary of Computing. Denis Howe. http://dictionary.reference.com/browse/ontology (accessed: December 29, 2006).

Discusson --
Ontology is the study of being or existence. It seeks to describe or posit the basic categories and relationships of being or existence to define entities and types of entities within its framework. Ontology can be said to study conceptions of reality. Some philosophers, notably of the Platonic school, contend that all nouns refer to entities. Other philosophers contend that some nouns do not name entities but provide a kind of shorthand way of referring 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. 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, time, truth, causality, and God, ontology becomes fundamental to many branches of philosophy.

Ontology's fundamnental question --
Ontology has one basic question: ""What is there?"" Different philosophers provide different answers to this question.

Approach to ontology --
One common approach is to divide the extant entities into groups called ""categories"". However, these lists of categories are also quite different from one another. It is in this latter sense that ontology is applied to such fields as theology, information science and artificial intelligence.

Ontological questions --
Further examples of ontological questions include:

• What is existence?
• Is existence a property?
• Why does something exist rather than nothing?
• What constitutes the identity of an object?
• What is a physical object?
• What features are the essential, as opposed to merely accidental, attributes of a given object?
• Can one give an account of what it means to say that a physical object exists?
• What are an object's properties or relations and how are they related to the object itself?
• When does an object go out of existence, as opposed to merely changing?
• Do souls exist?

-- Wikipedia contributors, ""Ontology,"" Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=Ontology&oldid=96948799 (accessed January 1, 2007).