Ontology

Part of a series on
Philosophy
Philosophy portal Contents Outline Lists Glossary History Categories Disambiguation
Philosophies By period Ancient Ancient Egyptian Ancient Greek Medieval Renaissance Modern Contemporary Analytic Continental By region African Egypt Ethiopia South Africa Eastern philosophy Chinese Indian Indonesia Japan Korea Vietnam Indigenous American Aztec philosophy Middle Eastern philosophy Iranian Western American British French German Italian Russian By religion Buddhist Confucian Christian Hindu Islamic Jain Jewish Taoist
Branches Epistemology Ethics Logic Metaphysics Aesthetics Education History Language Law Metaphilosophy Mind Ontology Phenomenology Political Religion Science
Philosophers Aestheticians Epistemologists Ethicists Logicians Metaphysicians Philosophers of mind Social and political philosophers Women in philosophy
v t e

In metaphysics, ontology is the philosophical study of being. It investigates what types of entities exist, how they are grouped into categories, and how they are related to one another on the most fundamental level (and whether there even is a fundamental level).^[1] Ontologists often try to determine what the categories or highest kinds are and how they form a system of categories that encompasses the classification of all entities. Commonly proposed categories include substances, properties, relations, states of affairs, and events. These categories are characterized by fundamental ontological concepts, including particularity and universality, abstractness and concreteness, or possibility and necessity. Of special interest is the concept of ontological dependence, which determines whether the entities of a category exist on the most fundamental level. Disagreements within ontology are often about whether entities belonging to a certain category exist and, if so, how they are related to other entities.^[2]

When used as a countable noun, the words ontology and ontologies refer not to the science of being but to theories within the science of being. Ontological theories can be divided into various types according to their theoretical commitments. Monocategorical ontologies hold that there is only one basic category, but polycategorical ontologies rejected this view. Hierarchical ontologies assert that some entities exist on a more fundamental level and that other entities depend on them. Flat ontologies, on the other hand, deny such a privileged status to any entity.