Editing Ontology (section)

=== Particulars and universals ===
{{main|Particular|Universal (metaphysics)|l1=Particulars|l2=Universals}}

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|footer            = The [[Taj Mahal]] is a particular entity while the color ''green'' is a universal entity.
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A central distinction in ontology is between particular and universal entities. Particulars, also called ''individuals'', are unique, non-repeatable entities, like [[Socrates]], the [[Taj Mahal]], and [[Mars]].<ref>{{multiref | {{harvnb|Lowe|2005|p=683}} | {{harvnb|MacLeod|Rubenstein|loc=Lead Section, § 1a. The Nature of Universals}} | {{harvnb|Bigelow|1998|loc=Lead Section}} | {{harvnb|Campbell|2006|loc=§ Particularity and Individuality}} | {{harvnb|Maurin|2019|loc=Lead Section}} }}</ref> Universals are general, repeatable entities, like the color ''green'', the form ''circularity'', and the virtue ''courage''. Universals express aspects or features shared by particulars. For example, [[Mount Everest]] and [[Mount Fuji]] are particulars characterized by the universal ''mountain''.<ref>{{multiref | {{harvnb|MacLeod|Rubenstein|loc=Lead Section}} | {{harvnb|Bigelow|1998a|loc=Lead Section}} | {{harvnb|Cowling|2019|loc=Lead Section}} | {{harvnb|Loux|Crisp|2017|pp=17–19}} }}</ref>

Universals can take the form of properties or relations.<ref>{{multiref | {{harvnb|Campbell|2006|pp=24–25}} | {{harvnb|Bigelow|1998|loc=Lead Section}} }}</ref>{{efn|This idea is opposed by trope theorists, who understand properties and relations as particular entities.<ref>{{harvnb|Campbell|2006|p=25}}</ref>}} Properties describe the characteristics of things. They are features or qualities possessed by an entity.<ref>{{multiref | {{harvnb|Campbell|2006|p=24}} | {{harvnb|Orilia|Paolini Paoletti|2022|loc=Lead Section}} }}</ref> Properties are often divided into [[Property (philosophy)#Essential and accidental|essential and accidental properties]]. A property is essential if an entity must have it; it is accidental if the entity can exist without it.<ref>{{harvnb|Orilia|Paolini Paoletti|2022|loc=§ 1.7 Kinds of Properties}}</ref> For instance, ''having three sides'' is an essential property of a triangle, whereas ''being red'' is an accidental property.<ref>{{harvnb|Vaidya|Wallner|2024|p=[https://books.google.com/books?id=W34IEQAAQBAJ&pg=PA473 473]}}</ref>{{efn|Other influential distinctions are between intrinsic and extrinsic properties, between determinate or determinable properties, and between categorical and dispositional properties.<ref>{{multiref | {{harvnb|Orilia|Paolini Paoletti|2022|loc=§ 1.7 Kinds of Properties, § 5.2. Essentially Categorical vs. Essentially Dispositional Properties}} | {{harvnb|Marshall|Weatherson|2023|loc=Lead Section}} }}</ref>}} Relations are ways how two or more entities stand to one another. Unlike properties, they apply to several entities and characterize them as a group.<ref>{{multiref | {{harvnb|Sider|2010|p=[https://books.google.com/books?id=-KkPEAAAQBAJ&pg=PA13 13]}} | {{harvnb|Bogen|2005|p=798}} | {{harvnb|MacBride|2020|loc=lead section}} | {{harvnb|Campbell|2006|p=25}} }}</ref> For example, ''being a city'' is a property while ''being east of'' is a relation, as in "[[Kathmandu]] is a city" and "Kathmandu is east of [[New Delhi]]".<ref>{{harvnb|MacBride|2020|loc=§ 2. Eliminativism, External Relations and Bradley’s Regress}}</ref> Relations are often divided into [[Relation (philosophy)#Internal and external|internal and external relations]]. Internal relations depend only on the properties of the objects they connect, like the relation of [[Similarity (philosophy)|resemblance]]. External relations express characteristics that go beyond what the connected objects are like, such as spatial relations.<ref>{{multiref | {{harvnb|MacBride|2020|loc=§1. Preliminary Distinctions}} | {{harvnb|Heil|2009|p=316}} | {{harvnb|Armstrong|2010|pp=24–25}} }}</ref>

Substances{{efn|The term ''substance'' has a specific meaning in philosophy distinct from ordinary language expressions such as ''chemical substance'' or ''substance abuse''.<ref>{{harvnb|O'Conaill|2022|p=1}}</ref>}} play an important role in the history of ontology as the particular entities that underlie and support properties and relations. They are often considered the fundamental building blocks of reality that can exist on their own, while entities like properties and relations cannot exist without substances. Substances persist through changes as they acquire or lose properties. For example, when a tomato ripens, it loses the property ''green'' and acquires the property ''red''.<ref>{{multiref | {{harvnb|Campbell|2006|pp=23–24}} | {{harvnb|O'Conaill|2022|pp=1–2, 12–13, 29}} | {{harvnb|Robinson|Weir|2024|loc=Lead Section}} }}</ref>

States of affairs are complex particular entities that have several other entities as their components. The state of affairs "Socrates is wise" has two components: the individual ''Socrates'' and the property ''wise''. States of affairs that correspond to reality are called ''[[fact]]s''.<ref>{{multiref | {{harvnb|Campbell|2006|p=25}} | {{harvnb|Textor|2021|loc=Lead Section}} }}</ref>{{efn|David Armstrong and his followers use a different terminology that does not distinguish between states of affairs and facts.<ref>{{harvnb|Textor|2021|loc=Lead Section}}</ref>}} Facts are [[Truthmaker theory|truthmakers]] of statements, meaning that whether a statement is true or false depends on the underlying facts.<ref>{{harvnb|Textor|2021|loc=Lead Section}}</ref>

Events are particular entities{{efn|Some ontologists also use the term in a less common sense to refer to universals in the form of event types.<ref>{{harvnb|Mackie|2005|p=272}}</ref>}} that occur in time, like the [[fall of the Berlin Wall]] and the [[first moon landing]]. They usually involve some kind of change, like the lawn becoming dry. In some cases, no change occurs, like the lawn staying wet.<ref>{{multiref | {{harvnb|Mackie|2005|p=272}} | {{harvnb|Campbell|2006|p=25}} }}</ref> Complex events, also called ''processes'', are composed of a sequence of events.<ref>{{harvnb|Campbell|2006|p=25}}</ref>