Editing Ontology (section)

=== Concrete and abstract objects ===
{{Main|Abstract and concrete|l1=Concrete and abstract}}
Concrete objects are entities that exist in space and time, such as a tree, a car, and a planet. They have causal powers and can affect each other, like when a car hits a tree and both are deformed in the process. Abstract objects, by contrast, are outside space and time, such as the number 7 and the set of [[integer]]s. They lack causal powers and do not undergo changes.<ref>{{multiref | {{harvnb|Mackie|1998|loc=Lead Section}} | {{harvnb|Falguera|Martínez-Vidal|Rosen|2022|loc=[https://plato.stanford.edu/entries/abstract-objects/ lead section, § 1. Introduction]}} | {{harvnb|Faye|2013|pp=[https://books.google.com/books?id=ftrmBQAAQBAJ&pg=PA89 89–91]}} | {{harvnb|Prior|2006|pp=498–499}} | {{harvnb|Oliver|2005|p=3}} }}</ref>{{efn|The precise definition is disputed.<ref>{{harvnb|Oliver|2005|p=3}}</ref>}} The existence and nature of abstract objects remain subjects of philosophical debate.<ref>{{multiref | {{harvnb|Oliver|2005|p=3}} | {{harvnb|Plebani|2013|p=[https://books.google.com/books?id=pkNb_3NYyz0C&pg=PA5 5]}} }}</ref>

Concrete objects encountered in everyday life are complex entities composed of various parts. For example, a book is made up of two covers and the pages between them. Each of these components is itself constituted of smaller parts, like [[molecule]]s, [[atom]]s, and [[elementary particle]]s.<ref>{{multiref | {{harvnb|Cornell|loc=Lead Section}} | {{harvnb|Loux|Crisp|2017|pp=250–251}} | {{harvnb|Varzi|2019|loc=Lead Section, § 1. 'Part' and Parthood}} | {{harvnb|Cornell|loc=Lead Section, § 2. The Special Composition Question}} | {{harvnb|Tallant|2017|pp=19–21}} }}</ref> [[Mereology]] studies the relation between parts and wholes. One position in mereology says that every collection of entities forms a whole. According to another view, this is only the case for collections that fulfill certain requirements, for instance, that the entities in the collection touch one another.<ref>{{multiref |  {{harvnb|Loux|Crisp|2017|pp=82–83}} | {{harvnb|Cornell|loc=Lead Section, § 2. The Special Composition Question}} | {{harvnb|Brenner|2015|p=1295}} | {{harvnb|Tallant|2017|pp=19–21, 23–24, 32–33}} | {{harvnb|Cornell|loc=Lead Section}}}}</ref> The problem of material constitution asks whether or in what sense a whole should be considered a new object in addition to the collection of parts composing it.<ref>{{multiref | {{harvnb|Rea|1997|pp=[https://books.google.com/books?id=a0QOWVtDOXYC&pg=PR15 xv–xvi]}} | {{harvnb|Korman|2021|loc=Lead Section}} }}</ref>

Abstract objects are closely related to fictional and [[Object of the mind|intentional objects]]. Fictional objects are entities invented in works of [[fiction]]. They can be things, like the [[One Ring]] in [[J. R. R. Tolkien]]'s book series [[The Lord of the Rings]], and people, like the [[Monkey King]] in the novel [[Journey to the West]].<ref>{{multiref | {{harvnb|Kroon|Voltolini|2023|loc=Lead Section}} | {{harvnb|Lamarque|1998|loc=Lead Section}} | {{harvnb|Prior|2006|p=493}} }}</ref> Some philosophers say that fictional objects are abstract objects and exist outside space and time. Others understand them as artifacts that are created as the works of fiction are written.<ref>{{multiref | {{harvnb|Kroon|Voltolini|2023|loc=§ 1. The Metaphysics of Fictional Entities}} | {{harvnb|Lamarque|1998|loc=§ 3. Hospitable theories}} }}</ref> Intentional objects are entities that exist within [[mental states]], like [[perception]]s, [[belief]]s, and [[desire]]s. For example, if a person thinks about the [[Loch Ness Monster]] then the Loch Ness Monster is the intentional object of this [[thought]]. People can think about existing and non-existing objects. This makes it difficult to assess the [[Intentionality#The problem of intentional inexistence|ontological status of intentional objects]].<ref>{{multiref | {{harvnb|Jacob|2023|loc=2. Intentional inexistence}} | {{harvnb|Kriegel|2007|pp=307–308}} | {{harvnb|O’Madagain|loc=§ 2. Intentional Objects}} }}</ref>