Editing Existence (section)

=== Physical and mental ===
Entities that exist on a physical level include objects encountered in everyday life, like stones, trees, and human bodies, as well as entities discussed in [[modern physics]], like electrons and protons.<ref>{{harvnb|Mackie|1998|loc=Lead Section}}</ref>{{efn|According to the [[Standard Model]] of [[particle physics]], [[elementary particles]] together with the [[four fundamental forces]] acting on them are the most basic constituents of the universe. [[String theory]] provides an alternative explanation by focusing one-dimensional [[String (physics)|strings]] and their interactions.<ref>{{multiref | {{harvnb|Martin|Wells|2022|pp=[https://books.google.com/books?id=xVyYEAAAQBAJ&pg=PA1 1–4]}} | {{harvnb|Schwichtenberg|2017|pp=[https://books.google.com/books?id=bipBDwAAQBAJ&pg=PA8 7–8]}} | {{harvnb|Chang|2024|pp=[https://books.google.com/books?id=c2L8EAAAQBAJ&pg=PA247 247]}} }}</ref>}} Physical entities can be observed and measured; they possess mass and a location in space and time.<ref>{{multiref |1={{harvnb|Smart|2023|loc=Lead Section, §Types of Materialist Theory}} |2={{harvnb|Markosian|2009|pp=[https://books.google.com/books?id=lQ2xDwAAQBAJ 486–487]|loc=Physical Object}} }}</ref> Mental entities like perceptions, experiences of pleasure and pain as well as beliefs, desires, and emotions belong to the realm of the mind; they are primarily associated with conscious experiences but also include unconscious states like unconscious beliefs, desires, and memories.<ref>{{multiref | {{harvnb|Kim|2006|loc=[https://philpapers.org/rec/KIMPOM-3 § 1. Introduction]}} | {{harvnb|Addis|2013|pp=[https://books.google.com/books?id=Vk6ZEN6vByUC&pg=PA49 49–50]}} | {{harvnb|Searle|2004|p=[https://books.google.com/books?id=5G_iBwAAQBAJ&pg=PT183 183]}} }}</ref>

The [[mind–body problem]] concerns the ontological status of and relation between physical and mental entities and is a frequent topic in [[metaphysics]] and [[philosophy of mind]].{{efn|Philosophy of mind is the branch of philosophy that studies the nature of mental phenomena and how they are related to the physical world.<ref>{{multiref | {{harvnb|Lowe|2000|pp=[https://books.google.com/books?id=mH12kYm1RKAC&pg=PA1 1–2]}} | {{harvnb|Crumley|2006|pp=[https://books.google.com/books?id=Yf4eAAAAQBAJ&pg=PA2 2–3]}} }}</ref>}} According to [[materialists]], only physical entities exist on the most-fundamental level. Materialists usually explain mental entities in terms of physical processes; for example, as brain states or as patterns of neural activation.<ref>{{multiref | {{harvnb|Kelly|2004|pp=[https://books.google.com/books?id=AFwr3CCoqAEC&pg=PA87 87–88]}} | {{harvnb|Smart|2023|loc=Lead Section, § Types of Materialist Theory}} }}</ref> Idealism,{{efn|Some theorists use the term "ontological idealism" to distinguish it from idealistic views in epistemology.<ref>{{harvnb|Berendzen|2023|p=[https://books.google.com/books?id=C0DAEAAAQBAJ&pg=PA17 17]}}</ref>}} a minority view in contemporary philosophy,<ref>{{harvnb|Guyer|Horstmann|2023|loc=§ 9. The Fate of Idealism in the Twentieth Century}}</ref> rejects matter as ultimate and views the mind as the most basic reality.<ref>{{harvnb|Sprigge|1998|loc=Lead Section|ps=, "Idealism is now usually understood in philosophy as the view that mind is the most basic reality and that the physical world exists only as an appearance to or expression of mind, or as somehow mental in its inner essence."}}</ref> [[Dualists]] like [[René Descartes]] (1596–1650) believe both physical and mental entities exist on the most-fundamental level. They state they are connected to one another in several ways but that one cannot be reduced to the other.<ref>{{multiref | {{harvnb|Kelly|2004|pp=[https://books.google.com/books?id=AFwr3CCoqAEC&pg=PA87 87–88]}} | {{harvnb|Calef|loc=Lead Section, § 3. Descartes’ Dualism}} }}</ref>