
Reality is the sum or aggregate of
everything
Everything, every-thing, or every thing, is all that exists; it is an antithesis of ''nothing'', or its complement. It is the totality of things relevant to some subject matter. Without expressed or implied limits, it may refer to . The uni ...
in
existence
Existence is the state of having being or reality in contrast to nonexistence and nonbeing. Existence is often contrasted with essence: the essence of an entity is its essential features or qualities, which can be understood even if one does ...
; everything that is not
imaginary. Different
cultures
Culture ( ) is a concept that encompasses the social behavior, institutions, and Social norm, norms found in human societies, as well as the knowledge, beliefs, arts, laws, Social norm, customs, capabilities, Attitude (psychology), attitudes ...
and
academic disciplines
An academic discipline or academic field is a subdivision of knowledge that is taught and researched at the college or university level. Disciplines are defined (in part) and recognized by the academic journals in which research is published, a ...
conceptualize it in various ways.
Philosophical questions about the nature of reality, existence, or being are considered under the
rubric
A rubric is a word or section of text that is traditionally written or printed in red ink for emphasis. The word derives from the Latin , meaning red ochre or red chalk, and originates in medieval illuminated manuscripts from the 13th century or ...
of
ontology
Ontology is the philosophical study of existence, being. It is traditionally understood as the subdiscipline of metaphysics focused on the most general features of reality. As one of the most fundamental concepts, being encompasses all of realit ...
, a major branch of
metaphysics
Metaphysics is the branch of philosophy that examines the basic structure of reality. It is traditionally seen as the study of mind-independent features of the world, but some theorists view it as an inquiry into the conceptual framework of ...
in the Western intellectual tradition. Ontological questions also feature in diverse branches of
philosophy
Philosophy ('love of wisdom' in Ancient Greek) is a systematic study of general and fundamental questions concerning topics like existence, reason, knowledge, Value (ethics and social sciences), value, mind, and language. It is a rational an ...
, including the
philosophy of science
Philosophy of science is the branch of philosophy concerned with the foundations, methods, and implications of science. Amongst its central questions are the difference between science and non-science, the reliability of scientific theories, ...
,
religion
Religion is a range of social system, social-cultural systems, including designated religious behaviour, behaviors and practices, morals, beliefs, worldviews, religious text, texts, sanctified places, prophecies, ethics in religion, ethics, or ...
,
mathematics
Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...
, and
logic
Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the study of deductively valid inferences or logical truths. It examines how conclusions follow from premises based on the structure o ...
. These include questions about whether only physical objects are real (e.g.,
physicalism
In philosophy, physicalism is the view that "everything is physical", that there is "nothing over and above" the physical, or that everything supervenience, supervenes on the physical. It is opposed to idealism, according to which the world arises ...
), whether reality is fundamentally immaterial (e.g.,
idealism
Idealism in philosophy, also known as philosophical realism or metaphysical idealism, is the set of metaphysics, metaphysical perspectives asserting that, most fundamentally, reality is equivalent to mind, Spirit (vital essence), spirit, or ...
), whether hypothetical unobservable entities posited by scientific theories exist (e.g.,
scientific realism
Scientific realism is the philosophical view that the universe described by science (including both observable and unobservable aspects) exists independently of our perceptions, and that verified scientific theories are at least approximately true ...
), whether
God
In monotheistic belief systems, God is usually viewed as the supreme being, creator, and principal object of faith. In polytheistic belief systems, a god is "a spirit or being believed to have created, or for controlling some part of the un ...
exists, whether numbers and other
abstract objects
In philosophy and the arts, a fundamental distinction exists between abstract and concrete entities. While there is no universally accepted definition, common examples illustrate the difference: numbers, sets, and ideas are typically classified ...
exist, and whether
possible world
A possible world is a complete and consistent way the world is or could have been. Possible worlds are widely used as a formal device in logic, philosophy, and linguistics in order to provide a semantics for intensional and modal logic. Their met ...
s exist.
Etymology and meaning
The word ''reality'' is a borrowing from the
Middle French
Middle French () is a historical division of the French language that covers the period from the mid-14th to the early 17th centuries. It is a period of transition during which:
* the French language became clearly distinguished from the other co ...
''realité'' and the
post-Classical Latin ''realitas''. According to the ''
Oxford English Dictionary
The ''Oxford English Dictionary'' (''OED'') is the principal historical dictionary of the English language, published by Oxford University Press (OUP), a University of Oxford publishing house. The dictionary, which published its first editio ...
'', it first appeared in English in 1513. The first definition given is "Real existence; what is real rather than imagined or desired; the aggregate of real things or existences; that which underlies and is the truth of appearances or phenomena". (A second sense, now obsolete, refers to
real property
In English common law, real property, real estate, immovable property or, solely in the US and Canada, realty, refers to parcels of land and any associated structures which are the property of a person. For a structure (also called an Land i ...
.)
Western philosophy
Philosophy addresses two different aspects of the topic of reality: the nature of reality itself, and the relationship between the
mind
The mind is that which thinks, feels, perceives, imagines, remembers, and wills. It covers the totality of mental phenomena, including both conscious processes, through which an individual is aware of external and internal circumstances ...
(as well as
language
Language is a structured system of communication that consists of grammar and vocabulary. It is the primary means by which humans convey meaning, both in spoken and signed language, signed forms, and may also be conveyed through writing syste ...
and culture) and reality.
On the one hand,
ontology
Ontology is the philosophical study of existence, being. It is traditionally understood as the subdiscipline of metaphysics focused on the most general features of reality. As one of the most fundamental concepts, being encompasses all of realit ...
is the study of being, and the central topic of the field is couched, variously, in terms of being, existence, "what is", and reality. The task in ontology is to describe the most general
categories of reality and how they are interrelated. If a philosopher wanted to proffer a positive definition of the concept "reality", it would be done under this heading. As explained above, some philosophers draw a distinction between reality and existence. In fact, many analytic philosophers today tend to avoid the term "real" and "reality" in discussing ontological issues. But for those who would treat "is real" the same way they treat "exists", one of the leading questions of
analytic philosophy
Analytic philosophy is a broad movement within Western philosophy, especially English-speaking world, anglophone philosophy, focused on analysis as a philosophical method; clarity of prose; rigor in arguments; and making use of formal logic, mat ...
has been whether existence (or reality) is a property of objects. It has been widely held by analytic philosophers that it is ''not'' a property at all, though this view has lost some ground in recent decades.
On the other hand, particularly in discussions of
objectivity that have feet in both
metaphysics
Metaphysics is the branch of philosophy that examines the basic structure of reality. It is traditionally seen as the study of mind-independent features of the world, but some theorists view it as an inquiry into the conceptual framework of ...
and epistemology, philosophical discussions of "reality" often concern the ways in which reality is, or is not, in some way ''dependent upon'' (or, to use fashionable
jargon
Jargon, or technical language, is the specialized terminology associated with a particular field or area of activity. Jargon is normally employed in a particular Context (language use), communicative context and may not be well understood outside ...
, "constructed" out of) mental and cultural factors such as perceptions, beliefs, and other mental states, as well as cultural artifacts, such as religions and
political movement
A political movement is a collective attempt by a group of people to change government policy or social values. Political movements are usually in opposition to an element of the status quo, and are often associated with a certain ideology. Some t ...
s, on up to the vague notion of a common cultural
world view
A worldview (also world-view) or is said to be the fundamental cognitive orientation of an individual or society encompassing the whole of the individual's or society's knowledge, culture, and point of view. However, when two parties view the s ...
, or .
Realism
The view that there is a reality independent of any beliefs, perceptions, etc., is called
realism. More specifically, philosophers are given to speaking about "realism ''about''" this and that, such as realism about universals or realism about the external world. Generally, where one can identify any class of object, the existence or essential characteristics of which is said not to depend on perceptions, beliefs, language, or any other human artifact, one can speak of "realism ''about''" that object.
A
correspondence theory of knowledge about what exists claims that "true" knowledge of reality represents accurate correspondence of statements about and images of reality with the actual reality that the statements or images are attempting to represent. For example, the
scientific method
The scientific method is an Empirical evidence, empirical method for acquiring knowledge that has been referred to while doing science since at least the 17th century. Historically, it was developed through the centuries from the ancient and ...
can
verify
CONFIG.SYS is the primary configuration file for the DOS and OS/2 operating systems. It is a special ASCII text file that contains user-accessible setup or configuration directives evaluated by the operating system's DOS BIOS (typically residi ...
that a statement is true based on the observable evidence that a thing exists. Many humans can point to the
Rocky Mountains
The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in great-circle distance, straight-line distance from the northernmost part of Western Can ...
and say that this
mountain range
A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have aris ...
exists, and continues to exist even if no one is observing it or making statements about it.
Anti-realism
One can also speak of ''anti''-realism about the same objects. ''Anti-realism'' is the latest in a long series of terms for views opposed to realism. Perhaps the first was
idealism
Idealism in philosophy, also known as philosophical realism or metaphysical idealism, is the set of metaphysics, metaphysical perspectives asserting that, most fundamentally, reality is equivalent to mind, Spirit (vital essence), spirit, or ...
, so called because reality was said to be in the mind, or a product of our ''ideas''.
Berkeleyan idealism is the view, propounded by the Irish
empiricist
In philosophy, empiricism is an epistemological view which holds that true knowledge or justification comes only or primarily from sensory experience and empirical evidence. It is one of several competing views within epistemology, along ...
George Berkeley
George Berkeley ( ; 12 March 168514 January 1753), known as Bishop Berkeley (Bishop of Cloyne of the Anglican Church of Ireland), was an Anglo-Irish philosopher, writer, and clergyman who is regarded as the founder of "immaterialism", a philos ...
, that the objects of perception are actually ideas in the mind. In this view, one might be tempted to say that reality is a "mental construct"; this is not quite accurate, however, since, in Berkeley's view, perceptual ideas are created and coordinated by God. By the 20th century, views similar to Berkeley's were called
phenomenalism
In metaphysics, phenomenalism is the view that physical objects cannot justifiably be said to exist as " things-in-themselves", but only as perceptual phenomena or sensory stimuli (e.g. redness, hardness, softness, sweetness, etc.) situated in t ...
. Phenomenalism differs from Berkeleyan idealism primarily in that Berkeley believed that minds, or souls, are not merely ideas nor made up of ideas, whereas varieties of phenomenalism, such as that advocated by
Russell, tended to go farther to say that the mind itself is merely a collection of perceptions, memories, etc., and that there is no mind or soul over and above such
mental event
A mental event is any event that happens within the mind of a conscious individual. Examples include thoughts, feelings, decisions, dreams, and realizations. These events often make up the conscious life that are associated with cognitive functio ...
s. Finally, anti-realism became a fashionable term for ''any'' view which held that the existence of some object depends upon the mind or cultural artifacts. The view that the so-called external world is really merely a social, or cultural, artifact, called
social constructionism
Social constructionism is a term used in sociology, social ontology, and communication theory. The term can serve somewhat different functions in each field; however, the foundation of this Conceptual framework, theoretical framework suggests ...
, is one variety of anti-realism.
Cultural relativism
Cultural relativism is the view that concepts and moral values must be understood in their own cultural context and not judged according to the standards of a different culture. It asserts the equal validity of all points of view and the relati ...
is the view that
social issues
A social issue is a problem that affects many people within a society. It is a group of common problems in present-day society that many people strive to solve. It is often the consequence of factors extending beyond an individual's control. Soc ...
such as morality are not absolute, but at least partially
cultural artifact
A cultural artifact, or cultural artefact (see American and British English spelling differences), is a term used in the social sciences, particularly anthropology, ethnology and sociology for anything created by humans which gives information ...
. Potentially the most extreme form of anti-realism is
solipsism
Solipsism ( ; ) is the philosophical idea that only one's mind is sure to exist. As an epistemological position, solipsism holds that knowledge of anything outside one's own mind is unsure; the external world and other minds cannot be known ...
— the belief that oneself is the only thing in existence.
Being
The nature of
being
Existence is the state of having being or reality in contrast to nonexistence and nonbeing. Existence is often contrasted with essence: the essence of an entity is its essential features or qualities, which can be understood even if one do ...
is a perennial topic in metaphysics. For instance,
Parmenides
Parmenides of Elea (; ; fl. late sixth or early fifth century BC) was a Pre-Socratic philosophy, pre-Socratic ancient Greece, Greek philosopher from Velia, Elea in Magna Graecia (Southern Italy).
Parmenides was born in the Greek colony of Veli ...
taught that reality was a single unchanging Being, whereas
Heraclitus
Heraclitus (; ; ) was an Ancient Greece, ancient Greek Pre-Socratic philosophy, pre-Socratic philosopher from the city of Ephesus, which was then part of the Achaemenid Empire, Persian Empire. He exerts a wide influence on Western philosophy, ...
wrote that all things flow. The 20th-century philosopher
Heidegger
Martin Heidegger (; 26 September 1889 – 26 May 1976) was a German philosopher known for contributions to phenomenology, hermeneutics, and existentialism. His work covers a range of topics including metaphysics, art, and language.
In April ...
thought previous philosophers have lost sight of the question of Being (qua Being) in favour of the questions of beings (existing things), so he believed that a return to the Parmenidean approach was needed. An
ontological catalogue is an attempt to list the fundamental constituents of reality. The question of whether or not
existence
Existence is the state of having being or reality in contrast to nonexistence and nonbeing. Existence is often contrasted with essence: the essence of an entity is its essential features or qualities, which can be understood even if one does ...
is a
predicate has been discussed since the Early Modern period, not least in relation to the
ontological argument for the existence of God. Existence, ''that'' something is, has been contrasted with ''
essence
Essence () has various meanings and uses for different thinkers and in different contexts. It is used in philosophy and theology as a designation for the property (philosophy), property or set of properties or attributes that make an entity the ...
'', the question of ''what'' something is.
Since existence without essence seems blank, it associated with
nothingness
Nothing, no-thing, or no thing is the complete absence of ''anything'', as the opposite of ''something'' and an antithesis of everything. The concept of nothing has been a matter of philosophical debate since at least the 5th century BCE. Earl ...
by philosophers such as Hegel. Existential
nihilism
Nihilism () encompasses various views that reject certain aspects of existence. There have been different nihilist positions, including the views that Existential nihilism, life is meaningless, that Moral nihilism, moral values are baseless, and ...
represents an extremely negative view of being, the
absolute
Absolute may refer to:
Companies
* Absolute Entertainment, a video game publisher
* Absolute Radio, (formerly Virgin Radio), independent national radio station in the UK
* Absolute Software Corporation, specializes in security and data risk ma ...
a positive one.
Perception
The question of
direct or "naïve" realism, as opposed to
indirect or "representational" realism, arises in the
philosophy of perception
The philosophy of perception is concerned with the nature of Perception, perceptual experience and the status of sense data, perceptual data, in particular how they relate to beliefs about, or knowledge of, the world.cf. http://plato.stanford.ed ...
and
of mind out of the debate over the nature of
conscious
Consciousness, at its simplest, is awareness of a state or object, either internal to oneself or in one's external environment. However, its nature has led to millennia of analyses, explanations, and debate among philosophers, scientists, a ...
experience
Experience refers to Consciousness, conscious events in general, more specifically to perceptions, or to the practical knowledge and familiarity that is produced by these processes. Understood as a conscious event in the widest sense, experience i ...
;
[Lehar, Steve. (2000)]
The Function of Conscious Experience: An Analogical Paradigm of Perception and Behavior
, ''Consciousness and Cognition''.[Lehar, Steve. (2000)]
, ''The Function of Conscious Experience''. the
epistemological
Epistemology is the branch of philosophy that examines the nature, origin, and limits of knowledge. Also called "the theory of knowledge", it explores different types of knowledge, such as propositional knowledge about facts, practical knowled ...
question of whether the world we see around us is the real world itself or merely an internal perceptual copy of that world generated by
neural processes in our brain.
Naïve realism
In philosophy of perception and epistemology, naïve realism (also known as direct realism, manifest realism or perceptual realism) is the idea that the senses provide us with direct awareness of objects as they really are. When referred to as ...
is known as ''direct'' realism when developed to counter ''indirect'' or representative realism, also known as
epistemological dualism, the philosophical position that our conscious experience is not of the real world itself but of an internal representation, a miniature
virtual-reality replica of the world.
Timothy Leary
Timothy Francis Leary (October 22, 1920 – May 31, 1996) was an American psychologist and author known for his strong advocacy of psychedelic drugs. Evaluations of Leary are polarized, ranging from "bold oracle" to "publicity hound". Accordin ...
coined the influential term
Reality Tunnel
Reality tunnel is a theory that, with a subconscious set of mental filters formed from beliefs and experiences, every individual interprets the same world differently, hence "Truth is in the eye of the beholder". It is similar to the idea of repr ...
, by which he means a kind of
representative realism. The theory states that, with a subconscious set of mental filters formed from their beliefs and experiences, every individual interprets the same world differently, hence "Truth is in the eye of the beholder". His ideas influenced the work of his friend
Robert Anton Wilson
Robert Anton Wilson (born Robert Edward Wilson; January 18, 1932 – January 11, 2007) was an American writer, futurist, psychologist, and self-described agnostic mystic. Recognized within Discordianism as an Episkopos, pope and saint, Wilson ...
.
Abstract objects and mathematics
The status of
abstract entities, particularly numbers, is a topic of discussion in mathematics.
In the philosophy of mathematics, the best known form of realism about numbers is
Platonic realism
The Theory of Forms or Theory of Ideas, also known as Platonic idealism or Platonic realism, is a philosophical theory credited to the Classical Greek philosopher Plato.
A major concept in metaphysics, the theory suggests that the physical w ...
, which grants them abstract, immaterial existence. Other forms of realism identify mathematics with the concrete physical universe.
Anti-realist stances include
formalism and
fictionalism.
Some approaches are selectively realistic about some mathematical objects but not others.
Finitism
Finitism is a philosophy of mathematics that accepts the existence only of finite set, finite mathematical objects. It is best understood in comparison to the mainstream philosophy of mathematics where infinite mathematical objects (e.g., infinite ...
rejects
infinite quantities.
Ultra-finitism accepts finite quantities up to a certain amount.
Constructivism and
intuitionism
In the philosophy of mathematics, intuitionism, or neointuitionism (opposed to preintuitionism), is an approach where mathematics is considered to be purely the result of the constructive mental activity of humans rather than the discovery of fu ...
are realistic about objects that can be explicitly constructed, but reject the use of the
principle of the excluded middle to prove existence by
reductio ad absurdum
In logic, (Latin for "reduction to absurdity"), also known as (Latin for "argument to absurdity") or ''apagogical argument'', is the form of argument that attempts to establish a claim by showing that the opposite scenario would lead to absur ...
.
The traditional debate has focused on whether an abstract (immaterial, intelligible) realm of numbers has existed ''in addition to'' the physical (sensible, concrete) world. A recent development is the
mathematical universe hypothesis
In physics and cosmology, the mathematical universe hypothesis (MUH), also known as the ultimate ensemble theory, is a speculative "theory of everything" (TOE) proposed by cosmologist Max Tegmark. According to the hypothesis, the universe ''is'' a ...
, the theory that ''only'' a mathematical world exists, with the finite, physical world being an illusion within it.
An extreme form of realism about mathematics is the
mathematical multiverse hypothesis advanced by
Max Tegmark
Max Erik Tegmark (born 5 May 1967) is a Swedish-American physicist, machine learning researcher and author. He is best known for his book ''Life 3.0'' about what the world might look like as artificial intelligence continues to improve. Tegmark i ...
. Tegmark's sole postulate is: ''All structures that exist mathematically also exist physically''. That is, in the sense that "in those
orldscomplex enough to contain self-aware substructures
heywill subjectively perceive themselves as existing in a physically 'real' world".
The hypothesis suggests that worlds corresponding to different sets of initial conditions, physical constants, or altogether different equations should be considered real. The theory can be considered a form of
Platonism
Platonism is the philosophy of Plato and philosophical systems closely derived from it, though contemporary Platonists do not necessarily accept all doctrines of Plato. Platonism has had a profound effect on Western thought. At the most fundam ...
in that it posits the existence of mathematical entities, but can also be considered a
mathematical monism in that it denies that anything exists except mathematical objects.
Properties
The problem of universals is an ancient problem in metaphysics about whether
universals
In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For exa ...
exist. Universals are general or abstract qualities, characteristics,
properties
Property is the ownership of land, resources, improvements or other tangible objects, or intellectual property.
Property may also refer to:
Philosophy and science
* Property (philosophy), in philosophy and logic, an abstraction characterizing an ...
, kinds or
relations, such as being male/female, solid/liquid/gas or a certain colour, that can be predicated of individuals or particulars or that individuals or particulars can be regarded as sharing or participating in. For example, Scott, Pat, and Chris have in common the universal quality of ''being human'' or ''humanity''.
The realist school claims that universals are real – they exist and are distinct from the particulars that instantiate them. There are various forms of realism. Two major forms are
Platonic realism
The Theory of Forms or Theory of Ideas, also known as Platonic idealism or Platonic realism, is a philosophical theory credited to the Classical Greek philosopher Plato.
A major concept in metaphysics, the theory suggests that the physical w ...
and
Aristotelian realism. ''Platonic realism'' is the view that universals are real entities and they exist independent of particulars. ''Aristotelian realism'', on the other hand, is the view that universals are real entities, but their existence is dependent on the particulars that exemplify them.
Nominalism
In metaphysics, nominalism is the view that universals and abstract objects do not actually exist other than being merely names or labels. There are two main versions of nominalism. One denies the existence of universals—that which can be inst ...
and
conceptualism
In metaphysics, conceptualism is a theory that explains universality of particulars as conceptualized frameworks situated within the thinking mind. Intermediate between nominalism and realism, the conceptualist view approaches the metaphysical ...
are the main forms of anti-realism about universals.
Time and space
A traditional realist position in ontology is that time and space have existence apart from the human mind.
Idealists
Idealism in philosophy, also known as philosophical realism or metaphysical idealism, is the set of metaphysical perspectives asserting that, most fundamentally, reality is equivalent to mind, spirit, or consciousness; that reality is enti ...
deny or doubt the existence of objects independent of the mind. Some
anti-realists whose ontological position is that objects outside the mind do exist, nevertheless doubt the independent existence of time and space.
Kant
Immanuel Kant (born Emanuel Kant; 22 April 1724 – 12 February 1804) was a German philosopher and one of the central Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemology, metaphysics, et ...
, in the ''
Critique of Pure Reason
The ''Critique of Pure Reason'' (; 1781; second edition 1787) is a book by the German philosopher Immanuel Kant, in which the author seeks to determine the limits and scope of metaphysics. Also referred to as Kant's "First Critique", it was foll ...
'', described time as an ''
a priori
('from the earlier') and ('from the later') are Latin phrases used in philosophy to distinguish types of knowledge, Justification (epistemology), justification, or argument by their reliance on experience. knowledge is independent from any ...
'' notion that, together with other ''a priori'' notions such as
space
Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless ...
, allows us to comprehend
sense experience. Kant denies that either space or time are
substance, entities in themselves, or learned by experience; he holds rather that both are elements of a systematic framework we use to structure our experience. Spatial
measurement
Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events.
In other words, measurement is a process of determining how large or small a physical quantity is as compared to ...
s are used to
quantify how far apart
objects are, and temporal measurements are used to quantitatively compare the interval between (or duration of)
events. Although space and time are held to be ''transcendentally ideal'' in this sense, they are also ''empirically real'', i.e. not mere illusions.
Idealist writers such as
J. M. E. McTaggart in ''
The Unreality of Time'' have argued that time is an illusion.
As well as differing about the reality of time as a whole, metaphysical theories of time can differ in their ascriptions of reality to the
past
The past is the set of all Spacetime#Definitions, events that occurred before a given point in time. The past is contrasted with and defined by the present and the future. The concept of the past is derived from the linear fashion in which human ...
, present and
future
The future is the time after the past and present. Its arrival is considered inevitable due to the existence of time and the laws of physics. Due to the apparent nature of reality and the unavoidability of the future, everything that currently ex ...
separately.
*
Presentism holds that the past and future are unreal, and only an ever-changing present is real.
* The
block universe theory, also known as Eternalism, holds that past, present and future are all real, but the passage of time is an illusion. It is often said to have a scientific basis in
relativity.
* The
growing block universe theory holds that past and present are real, but the future is not.
Time, and the related concepts of process and
evolution
Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
are central to the
system-building metaphysics of
A. N. Whitehead and
Charles Hartshorne
Charles Hartshorne (; June 5, 1897 – October 9, 2000) was an American philosopher who concentrated primarily on the philosophy of religion and metaphysics, but also contributed to ornithology. He developed the neoclassical idea of God and ...
.
Possible worlds
The term "possible world" goes back to
Leibniz's theory of possible worlds, used to analyse necessity,
possibility
Possibility is the condition or fact of being possible. Latin origins of the word hint at ability.
Possibility may refer to:
* Probability, the measure of the likelihood that an event will occur
* Epistemic possibility, a topic in philosophy ...
, and similar
modal notions.
Modal realism
Modal realism is the view propounded by the philosopher David Lewis that all possible worlds are real in the same way as is the actual world: they are "of a kind with this world of ours." It states that possible worlds exist, possible worlds are ...
is the view, notably propounded by
David Kellogg Lewis
David (; , "beloved one") was a king of ancient Israel and Judah and the third king of the United Monarchy, according to the Hebrew Bible and Old Testament.
The Tel Dan stele, an Aramaic-inscribed stone erected by a king of Aram-Dama ...
, that all
possible worlds
Possible Worlds may refer to:
* Possible worlds, concept in philosophy
* ''Possible Worlds'' (play), 1990 play by John Mighton
** ''Possible Worlds'' (film), 2000 film by Robert Lepage, based on the play
* Possible Worlds (studio)
* ''Possible ...
are as real as the actual world. In short: the actual world is regarded as merely one among an
infinite set
Set, The Set, SET or SETS may refer to:
Science, technology, and mathematics Mathematics
*Set (mathematics), a collection of elements
*Category of sets, the category whose objects and morphisms are sets and total functions, respectively
Electro ...
of
logically possible worlds, some "nearer" to the actual world and some more remote. Other theorists may use the Possible World framework to express and explore problems without committing to it ontologically. Possible world theory is related to
alethic modal logic: a proposition is ''necessary'' if it is true in all possible worlds, and ''possible'' if it is true in at least one. The
many worlds interpretation of quantum mechanics is a similar idea in science.
Theories of everything (TOE) and philosophy
The philosophical implications of a physical TOE are frequently debated. For example, if philosophical
physicalism
In philosophy, physicalism is the view that "everything is physical", that there is "nothing over and above" the physical, or that everything supervenience, supervenes on the physical. It is opposed to idealism, according to which the world arises ...
is true, a physical TOE will coincide with a philosophical theory of everything.
The
"system building" style of metaphysics attempts to answer ''all'' the important questions in a coherent way, providing a complete picture of the world.
Plato
Plato ( ; Greek language, Greek: , ; born BC, died 348/347 BC) was an ancient Greek philosopher of the Classical Greece, Classical period who is considered a foundational thinker in Western philosophy and an innovator of the writte ...
and
Aristotle
Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...
could be said to be early examples of comprehensive systems. In the early modern period (17th and 18th centuries), the system-building ''scope'' of philosophy is often linked to the rationalist ''method'' of philosophy, that is the technique of deducing the nature of the world by pure ''a priori'' reason. Examples from the early modern period include the
Leibniz
Gottfried Wilhelm Leibniz (or Leibnitz; – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat who is credited, alongside Sir Isaac Newton, with the creation of calculus in addition to many ...
's
Monadology
The ''Monadology'' (, 1714) is one of Gottfried Leibniz's best known works of his later philosophy. It is a short text which presents, in some 90 paragraphs, a metaphysics of simple substances, or '' monads''.
Text
During his last stay in V ...
,
Descartes's
Dualism
Dualism most commonly refers to:
* Mind–body dualism, a philosophical view which holds that mental phenomena are, at least in certain respects, not physical phenomena, or that the mind and the body are distinct and separable from one another
* P ...
,
Spinoza
Baruch (de) Spinoza (24 November 163221 February 1677), also known under his Latinized pen name Benedictus de Spinoza, was a philosopher of Portuguese-Jewish origin, who was born in the Dutch Republic. A forerunner of the Age of Enlightenmen ...
's
Monism
Monism attributes oneness or singleness () to a concept, such as to existence. Various kinds of monism can be distinguished:
* Priority monism states that all existing things go back to a source that is distinct from them; e.g., in Neoplatonis ...
.
Hegel
Georg Wilhelm Friedrich Hegel (27 August 1770 – 14 November 1831) was a 19th-century German idealism, German idealist. His influence extends across a wide range of topics from metaphysical issues in epistemology and ontology, to political phi ...
's
Absolute idealism
Absolute idealism is chiefly associated with Friedrich Schelling and G. W. F. Hegel, both of whom were German idealist philosophers in the 19th century. The label has also been attached to others such as Josiah Royce, an American philosopher wh ...
and
Whitehead's
Process philosophy
Process philosophy (also ontology of becoming or processism) is an approach in philosophy that identifies processes, changes, or shifting relationships as the only real experience of everyday living. In opposition to the classical view of change ...
were later systems.
Other philosophers do not believe its techniques can aim so high. Some scientists think a more mathematical approach than philosophy is needed for a TOE, for instance
Stephen Hawking
Stephen William Hawking (8January 194214March 2018) was an English theoretical physics, theoretical physicist, cosmologist, and author who was director of research at the Centre for Theoretical Cosmology at the University of Cambridge. Between ...
wrote in ''
A Brief History of Time
''A Brief History of Time: From the Big Bang to Black Holes'' is a book on cosmology by the physicist Stephen Hawking, first published in 1988.
Hawking writes in non-technical terms about the structure, origin, development and eventual fate of ...
'' that even if we had a TOE, it would necessarily be a set of equations. He wrote, "What is it that breathes fire into the equations and makes a universe for them to describe?"
Phenomenology
On a much broader and more subjective level, private experiences, curiosity, inquiry, and the selectivity involved in personal interpretation of events shapes reality as seen by one and only one person and hence is called
phenomenological. While this
form of reality might be common to others as well, it could at times also be so unique to oneself as to never be experienced or agreed upon by anyone else. Much of the kind of experience deemed
spiritual occurs on this level of reality.
Phenomenology is a
philosophical method developed in the early years of the twentieth century by
Edmund Husserl
Edmund Gustav Albrecht Husserl (; 8 April 1859 – 27 April 1938) was an Austrian-German philosopher and mathematician who established the school of Phenomenology (philosophy), phenomenology.
In his early work, he elaborated critiques of histori ...
(1859–1938) and a circle of followers at the universities of
Göttingen
Göttingen (, ; ; ) is a college town, university city in Lower Saxony, central Germany, the Capital (political), capital of Göttingen (district), the eponymous district. The River Leine runs through it. According to the 2022 German census, t ...
and
Munich
Munich is the capital and most populous city of Bavaria, Germany. As of 30 November 2024, its population was 1,604,384, making it the third-largest city in Germany after Berlin and Hamburg. Munich is the largest city in Germany that is no ...
in Germany. Subsequently, phenomenological themes were taken up by philosophers in France, the United States, and elsewhere, often in contexts far removed from Husserl's work.
The word ''phenomenology'' comes from the
Greek
Greek may refer to:
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group
*Greek language, a branch of the Indo-European language family
**Proto-Greek language, the assumed last common ancestor of all kno ...
''phainómenon'', meaning "that which appears", and ''lógos'', meaning "study". In Husserl's conception, phenomenology is primarily concerned with making the structures of consciousness, and the
phenomena
A phenomenon ( phenomena), sometimes spelled phaenomenon, is an observable Event (philosophy), event. The term came into its modern Philosophy, philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be ...
which appear in acts of consciousness, objects of systematic reflection and analysis. Such reflection was to take place from a highly modified "
first person" viewpoint, studying phenomena not as they appear to "my" consciousness, but to any consciousness whatsoever. Husserl believed that phenomenology could thus provide a firm basis for all human
knowledge
Knowledge is an Declarative knowledge, awareness of facts, a Knowledge by acquaintance, familiarity with individuals and situations, or a Procedural knowledge, practical skill. Knowledge of facts, also called propositional knowledge, is oft ...
, including
scientific knowledge
Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...
, and could establish philosophy as a "rigorous science".
Husserl's conception of phenomenology has been criticised and developed by his student and assistant
Martin Heidegger
Martin Heidegger (; 26 September 1889 – 26 May 1976) was a German philosopher known for contributions to Phenomenology (philosophy), phenomenology, hermeneutics, and existentialism. His work covers a range of topics including metaphysics, art ...
(1889–1976), by
existentialists
Existentialism is a family of philosophy, philosophical views and inquiry that explore the human individual's struggle to lead an Authenticity (philosophy), authentic life despite the apparent Absurdity#The Absurd, absurdity or incomprehensibili ...
like
Maurice Merleau-Ponty
Maurice Jean Jacques Merleau-Ponty. ( ; ; 14 March 1908 – 3 May 1961) was a French phenomenological philosopher, strongly influenced by Edmund Husserl and Martin Heidegger. The constitution of meaning in human experience was his main interes ...
(1908–1961) and
Jean-Paul Sartre
Jean-Paul Charles Aymard Sartre (, ; ; 21 June 1905 – 15 April 1980) was a French philosopher, playwright, novelist, screenwriter, political activist, biographer, and literary criticism, literary critic, considered a leading figure in 20th ...
(1905–1980), and by other philosophers, such as
Paul Ricoeur (1913–2005),
Emmanuel Levinas
Emmanuel Levinas (born Emanuelis Levinas ; ; 12 January 1906 – 25 December 1995) was a French philosopher of Lithuanian Jewish ancestry who is known for his work within Jewish philosophy, existentialism, and phenomenology, focusing on the rel ...
(1906–1995), and
Dietrich von Hildebrand (1889–1977).
Skeptical hypotheses
Skeptical hypotheses in philosophy suggest that reality could be very different from what we think it is; or at least that we cannot prove it is not. Examples include:
* The "
Brain in a vat
In philosophy, the brain in a vat (BIV) is a scenario used in a variety of thought experiments intended to draw out certain features of human conceptions of knowledge, reality, truth, mind, consciousness, and Meaning (philosophy of language), m ...
" hypothesis is cast in scientific terms. It supposes that one might be a disembodied brain kept alive in a vat, and fed false sensory signals. This hypothesis is related to the Matrix hypothesis below.
* The "
Dream argument
The dream argument is the postulation that the act of dreaming provides preliminary evidence that the senses we trust to distinguish reality from illusion should not be fully trusted, and therefore, any state that is dependent on our senses sho ...
" of Descartes and
Zhuangzi supposes reality to be indistinguishable from a dream.
* Descartes'
Evil demon
The evil demon, also known as ''Deus deceptor'', malicious demon, and evil genius, is an epistemological concept that features prominently in Cartesian philosophy. In the first of his 1641 ''Meditations on First Philosophy'', Descartes imag ...
is a being "as clever and deceitful as he is powerful, who has directed his entire effort to misleading me."
* The
five minute hypothesis (or
omphalos hypothesis or
Last Thursdayism) suggests that the world was created recently together with records and traces indicating a greater age.
* Diminished reality refers to artificially diminished reality, not due to limitations of sensory systems but via artificial
filters
Filtration is a physical process that separates solid matter and fluid from a mixture.
Filter, filtering, filters or filtration may also refer to:
Science and technology
Computing
* Filter (higher-order function), in functional programming
* Fil ...
.
*
The Matrix
''The Matrix'' is a 1999 science fiction film, science fiction action film written and directed by the Wachowskis. It is the first installment in the The Matrix (franchise), ''Matrix'' film series, starring Keanu Reeves, Laurence Fishburne, Ca ...
hypothesis or
Simulated reality hypothesis suggest that we might be inside a
computer simulation
Computer simulation is the running of a mathematical model on a computer, the model being designed to represent the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be determin ...
or
virtual reality
Virtual reality (VR) is a Simulation, simulated experience that employs 3D near-eye displays and pose tracking to give the user an immersive feel of a virtual world. Applications of virtual reality include entertainment (particularly video gam ...
. Related hypotheses may also involve simulations with signals that allow the inhabitant species in virtual or simulated reality to perceive the external reality.
Non-western philosophy
Hindu philosophy
Hindu philosophy
Hindu philosophy or Vedic philosophy is the set of philosophical systems that developed in tandem with the first Hinduism, Hindu religious traditions during the Iron Age in India, iron and Classical India, classical ages of India. In Indian ...
, particularly the
Vedic tradition, includes a number of subtly different and nuanced perspectives about the nature of reality and
unified consciousness
They are as follows (order irrelevant):
#
Advaita – non-dualism
#
Tattvavada
Dvaita Vedanta (); (originally known as Tattvavada; IAST: ''Tattvavāda''), is a sub-school in the Vedanta tradition of Hindu philosophy. The term Tattvavada literally means "arguments from a realist viewpoint". The Tattvavada (Dvaita) Veda ...
(
Dvaita
Dvaita Vedanta (); (originally known as Tattvavada; IAST: ''Tattvavāda''), is a sub-school in the Vedanta
''Vedanta'' (; , ), also known as ''Uttara Mīmāṃsā'', is one of the six orthodox (Āstika and nāstika, ''āstika'') trad ...
) – dualism
#
Dvaitadvaita
Dvaitadvaita Vedanta, also known as Svabhavika Bhedabheda and as Svabhavika Bhinnabhinna,() is the philosophical doctrine of "natural identity-in-difference" or "natural difference cum-non-difference." It was propagated by the medieval Vedānta ...
– dualistic non-dualism
#
Bhedabheda
Bhedābheda is more a tradition than a sub-school of Vedānta, which teaches that the individual self (''jīvātman'') is both different and not different from the ultimate reality known as Brahman.
Etymology
''Bhedābheda'' (Devanagari: ) is ...
– difference and non-difference
#
Vishishtadvaita
Vishishtadvaita (IAST '; ) is a school of Hindu philosophy belonging to the Vedanta tradition. Vedanta refers to the profound interpretation of the Vedas based on Prasthanatrayi. Vishishta Advaita, meaning "non-duality with distinctions", is a ...
– qualified non-dualism
#
Suddhadvaita – pure non-dualism
#
Achintya-Bheda-Abheda – inconceivable difference and non-difference
#
Dvaitadvaita Vedanta - natural identity-in-difference
#
Akshar Purushottam Darshan - multiple eternal realities
Jain philosophy
Jain philosophy
Jain philosophy or Jaina philosophy refers to the Ancient India, ancient Indian Indian philosophy, philosophical system of the Jainism, Jain religion. It comprises all the Philosophy, philosophical investigations and systems of inquiry that dev ...
postulates that seven tattva (truths or fundamental principles) constitute reality. These seven ''tattva'' are:
# ''
Jīva'' – The
soul
The soul is the purported Mind–body dualism, immaterial aspect or essence of a Outline of life forms, living being. It is typically believed to be Immortality, immortal and to exist apart from the material world. The three main theories that ...
which is characterized by consciousness.
# ''
Ajīva
''Ajiva'' (Sanskrit) is anything that has no soul or life, the polar opposite of " jīva" (soul). Because ''ajiva'' has no life, it does not accumulate ''karma'' and cannot die. Examples of ajiva include chairs, computers, paper, plastic, etc. ...
'' – The non-soul.
# ''
Asrava
''Asrava'' (''āsrava'' "influx") is one of the ''tattva'' or the fundamental reality of the world as per the Jain philosophy. It refers to the influence of body and mind causing the soul to generate karma.
The karmic process in Jainism is b ...
'' – Influx of
karma
Karma (, from , ; ) is an ancient Indian concept that refers to an action, work, or deed, and its effect or consequences. In Indian religions, the term more specifically refers to a principle of cause and effect, often descriptively called ...
.
# ''
Bandha'' – The bondage of karma.
# ''
Samvara
''Samvara'' (''saṃvara'') is one of the '' tattva'' or the fundamental reality of the world as per the Jain philosophy. It means stoppage—the stoppage of the influx of the material karmas into the soul consciousness. The karmic process in ...
'' – Obstruction of the inflow of karmic matter into the soul.
# ''
Nirjara
''Nirjara'' is one of the seven fundamental principles, or Tattva in Jain philosophy, and refers to the shedding or removal of accumulated karmas from the atma (soul), essential for breaking free from samsara, the cycle of birth-death and r ...
'' – Shedding of karmas.
# ''
Moksha
''Moksha'' (; , '), also called ''vimoksha'', ''vimukti'', and ''mukti'', is a term in Jainism, Buddhism, Hinduism, and Sikhism for various forms of emancipation, liberation, '' nirvana'', or release. In its soteriological and eschatologic ...
'' – Liberation or Salvation, i.e. the complete annihilation of all karmic matter (bound with any particular soul).
Physical sciences
Scientific realism
Scientific realism
Scientific realism is the philosophical view that the universe described by science (including both observable and unobservable aspects) exists independently of our perceptions, and that verified scientific theories are at least approximately true ...
is, at the most general level, the view that the world (the universe) described by science (perhaps ideal science) is the real world, as it is, independent of what we might take it to be. Within
philosophy of science
Philosophy of science is the branch of philosophy concerned with the foundations, methods, and implications of science. Amongst its central questions are the difference between science and non-science, the reliability of scientific theories, ...
, it is often framed as an answer to the question "how is the success of science to be explained?" The debate over what the success of science involves centers primarily on the status of entities that are
not directly observable discussed by
scientific theories. Generally, those who are scientific realists state that one can make reliable claims about these entities (viz., that they have the same
ontological
Ontology is the philosophical study of being. It is traditionally understood as the subdiscipline of metaphysics focused on the most general features of reality. As one of the most fundamental concepts, being encompasses all of reality and every ...
status) as directly observable entities, as opposed to
instrumentalism
In philosophy of science and in epistemology, instrumentalism is a methodological view that ideas are useful instruments, and that the worth of an idea is based on how effective it is in explaining and predicting natural phenomena.
According to in ...
. The most used and studied scientific theories today state more or less the truth.
Realism and locality in physics
''Realism'' in the sense used by physicists does not equate to
realism in metaphysics. The latter is the claim that the world is mind-independent: that even if the results of a measurement do not pre-exist the act of measurement, that does not require that they are the creation of the observer. Furthermore, a mind-independent property does not have to be the value of some physical variable such as position or
momentum
In Newtonian mechanics, momentum (: momenta or momentums; more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. ...
. A property can be ''
disposition
A disposition is a quality of character, a habit, a preparation, a state of readiness, or a tendency to act in a specified way.
The terms dispositional belief and occurrent belief refer, in the former case, to a belief that is held in the mind b ...
al'' (or potential), i.e. it can be a tendency: in the way that glass objects tend to break, or are disposed to break, even if they do not ''actually'' break. Likewise, the mind-independent properties of quantum systems could consist of a tendency to respond to particular measurements with particular values with ascertainable probability. Such an ontology would be metaphysically realistic, without being realistic in the physicist's sense of "local realism" (which would require that a single value be produced with certainty).
A closely related term is
counterfactual definiteness (CFD), used to refer to the claim that one can meaningfully speak of the definiteness of results of measurements that have not been performed (i.e. the ability to assume the existence of objects, and properties of objects, even when they have not been measured).
Local realism
In physics, the principle of locality states that an object is influenced directly only by its immediate surroundings. A theory that includes the principle of locality is said to be a "local theory". This is an alternative to the concept of ins ...
is a significant feature of classical mechanics, of
general relativity
General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the differential geometry, geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of grav ...
, and of classical
electrodynamics
In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...
; but not
quantum mechanics
Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ...
. In a work now called the
EPR paradox
EPR may refer to:
Science and technology
* EPR (nuclear reactor), European Pressurised-Water Reactor
* EPR paradox (Einstein–Podolsky–Rosen paradox), in physics
* Earth potential rise, in electrical engineering
* East Pacific Rise, a mid-ocea ...
, Einstein relied on local realism to suggest that
hidden variables were missing in quantum mechanics. However,
John S. Bell
John Stewart Bell (28 July 1928 – 1 October 1990) was a physicist from Northern Ireland and the originator of Bell's theorem, an important theorem in quantum physics regarding hidden-variable theories.
In 2022, the Nobel Prize in Physics ...
subsequently showed that the predictions of quantum mechanics are inconsistent with hidden variables, a result known as Bell's theorem. The predictions of quantum mechanics have been verified: Bell's inequalities are violated. This means either particles have no definite positions independent of observation (no realism) ''or'' distant measurements can affect each other (no locality) or both. Different interpretation of quantum mechanics, interpretations of quantum mechanics violate different parts of local realism.
The transition from "possible" to "actual" is a major topic of quantum physics, with related theories including quantum darwinism.
Role of "observation" in quantum mechanics
The quantum mind–body problem refers to the philosophical discussions of the mind–body problem in the context of quantum mechanics. Since quantum mechanics involves quantum superpositions, which Measurement in quantum mechanics, are not perceived by observers, some interpretations of quantum mechanics place conscious observers in a special position.
The founders of quantum mechanics debated the role of the observer, and of them, Wolfgang Pauli and Werner Heisenberg believed that quantum mechanics expressed the observers knowledge and when an experiment was completed the additional knowledge should be incorporated in the wave function, an effect that came to be called state reduction or wave function collapse, collapse. This point of view, which was never fully endorsed by Niels Bohr, was denounced as mystical and anti-scientific by Albert Einstein. Pauli accepted the term, and described quantum mechanics as ''lucid mysticism''.
Heisenberg and Bohr always described quantum mechanics in logical positivism, logical positivist terms. Bohr also took an active interest in the philosophical implications of quantum theories such as his Complementarity (physics), complementarity, for example. He believed quantum theory offers a complete description of nature, albeit one that is simply ill-suited for everyday experiences – which are better described by classical mechanics and probability. Bohr famously avoided any characterization of "reality".
Eugene Wigner reformulated the "Schrödinger's cat" thought experiment as "Wigner's friend" and proposed that the consciousness of an observer is the demarcation line which precipitates collapse of the wave function, independent of any realist interpretation. Commonly known as "consciousness causes collapse", this controversial interpretation of quantum mechanics states that observation by a conscious observer is what makes the wave function collapse. However, this is a minority view among quantum philosophers, considering it a misunderstanding. There are other possible solutions to the "Wigner's friend" thought experiment, which do not require consciousness to be different from other physical processes. Moreover, Wigner shifted to those interpretations in his later years.
[Michael Esfeld, (1999)]
Essay Review: Wigner's View of Physical Reality
, published in Studies in History and Philosophy of Modern Physics, 30B, pp. 145–154, Elsevier Science Limited.
Multiverse
The multiverse is the hypothetical set of multiple possible universes (including the historical universe we consistently experience) that together comprise everything that exists: the entirety of
space
Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless ...
, time, matter, and energy as well as the physical laws and physical constant, constants that describe them. The term was coined in 1895 by the American philosopher and psychologist William James. In the many-worlds interpretation (MWI), one of the mainstream interpretations of quantum mechanics, there are an infinite number of universes and every possible quantum outcome occurs in at least one universe, albeit there is Many-worlds interpretation#Debate whether the other worlds are real, a debate as to how real the (other) worlds are.
The structure of the multiverse, the nature of each universe within it and the relationship between the various constituent universes, depend on the specific multiverse hypothesis considered. Multiverses have been hypothesized in cosmology, physics, astronomy, religion, philosophy, transpersonal psychology and fiction, particularly in science fiction and fantasy. In these contexts, parallel universes are also called "alternative universes", "quantum universes", "interpenetrating dimensions", "parallel dimensions", "parallel worlds", "alternative realities", "alternative timelines", and "dimensional planes", among others.
Cyclic theories
Some cyclic theories postulate continuous expansion of the universe across cycles to ensure entropy growth, but they have been shown not be truly cyclic in time. In any case these types of scientific hypotheses do not fundamentally alter concepts of the ultimate origin of reality such as the cosmological argument. A theist can argue for perpetual divine creation or for an unmoved mover responsible for the first universe in the sequence.
Anthropic principle
Personal and collective reality

Each individual has a different Point of view (philosophy), view of reality, with different memories and personal history, knowledge, personality traits and experience. This system, mostly referring to the human brain, affects cognition and behavior and into this complex new knowledge integration, knowledge, memories, information, thoughts and experiences are continuously integrated. The connectome – Neuron#Connectivity, neural networks/wirings in brains – is thought to be a key factor in human variability in terms of cognition or the way we perceive the world (as a context) and related features or processes. Sensemaking is the process by which people give Semantics, meaning to their experiences and make sense of the world they live in. Personal identity is relating to questions like how a unique individual is persisting through time.
Sensemaking and determination of reality also occurs collectively, which is investigated in social epistemology and related approaches. From the collective intelligence perspective, the intelligence of the individual human (and potentially AI entities) is substantially limited and advanced intelligence emerges when multiple entities collaborate over time. Collective memory is an important component of the social construction of reality and communication and communication-related systems, such as media systems, may also be major components .
Philosophy of perception raises questions based on the evolutionary history of humans' perceptual apparatuses, particularly or especially individuals' human senses, physiological senses, described as "[w]e don't see reality—we only see what was useful to see in the past", partly suggesting that "[o]ur species has been so successful not in spite of our inability to see reality but because of it".
Scientific theories of everything
A theory of everything (TOE) is a putative theory of theoretical physics that fully explains and links together all known physical phenomena, and predicts the outcome of ''any'' experiment that could be carried out ''in principle''. The theory of everything is also called the final theory. Many candidate theories of everything have been proposed by theoretical physicists during the twentieth century, but none have been confirmed experimentally. The primary problem in producing a TOE is that
general relativity
General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the differential geometry, geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of grav ...
and quantum mechanics are hard to unify. This is one of the unsolved problems in physics.
Initially, the term "theory of everything" was used with an ironic connotation to refer to various overgeneralized theories. For example, a great-grandfather of Ijon Tichy, a character from a cycle of Stanisław Lem's science fiction stories of the 1960s, was known to work on the "General Theory of Everything". Physicist John Ellis (physicist, born 1946), John Ellis claims to have introduced the term into the technical literature in an article in ''Nature (magazine), Nature'' in 1986. Over time, the term stuck in popularizations of quantum physics to describe a theory that would unify or explain through a single model the theories of all fundamental interactions and of all particles of nature: general relativity for gravitation, and the Standard Model, standard model of elementary particle physics – which includes quantum mechanics – for electromagnetism, the two nuclear interactions, and the known elementary particles.
Current candidates for a theory of everything include string theory, M theory, and loop quantum gravity.
Technology
Media
Media – such as news media, social media, websites including Wikipedia, and fiction
– shape individuals' and society's perception of reality (including as part of belief and attitude formation)
and are partly used intentionally as means to Learning, learn about reality. Various technologies have changed society's relationship with reality such as the advent of radio and TV technologies.
Research investigates interrelations and effects, for example aspects in the social construction of reality. A major component of this shaping and representation of perceived reality is Agenda-setting theory, agenda, selection and prioritization – not only (or primarily) the quality, tone and types of content – which influences, for instance, the public agenda. Disproportional news attention for low-probability incidents – such as high-consequence accidents – can distort audiences' risk perceptions with harmful consequences. Various biases such as false balance, public attention dependence reactions like sensationalism and domination by "current events", as well as various interest-driven uses of media such as marketing can also have major impacts on the perception of reality. Time-use research, Time-use studies found that e.g. in 2018 the average U.S. American "spent around eleven hours every day looking at screens".
Virtual reality and cyberspace
Virtual reality (VR) is a Computer simulation, computer-simulated environment that can simulate physical presence in places in the real world, as well as in imaginary worlds.

The virtuality continuum is a continuous scale ranging between the completely virtual, a virtuality, and the completely real: reality. The reality–virtuality continuum therefore encompasses all possible variations and compositions of real and Virtuality, virtual objects. It has been described as a concept in new media and computer science, but in fact it could be considered a matter of anthropology. The concept was first introduced by Paul Milgram.
The area between the two extremes, where both the real and the virtual are mixed, is the so-called mixed reality. This in turn is said to consist of both augmented reality, where the virtual augments the real, and augmented virtuality, where the real augments the virtual.
Cyberspace, the world's computer systems considered as an interconnected whole, can be thought of as a virtual reality; for instance, it is portrayed as such in the cyberpunk fiction of William Gibson and others. ''Second Life'' and MMORPGs such as ''World of Warcraft'' are examples of artificial environments or virtual worlds (falling some way short of full virtual reality) in cyberspace.
"RL" in internet culture
On the Internet, "real life" refers to life in the real world. It generally references Conditio humana, life or consensus reality, in contrast to an environment seen as fiction or fantasy, such as virtual reality, lifelike experience, dreams, novels, or movies. Online, the acronym "IRL" stands for "in real life", with the meaning "not on the Internet". Sociologists engaged in the study of the Internet have determined that someday, a distinction between online and real-life worlds may seem "quaint", noting that certain types of online activity, such as sexual intrigues, have already made a full transition to complete legitimacy and "reality".
The abbreviation "RL" stands for "real life". For example, one can speak of "meeting in RL" someone whom one has met in a online chat, chat or on an Internet forum. It may also be used to express an inability to use the Internet for a time due to "RL problems". A related abbreviation is "AFK", which stands for "away from keyboard" , signifying that one is (at least temporarily) choosing to disengage themselves from the virtual world so as to focus preferentially on the real one.
World views
A common colloquial usage would have ''reality'' mean "perceptions, beliefs, and attitudes toward reality", as in "My reality is not your reality." This is often used just as a colloquialism indicating that the parties to a conversation agree, or should agree, not to quibble over deeply different conceptions of what is real. For example, in a religious discussion between friends, one might say (attempting humor), "You might disagree, but in my reality, everyone goes to heaven."
Reality can be defined in a way that links it to worldviews or parts of them (conceptual frameworks): Reality is the totality of all things, structures (actual and conceptual), events (past and present) and phenomena, whether observable or not. It is what a world view (whether it be based on individual or shared human experience) ultimately attempts to describe or map.
Certain ideas from physics, philosophy, sociology, literary criticism, and other fields shape various theories of reality. One such theory is that there simply and literally ''is'' no reality beyond the perceptions or beliefs we each have about reality.
Such attitudes are summarized in popular statements, such as "Perception is reality" or "Life is how you perceive reality" or "reality is what you can get away with" (
Robert Anton Wilson
Robert Anton Wilson (born Robert Edward Wilson; January 18, 1932 – January 11, 2007) was an American writer, futurist, psychologist, and self-described agnostic mystic. Recognized within Discordianism as an Episkopos, pope and saint, Wilson ...
), and they indicate anti-realism – that is, the view that there is no objective reality, whether acknowledged explicitly or not.
Many of the concepts of science and philosophy are often defined culture, culturally and sociology, socially. This idea was elaborated by Thomas Kuhn in his book ''The Structure of Scientific Revolutions'' (1962). ''The Social Construction of Reality'', a book about the sociology of knowledge written by Peter L. Berger and Thomas Luckmann, was published in 1966. It explained how knowledge is acquired and used for the comprehension of reality. Out of all the realities, the reality of everyday life is the most important one since our consciousness requires us to be completely aware and attentive to the experience of everyday life.
See also
* Alternate history
* Consciousness
* Extended modal realism
* Fact
* Hyperreality
*
Modal realism
Modal realism is the view propounded by the philosopher David Lewis that all possible worlds are real in the same way as is the actual world: they are "of a kind with this world of ours." It states that possible worlds exist, possible worlds are ...
* Potentiality and actuality
References
External links
*
C.D. Broad on RealityPhenomenology Online: Materials discussing and exemplifying phenomenological research
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Reality,
Concepts in metaphysics
Concepts in epistemology
Concepts in logic
Concepts in metaphilosophy
Concepts in the philosophy of language
Concepts in the philosophy of science
Ontology
Philosophy of mathematics
Philosophy of religion
Philosophy of technology
Concepts in the philosophy of mind
Concepts in social philosophy
Realism
Quantum measurement