Mereological universalism holds that any collection of entities constitutes a whole, even if the entities are otherwise unrelated. Various theories of the mereological principles underlying composition have been proposed. For example, David Lewis’s modal realism asserts that there exist countless spatiotemporally unified possible worlds, each just as real as the actual world. A different view suggests that reality is made up of many worlds that exist in parallel to one another, each representing a distinct way of how things could have been. In a narrow sense, being contrasts with becoming, and denotes stable or permanent aspects of reality. Some philosophers, such as Alexius Meinong, hold that being is a broader concept than reality, encompassing nonexistent objects, such as merely possible or incomplete objects, in addition to real or actual ones.
In the broadest sense, being is the most general category that applies to everything and contrasts only with nothingness. The term reality overlaps with various related concepts, such as being, existence, world, actuality, and truth. This view contrasts being real with being fake, like the distinction between a real duck and a fake one used as a decoy.

• Some interpretations of quantum mechanics hold that measurement outcomes are inherently probabilistic, thereby rejecting causal determinism, but this is not true for all interpretations.g
• A different view suggests that reality is made up of many worlds that exist in parallel to one another, each representing a distinct way of how things could have been.
• It is often contrasted with essence, which denotes the nature or characteristic features of an entity.
• Nominalism, another anti-realist view, rejects both mental and non-mental interpretations of universals.
• Non-reductive physicalists hold that everything is ultimately physical while insisting that higher-level psychological facts cannot be reduced to fundamental physics.
• Platonism about universals holds that they are part of reality in their own right, independent of the particular entities that instantiate them.

Levels of reality

• In the social sciences, critical realism holds that observable events in the social world only partially disclose reality.
• The widely accepted Big Bang theory holds that the universe began about 13.8 billion years ago, initially in an extremely hot, dense state, expanding and cooling ever since.
• Memory is the capacity to store information from other sources and make it available to cognitive processes when needed.
• Discussed in ancient Greek philosophy as the Eleatic principle, it states that to be real is to be able to produce changes and to be affected by them.
• Some doctrines hold that God constitutes the most fundamental level of reality as the divine origin of all creation.
• For example, emotivism holds that value statements express emotional attitudes of subjective approval or disapproval rather than objective facts.

Monism and pluralism are families of views about the roles of unity and multiplicity in the structure of reality. According to this view, even a complete understanding of physics would not render sciences dedicated to higher levels, such as psychology, obsolete. Non-reductive physicalists hold that everything is ultimately physical while insisting that higher-level psychological facts cannot be reduced to fundamental physics. In this sense, there can be matter without biological life, whereas life is built upon matter and depends on it. Lower levels, by contrast, operate according to more basic mechanisms and are prior to the higher ones.
It holds that this practice can be useful in some contexts without ascribing substantive or framework-independent reality to such entities. Relativism, another form of anti-realism, holds that what counts as real varies based on one’s perspective or conceptual framework. Phenomenalism, a related view, reduces physical objects to collections of actual or possible sensory experiences. In the broadest sense, realism is the view that the external world and its constituents exist as they do regardless of how people perceive or think about them.

Realism and anti-realism

Accordingly, worldviews address not only theoretical matters but also practical and evaluative outlooks about what matters and how one should act. Another view maintains that they are real as digital objects with genuine existence and causal powers, residing within and being constituted by computational processes. Similarly, virtual reality worlds may incorporate real-world objects into the simulation or be entirely virtual.l Although it is not a widely accepted position, various thought experiments undermining the reliability of human cognitive faculties are discussed in the academic literature. It denies the existence of knowledge in any form or domain, arguing that knowledge is impossible. These limitations indicate a gap whereby reality is not fully captured and exceeds knowledge.

Levels of reality

While some skeptical scenarios use the idea of a simulated reality to challenge the reliability of human cognition, contemporary technologies such as augmented reality and virtual reality can also inform experience. Moral skepticism is the view that there is no moral knowledge, for instance, that one cannot know whether a given behavior is morally right or wrong. Some forms target specific domains of knowledge, such as religious skepticism, which denies that beliefs about God or other religious doctrines amount to knowledge. Philosophers examine various limitations of knowledge or obstacles to the cognitive contact with reality. Philosophers discuss various sources of knowledge as ways of how this cognitive contact is established, including perception, introspection, reason, memory, and testimony.
In this sense, it is the state of being real or what all real entities have in common, separating them from unreal or illusory ones. In a slightly different sense, reality is not the totality itself but an aspect shared by all its constituents. Contemporary technology in the form of augmented and virtual reality can inform experience and raises questions about the ontological status of virtual objects. Other discussions examine space and time as frameworks that organize relations among entities, and laws of nature describing regularities or general patterns of how entities interact and changes unfold. Various criteria for distinguishing real from unreal entities have been proposed, including causal powers, mind-independence, and being non-illusory. It is often contrasted with appearance, opposing what is with what seems to be, although the accuracy and fundamentality of this contrast are disputed.
For example, psychologism asserts that mathematical objects are mental constructions or ideas rather than abstract objects. Fictionalists argue that discourse about abstract objects concerns fictional entities within make-believe frameworks. According to conceptualism, universals exist in the mind as concepts through which people categorize and order their impressions, acting as tools of cognitive organization rather than properties of external entities. Platonism about universals holds that they are part of reality in their own right, independent of the particular entities that instantiate them.

Realism and anti-realism

On this view, higher levels show greater complexity and new phenomena but depend on the lower ones and could not exist without them. Some philosophical approaches rely on the idea of fundamentality and dependence to analyze the world in terms of levels or layers, such as material, biological, psychological, and social reality. In the Hindu tradition, it is often identified with Brahman as the all-pervasive reality and the supreme principle grounding all being. Some outlooks suggest that only the fundamental level is ultimately real, arguing that non-fundamental entities are in some sense eliminable since reality can be described without them.
It characterizes realism as the view that the truth or meaning of sentences is determined by external standards or mind-independent reality. A semantic approach to the debate between realism and anti-realism, proposed by Michael Dummett, argues that the underlying disagreement concerns the meaning of statements rather than the existence of entities. On this view, reality is made up of countless concrete worlds existing in parallel without interacting with one another. In the social sciences, critical realism holds that observable events in the social world only partially disclose reality. Local realism is a view that combines the principle of locality with the notion that there are definite physical properties, whether or not they are being observed by someone.

In a broad sense, appearances are not limited to what people perceive but can also include memories, beliefs, and thoughts. Unreal entities, by contrast, depend for their existence on thoughts and ideas; they would not arise or would vanish without the mental activity creating or sustaining them. A related topic concerns the possibility and limits of knowledge as a successful cognitive contact with reality. Anti-realism, by contrast, holds that certain aspects of reality depend on mental processes, subjective perspectives, or social conventions.
It comprises beliefs, ideas, and attitudes that form a background against which people interpret experiences, make decisions, and navigate life. By contrast, Arthur Schopenhauer (1788–1860) criticized German idealism and held that a blind, irrational will is the underlying principle of reality. Immanuel Kant (1724–1804) rejected the possibility of objective knowledge of the things in themselves, arguing instead that all experience is shaped by the innate structures of human cognition. Plato (c. 427 – c. 347 BCE) argued for the existence of a realm of eternal forms or ideas in addition to the material world of mutable entities.

On this view, unobservable entities may be invoked in theory construction to aid prediction but should not be taken to exist. Scientific realism is the view that the best scientific theories provide an accurate description of a mind-independent world. Error theory asserts that all value statements are false because there are no values.i Another form of anti-realism maintains that value statements are neither true nor false but meaningless. According to subjectivism, values depend on the attitudes and preferences of https://www.zumospin.net/ individuals. Non-naturalism, another form of realism, maintains that values differ significantly from empirical properties and belong to another domain of reality.
For example, one view suggests that macroscopic objects, such as a chair, depend on the microscopic objects that underlie them, such as elementary particles. The structure of reality concerns the fundamental patterns of being, describing how entities are organized and interact with each other. According to a common view, concrete objects exist in space and time, such as a flower, a horse, and a ship. Events are proposed constituents of reality that occur in time, such as the discovery of penicillin and the Second World War.