Metaphysics

For other uses, seeMetaphysics (disambiguation).

Metaphysicsis the branch ofphilosophythat examines the basic structure ofreality.It is traditionally seen as the study of mind-independent features of the world, but some modern theorists view it as an inquiry into the fundamental categories of human understanding. It is sometimes characterized asfirst philosophyto suggest that it is more fundamental than other forms of philosophical inquiry.

The beginning ofAristotle'sMetaphysics,one of the foundational texts of the discipline

Metaphysics encompasses a wide range of general and abstract topics. It investigates the nature ofexistence,the features all entities have in common, and their division intocategories of being.An influential division is betweenparticularsanduniversals.Particulars are individual unique entities, like a specific apple. Universals are general repeatable entities that characterize particulars, like the colorred.Modal metaphysicsexamines what it means for something to be possible or necessary. Metaphysicians also explore theconcepts of space, time, and change,and their connection tocausalityand thelaws of nature.Other topics include howmind and matter are related,whether everything in the world ispredetermined,and whether there isfree will.

Metaphysicians usevarious methodsto conduct their inquiry. Traditionally, they rely on rationalintuitionsandabstractreasoningbut have more recently also includedempiricalapproaches associated with scientific theories. Due to the abstract nature of its topic, metaphysics has received criticisms questioning the reliability of its methods and the meaningfulness of its theories. Metaphysics is relevant to many fields of inquiry that often implicitly rely on metaphysical concepts and assumptions.

Theroots of metaphysicslie inantiquitywith speculations about the nature and origin of universe, like those found in theUpanishadsinancient India,Daoisminancient China,andpre-Socratic philosophyinancient Greece.During the subsequentmedieval periodin the West, discussions about thenature of universalswere influenced by the philosophies ofPlatoandAristotle.Themodern periodsaw the emergence of various comprehensive systems of metaphysics, many of which embracedidealism.In the 20th century, a "revolt against idealism" was started, metaphysics was once declared meaningless, and then revived with various criticisms of earlier theories and new approaches to metaphysical inquiry.

Definition

Metaphysics is the study of the most general features ofreality,includingexistence,objectsand theirproperties,possibility and necessity,spaceandtime,change,causation,and the relation betweenmatterandmind.It is one of the oldest branches ofphilosophy.

The precise nature of metaphysics is disputed and its characterization has changed in the course of history. Some approaches see metaphysics as a unified field and give a wide-sweeping definition by understanding it as the study of "fundamental questions about the nature of reality" or as an inquiry into theessencesof things. Another approach doubts that the different areas of metaphysics share a set of underlying features and provides instead a fine-grained characterization by listing all the main topics investigated by metaphysicians.Some definitions are descriptive by providing an account of what metaphysicians do while others are normative and prescribe what metaphysicians ought to do.

Two historically influential definitions inancientandmedieval philosophyunderstand metaphysics as the science of thefirst causesand as the study of beingquabeing, that is, the topic of what all beings have in common and to what fundamental categories they belong. In the modern period, the scope of metaphysics expanded to include topics such as the distinction between mind and body andfree will.Some philosophers followAristotlein describing metaphysics as "first philosophy", suggesting that it is the most basic inquiry upon which all other branches of philosophy depend in some way.

Immanuel Kantconceived critical metaphysics as the study of the principles underlying all human thought and experience.

Metaphysics is traditionally understood as a study of mind-independent features of reality. Starting withImmanuel Kant'scritical philosophy,an alternative conception gained prominence that focuses on conceptual schemes rather than external reality. Kant distinguishes transcendent metaphysics, which aims to describe the objective features of reality beyond sense experience, from critical metaphysics, which outlines the aspects and principles underlying all human thought and experience.PhilosopherP. F. Strawsonfurther explored the role of conceptual schemes, contrasting descriptive metaphysics, which articulates conceptual schemes commonly used to understand the world, with revisionary metaphysics, which aims to produce better conceptual schemes.

Metaphysics differs from the individual sciences by studying the most general and abstract aspects of reality. The individual sciences, by contrast, examine more specific and concrete features and restrict themselves to certain classes of entities, such as the focus on physical things inphysics,living entities inbiology,and cultures inanthropology.It is disputed to what extent this contrast is a strict dichotomy rather than a gradual continuum.

Etymology

The wordmetaphysicshas its origin in the ancient Greek wordsmetá(μετά,meaning'after','above',and'beyond'') andphusiká(φυσικά) as a short form ofta metá ta phusiká,meaning'what comes after the physics'.This is often interpreted to mean that metaphysics discusses topics that, due to their generality and comprehensiveness, lie beyond the realm of physics and its focus on empirical observation.Metaphysics got its name by a historical accidentwhenAristotle's bookon this subject was published. Aristotle did not use the termmetaphysicsbut his editor (likelyAndronicus of Rhodes) may have coined it for its title to indicate that this book should be studied after Aristotle's book published onphysics:literallyafter physics.The term entered the English language through the Latin wordmetaphysica.

Branches

The nature of metaphysics can also be characterized in relation to its main branches. An influential division from earlymodern philosophydistinguishes between general and special or specific metaphysics.General metaphysics, also calledontology,takes the widest perspective and studies the most fundamental aspects of being. It investigates the features that all entities share and how entities can be divided into differentcategories.Categories are the most general kinds, such as substance, property,relation,andfact.Ontologists research which categories there are, how they depend on one another, and how they form a system of categories that provides a comprehensive classification of all entities.

Special metaphysics considers being from more narrow perspectives and is divided into subdisciplines based on the perspective they take.Metaphysical cosmologyexamines changeable things and investigates how they are connected to form aworldas a totality extending through space and time.Rational psychology focuses on metaphysical foundations and problems concerning the mind, such as its relation to matter and the freedom of the will. Natural theology studies the divine and its role as the first cause.The scope of special metaphysics overlaps with other philosophical disciplines, making it unclear whether a topic belongs to it or to areas likephilosophy of mindandtheology.

Applied metaphysics is a relatively young subdiscipline. It belongs toapplied philosophyand studies the applications of metaphysics, both within philosophy and other fields of inquiry. In areas likeethicsandphilosophy of religion,it addresses topics like the ontological foundations of moral claims and religious doctrines.Beyond philosophy, its applications include the use of ontologies inartificial intelligence,economics,andsociologyto classify entities.Inpsychiatryandmedicine,it examines the metaphysical status ofdiseases.

Meta-metaphysicsis themetatheoryof metaphysics and investigates the nature and methods of metaphysics. It examines how metaphysics differs from other philosophical and scientific disciplines and assesses its relevance to them. Even though discussions of these topics have a long history in metaphysics, meta-metaphysics has only recently developed into a systematic field of inquiry.

Topics

Existence and categories of being

Main articles:ExistenceandTheory of categories

Metaphysicians often regard existence or being as one of the most basic and general concepts.To exist means to form part ofreality,distinguishing real entities from imaginary ones.According to the orthodox view, existence is a property of properties: if an entity exists then its properties are instantiated.A different position states that existence is a property of individuals, meaning that it is similar to other properties, such as shape or size.It is controversial whether all entities have this property. According toAlexius Meinong,there arenonexistent objects,including merely possible objects likeSanta ClausandPegasus.A related question is whether existence is the same for all entities or whether there are different modes or degrees of existence.For instance, Plato held thatPlatonic forms,which are perfect and immutable ideas, have a higher degree of existence than matter, which can only imperfectly reflect Platonic forms.

Another key concern in metaphysics is the division of entities into distinct groups based on underlying features they share. Theories of categories provide a system of the most fundamental kinds or the highest genera of being by establishing a comprehensive inventory of everything.One of the earliest theories of categories was proposed by Aristotle, who outlined asystem of 10 categories.He argued thatsubstances(e.g. man and horse), are the most important category since all other categories likequantity(e.g. four),quality(e.g. white), and place (e.g. in Athens) are said of substances and depend on them.Kant understood categories as fundamental principles underlying human understanding and developed asystem of 12 categories,divided into the four classes quantity, quality, relation, and modality.More recent theories of categories were proposed byC. S. Peirce,Edmund Husserl,Samuel Alexander,Roderick Chisholm,andE. J. Lowe.Many philosophers rely on the contrast betweenconcrete and abstract objects.According to a common view, concrete objects, like rocks, trees, and human beings, exist in space and time, undergo changes, and impact each other as cause and effect, whereas abstract objects, likenumbersandsets,exist outside space and time, are immutable, and do not engage in causal relations.

Particulars

Particularsare individual entities and include both concrete objects, like Aristotle, the Eiffel Tower, or a specific apple, and abstract objects, like the number 2 or a specific set in mathematics. Also calledindividuals,they are unique, non-repeatable entities and contrast withuniversals,like the color red, which can at the same time exist in several places and characterize several particulars.A widely held view is that particulars instantiate universals but are not themselves instantiated by something else, meaning that they exist in themselves while universals exist in something else. Substratum theory analyzes each particular as a substratum, also calledbare particular,together with various properties. The substratum confers individuality to the particular while the properties express its qualitative features or what it is like. This approach is rejected bybundle theorists,who state that particulars are only bundles of properties without an underlying substratum. Some bundle theorists include in the bundle an individual essence, calledhaecceity,to ensure that each bundle is unique. Another proposal for concrete particulars is that they are individuated by their space-time location.

Concrete particulars encountered in everyday life, like rocks, tables, and organisms, are complex entitiescomposedof various parts. For example, a table is made up of a tabletop and legs, each of which is itself made up of countless particles. The relation between parts and wholes is studied bymereology.The problem of the many is about which groups of entities form mereological wholes, for instance, whether a dust particle on the tabletop is part of the table. According to mereological universalists, every collection of entities forms a whole, meaning that the parts of the table without the dust particle form one whole while they together with it form a second whole. Mereological moderatists hold that certain conditions must be met for a group of entities to compose a whole, for example, that the entities touch one another.Mereological nihilistsreject the idea of wholes altogether, claiming that there are no tables and chairs but only particles that are arranged table-wise and chair-wise.A related mereological problem is whether there are simple entities that have no parts, asatomistsclaim, or not, as continuum theorists contend.

Universals

Main article:Universal (metaphysics)

Universals are general entities, encompassing bothpropertiesandrelations,that express what particulars are like and how they resemble one another. They are repeatable, meaning that they are not limited to a unique existent but can be instantiated by different particulars at the same time. For example, the particularsNelson MandelaandMahatma Gandhiinstantiate the universalhumanity,similar to how a strawberry and a ruby instantiate the universalred.

A topic discussed since ancient philosophy, theproblem of universalsconsists in the challenge of characterizing the ontological status of universals.Realists argue that universals are real, mind-independent entities that exist in addition to particulars. According toPlatonic realists,universals exist independently of particulars, which implies that the universalredwould continue to exist even if there were no red things. A moremoderate form of realism,inspired by Aristotle, states that universals depend on particulars, meaning that they are only real if they are instantiated.Nominalistsreject the idea that universals exist in either form. For them, the world is composed exclusively of particulars.Conceptualistsoffer an intermediate position, stating that universals exist, but only asconceptsin the mind used to order experience by classifying entities.

Naturaland social kinds are often understood as special types of universals. Entities belonging to the same natural kind share certain fundamental features characteristic of the structure of the natural world. In this regard, natural kinds are not an artificially constructed classification but are discovered,usually by the natural sciences, and include kinds likeelectrons,H₂O,and tigers.Scientific realistsand anti-realists disagree about whether natural kinds exist.Social kinds, likemoneyandbaseball,are studied bysocial metaphysicsand characterized as useful social constructions that, while not purely fictional, do not reflect the fundamental structure of mind-independent reality.

Possibility and necessity

The concepts of possibility and necessity convey what can or must be the case, expressed in statements like "it is possible to find a cure for cancer" and "it is necessary that two plus two equals four". They belong to modal metaphysics, which investigates the metaphysical principles underlying them, in particular, why some modal statements are true while others are false.Some metaphysicians hold that modality is a fundamental aspect of reality, meaning that besides facts about what is the case, there are additional facts about what could or must be the case.A different view argues that modal truths are not about an independent aspect of reality but can be reduced to non-modal characteristics, for example, to facts about what properties or linguistic descriptions are compatible with each other or tofictional statements.

Borrowing a term from German philosopherGottfried Wilhelm Leibniz'stheodicy,many metaphysicians use the concept ofpossible worldsto analyze the meaning and ontological ramifications of modal statements. A possible world is a complete and consistent way of how things could have been.For example, thedinosaurswerewiped outin the actual world but there are possible worlds in which they are still alive.According to possible world semantics, a statement is possibly true if it is true in at least one possible world, whereas it is necessarily true if it is true in all possible worlds.Modal realistsargue that possible worlds exist as concrete entities in the same sense as the actual world, with the main difference being that the actual world is the world we live in while other possible worlds are inhabited bycounterparts.This view is controversial and various alternatives have been suggested, for example, that possible worlds only exist as abstract objects or are similar to stories told in works offiction.

Space, time, and change

Main article:Philosophy of space and time

Spaceandtimeare dimensions that entities occupy. Spacetime realists state that space and time are fundamental aspects of reality and exist independently of the human mind. Spacetime idealists, by contrast, hold that space and time are constructs of the human mind, created to organize and make sense of reality.Spacetime absolutism or substantivalism understands spacetime as a distinct object, with some metaphysicians conceptualizing it as a container that holds all other entities within it.Spacetime relationismsees spacetime not as an object but as a network of relations between objects, such as the spatial relation ofbeing next toand the temporal relation ofcoming before.

In the metaphysics of time, an important contrast is between theA-series and the B-series.According to the A-series theory, theflow of timeis real, meaning that events are categorized into the past, present, and future. The present continually moves forward in time and events that are in the present now will eventually change their status and lie in the past. From the perspective of the B-series theory, time is static, and events are ordered by the temporal relations earlier-than and later-than without any essential difference between past, present, and future.Eternalismholds that past, present, and future are equally real, whereaspresentismasserts that only entities in the present exist.

Material objects persist through time and change in the process, like a tree that grows or loses leaves.The main ways of conceptualizing persistence through time areendurantismandperdurantism.According to endurantism, material objects are three-dimensional entities that are wholly present at each moment. As they change, they gain or lose properties but otherwise remain the same. Perdurantists see material objects as four-dimensional entities that extend through time and are made up of differenttemporal parts.At each moment, only one part of the object is present, not the object as a whole. Change means that an earlier part is qualitatively different from a later part. For example, when a banana ripens, there is an unripe part followed by a ripe part.

Causality

Main article:Causality

Causality is the relation between cause and effect whereby one entity produces or affects another entity.For instance, if a person bumps a glass and spills its contents then the bump is the cause and the spill is the effect.Besides the single-case causation between particulars in this example, there is also general-case causation expressed in statements such as "smoking causes cancer".The termagent causationis used when people and their actions cause something.Causation is usually interpreted deterministically, meaning that a cause always brings about its effect. This view is rejected byprobabilistic theories,which claim that the cause merely increases the probability that the effect occurs. This view can explain that smoking causes cancer even though this does not happen in every single case.

Theregularity theory of causation,inspired byDavid Hume's philosophy, states that causation is nothing but aconstant conjunctionin which the mind apprehends that one phenomenon, like putting one's hand in a fire, is always followed by another phenomenon, like a feeling of pain.According to nomic regularity theories, regularities manifest aslaws of naturestudied by science.Counterfactualtheories focus not on regularities but on how effects depend on their causes. They state that effects owe their existence to the cause and would not occur without them.According to primitivism, causation is a basic concept that cannot be analyzed in terms of non-causal concepts, such as regularities or dependence relations. One form of primitivism identifies causal powers inherent in entities as the underlying mechanism.Eliminativists reject the above theories by holding that there is no causation.

Mind and free will

Main articles:MindandFree will

Different approaches toward resolving the mind–body problem

Mind encompasses phenomena likethinking,perceiving,feeling,anddesiringas well as the underlying faculties responsible for these phenomena.Themind–body problemis the challenge of clarifying the relation between physical and mental phenomena. According toCartesian dualism,minds and bodies are distinct substances. They causally interact with each other in various ways but can, at least in principle, exist on their own.This view is rejected bymonists,who argue that reality is made up of only one kind. According toidealism,everything is mental, including physical objects, which may be understood as ideas or perceptions of conscious minds. Materialists, by contrast, state that all reality is at its core material. Some deny that mind exists but the more common approach is to explain mind in terms of certain aspects of matter, such as brain states, behavioraldispositions,or functional roles.Neutral monistsargue that reality is fundamentally neither material nor mental and suggest that matter and mind are both derivative phenomena.A key aspect of the mind–body problem is thehard problem of consciousnessor how to explain that physical systems like brains can produce phenomenal consciousness.

The status of free will as the ability of a person to choose theiractionsis a central aspect of the mind–body problem.Metaphysicians are interested in the relation between free will andcausal determinism—the view that everything in the universe, including human behavior, is determined by preceding events and laws of nature. It is controversial whether causal determinism is true, and, if so, whether this would imply that there is no free will. According toincompatibilism,free will cannot exist in a deterministic world since there is no true choice or control if everything is determined.Hard deterministsinfer from this that there is no free will, whereaslibertariansconclude that determinism must be false.Compatibilistsoffer a third perspective, arguing that determinism and free will do not exclude each other, for instance, because a person can still act in tune with their motivation and choices even if they are determined by other forces. Free will plays a key role in ethics regarding themoral responsibilitypeople have for what they do.

Others

Identityis a relation that every entity has to itself as a form of sameness. It refers to numerical identity when the very same entity is involved, as in the statement "themorning staris theevening star"(both are the planetVenus). In a slightly different sense, it encompasses qualitative identity, also calledexact similarityandindiscernibility,which occurs when two distinct entities are exactly alike, such as perfect identical twins.The principle of the indiscernibility of identicals is widely accepted and holds that numerically identical entities exactly resemble one another. The converse principle, known asidentity of indiscerniblesor Leibniz's Law, is more controversial and states that two entities are numerically identical if they exactly resemble one another.Another distinction is between synchronic and diachronic identity. Synchronic identity relates an entity to itself at the same time, whereas diachronic identity is about the same entity at different times, as in statements like "the table I bought last year is the same as the table in my dining room now".Personal identityis a related topic in metaphysics that uses the termidentityin a slightly different sense and concerns questions like whatpersonhoodis or what makes someone a person.

Various contemporary metaphysicians rely on the concepts oftruth,truth-bearer,andtruthmakerto conduct their inquiry.Truth is a property of being in accord with reality. Truth-bearers are entities that can be true or false, such as linguistic statements and mental representations. A truthmaker of a statement is the entity whose existence makes the statement true.For example, the statement "a tomato is red" is true because there exists a red tomato as its truthmaker.Based on this observation, it is possible to pursue metaphysical research by asking what the truthmakers of statements are, with different areas of metaphysics being dedicated to different types of statements. According to this view, modal metaphysics asks what makes statements about what is possible and necessary true while the metaphysics of time is interested in the truthmakers of temporal statements about the past, present, and future.

Methodology

Metaphysicians employ a variety ofmethodsto develop metaphysical theories and formulate arguments for and against them.Traditionally,a priorimethods have been the dominant approach. They rely on rationalintuitionand abstract reasoning from general principles rather than sensoryexperience.A posterioriapproaches, by contrast, ground metaphysical theories inempirical observationsand scientific theories.Some metaphysicians incorporate perspectives from fields such asphysics,psychology,linguistics,andhistoryinto their inquiry.The two approaches are not mutually exclusive: it is possible to combine elements from both.The method a metaphysician chooses often depends on their understanding of the nature of metaphysics, for example, whether they see it as an inquiry into the mind-independent structure of reality, asmetaphysical realistsclaim, or the principles underlying thought and experience, as somemetaphysical anti-realistscontend.

A prioriapproaches often rely on intuitions—non-inferential impressions about the correctness of specific claims or general principles.For example, arguments for theA-theory of time,which states that time flows from the past through the present and into the future, often rely on pre-theoretical intuitions associated with the sense of the passage of time.Some approaches use intuitions to establish a small set ofself-evidentfundamental principles, known asaxioms,and employdeductive reasoningto build complex metaphysical systems by drawing conclusions from these axioms.Intuition-based approaches can be combined withthought experiments,which help evoke and clarify intuitions by linking them to imagined situations. They usecounterfactual thinkingto assess the possible consequences of these situations.For example, to explore the relation between matter and consciousness, some theorists compare humans tophilosophical zombies—hypothetical creatures identical to humans but withoutconscious experience.A related method relies on commonly accepted beliefs instead of intuitions to formulate arguments and theories. Thecommon-senseapproach is often used to criticize metaphysical theories that deviate significantly from how the average person thinks about an issue. For example, common-sense philosophers have argued thatmereological nihilismis false since it implies that commonly accepted things, like tables, do not exist.

Conceptual analysis,a method particularly prominent inanalytic philosophy,aims to decompose metaphysical concepts into component parts to clarify their meaning and identify essential relations.Inphenomenology,the method ofeidetic variationis used to investigate essential structures underlyingphenomena.This method involves imagining an object and varying its features to determine which ones are essential and cannot be changed.Thetranscendentalmethod is a further approach and examines the metaphysical structure of reality by observing what entities there are and studying theconditions of possibilitywithout which these entities could not exist.

Some approaches give less importance toa priorireasoning and view metaphysics as a practice continuous with the empirical sciences that generalizes their insights while making their underlying assumptions explicit. This approach is known asnaturalized metaphysicsand is closely associated with the work ofWillard Van Orman Quine.He relies on the idea that true sentences from the sciences and other fields haveontological commitments,that is, they imply that certain entities exist.For example, if the sentence "some electrons are bonded to protons" is true then it can be used to justify that electrons and protons exist.Quine used this insight to argue that one can learn about metaphysics by closely analyzingscientific claims to understand what kind of metaphysical picture of the world they presuppose.

In addition to methods of conducting metaphysical inquiry, there are various methodological principles used to decide between competing theories by comparing their theoretical virtues.Ockham's Razoris a well-known principle that gives preference to simple theories, in particular, those that assume that few entities exist. Other principles considerexplanatory power,theoretical usefulness, and proximity to established beliefs.

Criticism

David Humecriticized metaphysicians for trying to gain knowledge outside the field of sensory experience.

Despite its status as one of the main branches of philosophy, metaphysics has received numerous criticisms questioning its legitimacy as a field of inquiry.One criticism argues that metaphysical inquiry is impossible because humans lack the cognitive capacities needed to access the ultimate nature of reality.This line of thought leads toskepticismabout the possibility of metaphysical knowledge. Empiricists often follow this idea, like Hume, who argued that there is no goodsource of metaphysical knowledgesince metaphysics lies outside the field ofempirical knowledgeand relies on dubious intuitions about the realm beyond sensory experience. A related argument favoring the unreliability of metaphysical theorizing points to the deep and lastingdisagreementsabout metaphysical issues, suggesting a lack of overall progress.

Another criticism holds that the problem lies not with human cognitive abilities but with metaphysical statements themselves, which some claim are neither true nor false butmeaningless.According tological positivists,for instance, the meaning of a statement is given by the procedure used toverifyit, usually through theobservationsthat would confirm it. Based on this controversial assumption, they argue that metaphysical statements are meaningless since they make no testable predictions about experience.

A slightly weaker position allows metaphysical statements to have meaning while holding that metaphysical disagreements are merely verbal disputes about different ways to describe the world. According to this view, the disagreement in the metaphysics of composition about whether there are tables or only particles arranged table-wise is a trivial debate about linguistic preferences without any substantive consequences for the nature of reality.The position that metaphysical disputes have no meaning or no significant point is calledmetaphysicalorontological deflationism.This view is opposed by so-calledserious metaphysicians,who contend that metaphysical disputes are about substantial features of the underlying structure of reality.A closely related debate between ontologicalrealistsand anti-realists concerns the question of whether there are any objective facts that determine which metaphysical theories are true.A different criticism, formulated bypragmatists,sees the fault of metaphysics not in its cognitive ambitions or the meaninglessness of its statements, but in its practical irrelevance and lack of usefulness.

Martin Heideggercriticized traditional metaphysics, saying that it fails to distinguish between individual entities and being as their ontological ground. His attempt to reveal the underlying assumptions and limitations in the history of metaphysics to "overcome metaphysics" influencedJacques Derrida's method ofdeconstruction.Derrida employed this approach to criticize metaphysical texts for relying on opposing terms, like presence and absence, which he thought were inherently unstable and contradictory.

There is no consensus about the validity of these criticisms and whether they affect metaphysics as a whole or only certain issues or approaches in it. For example, it could be the case that certain metaphysical disputes are merely verbal while others are substantive.

Relation to other disciplines

Metaphysics is related to many fields of inquiry by investigating their basic concepts and relation to the fundamental structure of reality. For example, the natural sciences rely on concepts such aslaw of nature,causation, necessity, and spacetime to formulate their theories and predict or explain the outcomes of experiments.While scientists primarily focus on applying these concepts to specific situations, metaphysics examines their general nature and how they depend on each other. For instance, physicists formulate laws of nature, likelaws of gravitationandthermodynamics,to describe how physical systems behave under various conditions. Metaphysicians, by contrast, examine what all laws of nature have in common, asking whether they merely describe contingent regularities or express necessary relations.New scientific discoveries have also influenced existing and inspired new metaphysical theories. Einstein'stheory of relativity,for instance, prompted various metaphysicians to conceive space and time as a unified dimension rather than as independent dimensions.Empirically focused metaphysicians often rely on scientific theories to ground their theories about the nature of reality in empirical observations.

Similar issues arise in thesocial scienceswhere metaphysicians investigate their basic concepts and analyze their metaphysical implications. This includes questions like whether social facts emerge from non-social facts, whether social groups and institutions have mind-independent existence, and how they persist through time.Metaphysical assumptions and topics inpsychologyandpsychiatryinclude the questions about the relation between body and mind, whether the nature of the human mind is historically fixed, and what the metaphysical status of diseases is.

Metaphysics is similar to bothphysical cosmologyandtheologyin its exploration of the first causes and the universe as a whole. Key differences are that metaphysics relies on rational inquiry while physical cosmology gives more weight to empirical observations and theology incorporates divinerevelationand other faith-based doctrines.Historically, cosmology and theology were considered subfields of metaphysics.

Suggested Upper Merged Ontology

Entity Physical Object Process Abstract Quantity Proposition Attribute Relation Set or Class

Fundamental categories in theSuggested Upper Merged Ontology

Metaphysics in the form of ontology plays a central role incomputer scienceto classify objects and formally represent information about them. Unlike metaphysicians, computer scientists are usually not interested in providing a single all-encompassing characterization of reality as a whole. Instead, they employ many different ontologies, each one concerned only with a limited domain of entities.For instance, an organization may use an ontology with categories such asperson,company,address,andnameto represent information about clients and employees.Ontologies provide standards or conceptualizations for encoding and storing information in a structured way, enabling computational processes to use and transform their information for a variety of purposes.Someknowledge basesintegrate information from various domains, which brings with it the challenge of handling data that was formulated using diverse ontologies. They address this by providing anupper ontologythat defines concepts at a higher level of abstraction, applicable to all domains. Influential upper ontologies includeSuggested Upper Merged OntologyandBasic Formal Ontology.

Logicas the study ofcorrect reasoningis often used by metaphysicians as a tool to engage in their inquiry and express insights through preciselogical formulas.Another relation between the two fields concerns the metaphysical assumptions associated withlogical systems.Many logical systems likefirst-order logicrely onexistential quantifiersto express existential statements. For instance, in the logical formula$\exists x{\text{Horse}}(x)$the existential quantifier$\exists$is applied to thepredicate${\text{Horse}}$to express that there are horses. Following Quine, various metaphysicians assume that existential quantifiers carryontological commitments,meaning that existential statements imply that the entities over which one quantifies are part of reality.

History

Main article:History of metaphysics

Thetaijitusymbol showsyin and yang,which are two correlated forces discussed in Chinese metaphysics to explore the nature and patterns of existence.

The history of metaphysics examines how the inquiry into the basic structure of reality has evolved in the course of history. Metaphysics originated in the ancient period from speculations about the nature and origin of the cosmos.Inancient India,starting in the 7th century BCE, theUpanishadswere written as religious and philosophical texts that examine howultimate realityconstitutes the ground of all being. They further explore the nature of theselfand how it can reachliberationby understanding ultimate reality.This period also saw the emergence ofBuddhismin the 6th century BCE,which denies the existence of an independent self and understands the world as acyclic process.At about the same timeinancient China,the school ofDaoismwas formed and explored the natural order of the universe, known asDao,and how it is characterized by the interplay ofyin and yangas two correlated forces.

Inancient Greece,metaphysics emerged in the 6th century BCE with thepre-Socraticphilosophers, who gave rational explanations of the cosmos as a whole by examining thefirst principlesfrom which everything arises.Building on their work,Plato(427–347 BCE) formulated histheory of forms,which states that eternal forms or ideas possess the highest kind of reality while the material world is only an imperfect reflection of them.Aristotle(384–322 BCE) accepted Plato's idea that there are universal forms but held that they cannot exist on their own but depend on matter. He also proposed a system of categories and developed a comprehensive framework of the natural world through his theory of thefour causes.Starting in the 4th century BCE,Hellenistic philosophyexplored therational orderunderlying the cosmos and the idea that it is made up ofindivisible atoms.Neoplatonismemerged towards the end of the ancient period in the 3rd century CE and introduced the idea of "the One" as the transcendent and ineffable source of all creation.

Meanwhile, inIndian Buddhism,theMadhyamaka schooldeveloped the idea that all phenomena areinherently emptywithout a permanent essence. The consciousness-only doctrine of theYogācāra schoolstated that experienced objects are mere transformations of consciousness and do not reflect external reality.TheHindu schoolofSamkhyaphilosophyintroduced a metaphysical dualism withpure consciousnessandmatteras its fundamental categories.In China, the school ofXuanxueexplored metaphysical problems such as the contrast between being and non-being.

Boethius's theory of universals influenced many subsequent metaphysicians.

Medieval Western philosophy was profoundly shaped by ancient Greek philosophy.Boethius(477–524 CE) sought to reconcile Plato's and Aristotle's theories of universals, proposing that universals can exist both in matter and mind. His theory inspired the development of nominalism and conceptualism, as in the thought ofPeter Abelard(1079–1142 CE).Thomas Aquinas(1224–1274 CE) understood metaphysics as the discipline investigating different meanings ofbeing,such as the contrast between substance andaccident,and principles applying to all beings, such as theprinciple of identity.William of Ockham(1285–1347 CE) proposedOckham's razor,a methodological principles to choose between competing metaphysical theories.Arabic–Persian philosophy flourished fromthe early 9th century CE to the late 12th century CE,integrating ancient Greek philosophies to interpret and clarify the teachings of theQuran.Avicenna(980–1037 CE) developed a comprehensive philosophical system that examined the contrast between existence and essence and distinguished between contingent and necessary existence.Medieval Indiasaw the emergence of themonistschool ofAdvaita Vedantain the 8th century CE, which holds that everything is one and that the idea of many entities existing independently is anillusion.In China,Neo-Confucianismarose in the 9th century CE and explored theconcept of lias the rational principle that is the ground of being and reflects the order of the universe.

In the early modern period,René Descartes(1596–1650) developed a substance dualism according to which body and mind exist as independent entities that causally interact.This idea was rejected byBaruch Spinoza(1632–1677), who formulated a monist philosophy suggesting that there is only one substance with both physical and mental attributes that develop side-by-side without interacting.Gottfried Wilhelm Leibniz(1646–1716) introduced the concept of possible worlds and articulated a metaphysical system known asmonadology,which views the universe as a collection ofsimple substancessynchronized without causal interaction.Christian Wolff(1679–1754), conceptualized the scope of metaphysics by distinguishing between general and special metaphysics.According to theidealismofGeorge Berkeley(1685–1753), everything is mental, including material objects, which areideas perceived by the mind.David Hume(1711–1776) made various contributions to metaphysics, including theregularity theory of causationand the idea that there are no necessary connections between distinct entities. Hisempiricistoutlook led him to criticize metaphysical theories that seek ultimate principles inaccessible to sensory experience.This skeptical outlook was embraced byImmanuel Kant(1724–1804), who tried to reconceptualize metaphysics as an inquiry into the basic principles and categories of thought and understanding rather than seeing it as an attempt to comprehend mind-independent reality.

Many developments in the later modern period were shaped by Kant's philosophy.German idealistsadopted his idealistic outlook in their attempt to find a unifying principle as the foundation of all reality.Georg Wilhelm Friedrich Hegel(1770–1831) developed a comprehensive system of philosophy that examines how absolute spirit manifests itself.He inspired theBritish idealismofFrancis Herbert Bradley(1846–1924), who interpreted absolute spirit as the all-inclusive totality of being.Arthur Schopenhauer(1788–1860) was a strong critic of German idealism and articulated a differentmetaphysical vision,positing ablind and irrational will as the underlying principle of reality.Pragmatists likeC. S. Peirce(1839–1914) andJohn Dewey(1859–1952) conceived metaphysics as an observational science of the most general features of reality and experience.

Alfred North Whiteheadarticulated the foundations ofprocess philosophyin his workProcess and Reality.

At the turn of the 20th century inanalytic philosophy,philosophers such asBertrand Russell(1872–1970) andG. E. Moore(1873–1958) led a "revolt against idealism".Logical atomists,like Russell and the earlyLudwig Wittgenstein(1889–1951), conceived the world as a multitude of atomic facts, which later inspired metaphysicians such asD. M. Armstrong(1926–2014).Alfred North Whitehead(1861–1947) developedprocess metaphysicsas an attempt to provide a holistic description of both the objective and the subjective realms.

Rudolf Carnap(1891–1970) and otherlogical positivistsformulated a wide-ranging criticism of metaphysical statements, arguing that they are meaningless because there is no way toverify them.Other criticisms of traditional metaphysics identified misunderstandings ofordinary languageas the source of many traditional metaphysical problems or challenged complex metaphysical deductions by appealing to common sense.

The decline of logical positivism led to a revival of metaphysical theorizing.Willard Van Orman Quine(1908–2000) tried to naturalize metaphysics by connecting it to the empirical sciences. His studentDavid Lewis(1941–2001) employed the concept of possible worlds to formulate hismodal realism.Saul Kripke(1940–2022) helped revive discussions of identity andessentialism,distinguishingnecessityas a metaphysical notion from theepistemicnotion ofa priori.

Incontinental philosophy,Edmund Husserl(1859–1938) engaged in ontology through a phenomenological description of experience, while his studentMartin Heidegger(1889–1976) developedfundamental ontologyto clarify the meaning of being.Heidegger's philosophy inspired general criticisms of metaphysics bypostmodernthinkers likeJacques Derrida(1930–2004).Gilles Deleuze's (1925–1995) approach to metaphysics challenged traditionally influential concepts like substance, essence, and identity by reconceptualizing the field through alternative notions such as multiplicity, event, and difference.

See also

• Computational metaphysics
• Doctor of Metaphysics
• Enrico Berti's classification of metaphysics
• Feminist metaphysics
• Fundamental question of metaphysics
• List of metaphysicians
• Metaphysical grounding

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External links

• MetaphysicsatPhilPapers
• Metaphysicsat theIndiana Philosophy Ontology Project
• "Metaphysics".Internet Encyclopedia of Philosophy.
• MetaphysicsatEncyclopædia Britannica
• Metaphysicspublic domain audiobook atLibriVox