This article is about the philosophical study of being. For the information science concept, seeOntology (information science).
Ontology is the philosophical study ofbeing. It is traditionally understood as the subdiscipline ofmetaphysics focused on the most general features ofreality. As one of the most fundamental concepts, being encompasses all of reality and everyentity within it. To articulate the basic structure of being, ontology examines the commonalities among all things and investigates their classification into basic types, such as thecategories ofparticulars anduniversals. Particulars are unique, non-repeatable entities, such as the personSocrates, whereas universals are general, repeatable entities, like the colorgreen. Another distinction exists betweenconcrete objects existing inspace and time, such as a tree, and abstract objects existing outside space and time, like the number 7. Systems of categories aim to provide a comprehensive inventory of reality by employing categories such assubstance,property,relation,state of affairs, andevent.
Ontologists disagree regarding which entities exist at the most basic level.Platonic realism asserts that universals have objective existence, whileconceptualism maintains that universals exist only in the mind, andnominalism denies their existence altogether. Similar disputes pertain tomathematical objects,unobservable objects assumed by scientific theories, andmoral facts.Materialism posits that fundamentally onlymatter exists, whereasdualism asserts thatmind and matter are independent principles. According to some ontologists, objective answers to ontological questions do not exist, with perspectives shaped by differing linguistic practices.
Theorigins of ontology lie in theancient period with speculations about the nature of being and the source of the universe, including ancientIndian,Chinese, andGreek philosophy. In the modern period, philosophers conceived ontology as a distinct academic discipline and coined its name.
Ontology is the study of being. It is the branch ofphilosophy that investigates the nature ofexistence, the features all entities have in common, and how they are divided into basiccategories of being.[1] It aims to discover the foundational building blocks of the world and characterizereality as a whole in its most general aspects.[a] In this regard, ontology contrasts with individual sciences likebiology andastronomy, which restrict themselves to a limited domain of entities, such as living entities and celestial phenomena.[3] In some contexts, the termontology refers not to the general study of being but to a specific ontological theory within this discipline. It can also mean an inventory or aconceptual scheme of a particular domain, such asthe ontology of genes.[4] In this context, an inventory is a comprehensive list of elements.[5] A conceptual scheme is a framework of the key concepts and their relationships.[6]
Ontology is closely related tometaphysics but the exact relation of these two disciplines is disputed. A traditionally influential characterization asserts that ontology is a subdiscipline of metaphysics. According to this view, metaphysics is the study of various aspects of fundamental reality, whereas ontology restricts itself to the most general features of reality.[7] This view sees ontology as general metaphysics, which is to be distinguished from special metaphysics focused on more specific subject matters, likeGod,mind, andvalue.[8] A different conception understands ontology as a preliminary discipline that provides a complete inventory of reality while metaphysics examines the features and structure of the entities in this inventory.[9] Another conception says that metaphysics is about real being while ontology examines possible being or the concept of being.[10] It is not universally accepted that there is a clear boundary between metaphysics and ontology. Some philosophers use both terms as synonyms.[11]
The etymology of the wordontology traces back to theancient Greek termsὄντως (ontos, meaning'being') andλογία (logia, meaning'study of'), literally,'the study of being'. The ancient Greeks did not use the termontology, which was coined by philosophers in the 17th century.[12]
The scope of ontology covers diverse entities, including everyday objects, living beings, celestial bodies, ideas, numbers, and fictional creatures.
Being, orexistence, is the main topic of ontology. It is one of the most general and fundamental concepts, encompassing all ofreality and everyentity within it.[b] In its broadest sense, being only contrasts with non-being or nothingness.[14] It is controversial whether a more substantial analysis of the concept or meaning of being is possible.[15] One proposal understands being as a property possessed by every entity.[16] Critics argue that a thing without being cannot have properties. This means that properties presuppose being and cannot explain it.[17] Another suggestion is that all beings share a set of essential features. According to theEleatic principle, "power is the mark of being", meaning that only entities withcausal influence truly exist.[18] A controversial proposal by philosopherGeorge Berkeley suggests that all existence is mental. He expressed thisimmaterialism in his slogan "to be is to be perceived".[19]
Depending on the context, the termbeing is sometimes used with a more limited meaning to refer only to certain aspects of reality. In one sense, being is unchanging and permanent, in contrast to becoming, which implies change.[20] Another contrast is between being, as what truly exists, andphenomena, as what appears to exist.[21] In some contexts, being expresses the fact that something is whileessence expresses itsqualities or what it is like.[22]
Ontologists often divide being into fundamental classes or highest kinds, calledcategories of being.[23] Proposed categories include substance,property,relation,state of affairs, andevent.[24] They can be used to provide systems of categories, which offer a comprehensive inventory of reality in which every entity belongs to exactly one category.[23] Some philosophers, likeAristotle, say that entities belonging to different categories exist in distinct ways. Others, likeJohn Duns Scotus, insist that there are no differences in the mode of being, meaning thateverything exists in the same way.[25] A related dispute is whether some entities have a higher degree of being than others, an idea already found inPlato's work. The more common view in contemporary philosophy is that a thing either exists or not with no intermediary states or degrees.[26]
TheTaj Mahal is a particular entity while the colorgreen is a universal entity.
A central distinction in ontology is between particular and universal entities. Particulars, also calledindividuals, are unique, non-repeatable entities, likeSocrates, theTaj Mahal, andMars.[29] Universals are general, repeatable entities, like the colorgreen, the formcircularity, and the virtuecourage. Universals express aspects or features shared by particulars. For example,Mount Everest andMount Fuji are particulars characterized by the universalmountain.[30]
Universals can take the form of properties or relations.[31][c] Properties describe the characteristics of things. They are features or qualities possessed by an entity.[33] Properties are often divided intoessential and accidental properties. A property is essential if an entity must have it; it is accidental if the entity can exist without it.[34] For instance,having three sides is an essential property of a triangle, whereasbeing red is an accidental property.[35][d] Relations are ways how two or more entities stand to one another. Unlike properties, they apply to several entities and characterize them as a group.[37] For example,being a city is a property whilebeing east of is a relation, as in "Kathmandu is a city" and "Kathmandu is east ofNew Delhi".[38] Relations are often divided intointernal and external relations. Internal relations depend only on the properties of the objects they connect, like the relation ofresemblance. External relations express characteristics that go beyond what the connected objects are like, such as spatial relations.[39]
Substances[e] play an important role in the history of ontology as the particular entities that underlie and support properties and relations. They are often considered the fundamental building blocks of reality that can exist on their own, while entities like properties and relations cannot exist without substances. Substances persist through changes as they acquire or lose properties. For example, when a tomato ripens, it loses the propertygreen and acquires the propertyred.[41]
States of affairs are complex particular entities that have several other entities as their components. The state of affairs "Socrates is wise" has two components: the individualSocrates and the propertywise. States of affairs that correspond to reality are calledfacts.[42][f] Facts aretruthmakers of statements, meaning that whether a statement is true or false depends on the underlying facts.[44]
Events are particular entities[g] that occur in time, like thefall of the Berlin Wall and thefirst moon landing. They usually involve some kind of change, like the lawn becoming dry. In some cases, no change occurs, like the lawn staying wet.[46] Complex events, also calledprocesses, are composed of a sequence of events.[47]
Concrete objects are entities that exist in space and time, such as a tree, a car, and a planet. They have causal powers and can affect each other, like when a car hits a tree and both are deformed in the process. Abstract objects, by contrast, are outside space and time, such as the number 7 and the set ofintegers. They lack causal powers and do not undergo changes.[48][h] The existence and nature of abstract objects remain subjects of philosophical debate.[50]
Concrete objects encountered in everyday life are complex entities composed of various parts. For example, a book is made up of two covers and the pages between them. Each of these components is itself constituted of smaller parts, likemolecules,atoms, andelementary particles.[51]Mereology studies the relation between parts and wholes. One position in mereology says that every collection of entities forms a whole. According to another view, this is only the case for collections that fulfill certain requirements, for instance, that the entities in the collection touch one another.[52] The problem of material constitution asks whether or in what sense a whole should be considered a new object in addition to the collection of parts composing it.[53]
Ontological dependence is a relation between entities. An entity depends ontologically on another entity if the first entity cannot exist without the second entity.[57] For instance, the surface of an apple cannot exist without the apple.[58] An entity is ontologically independent if it does not depend on anything else, meaning that it is fundamental and can exist on its own. Ontological dependence plays a central role in ontology and its attempt to describe reality on its most fundamental level.[59] It is closely related tometaphysical grounding, which is the relation between a ground and the facts it explains.[60]
Anontological commitment of a person or a theory is an entity that exists according to them.[61] For instance, a person whobelieves in God has an ontological commitment toGod.[62] Ontological commitments can be used to analyze which ontologies people explicitly defend or implicitly assume. They play a central role in contemporary metaphysics when trying to decide between competing theories. For example, theQuine–Putnam indispensability argument defendsmathematical Platonism, asserting that numbers exist because the best scientific theories are ontologically committed to numbers.[63]
Possibility and necessity are further topics in ontology. Possibility describes what can be the case, as in "it is possible thatextraterrestrial life exists". Necessity describes what must be the case, as in "it is necessary that three plus two equals five". Possibility and necessity contrast with actuality, which describes what is the case, as in "Doha is the capital ofQatar". Ontologists often use the concept ofpossible worlds to analyze possibility and necessity.[64] A possible world is a complete and consistent way how things could have been.[65] For example,Haruki Murakami was born in 1949 in the actual world but there are possible worlds in which he was born at a different date. Using this idea,possible world semantics says that a sentence is possibly true if it is true in at least one possible world. A sentence is necessarily true if it is true in all possible worlds.[66]
In ontology,identity means that two things are the same. Philosophers distinguish between qualitative and numerical identity. Two entities are qualitatively identical if they have exactly the same features, such as perfect identical twins. This is also calledexact similarity andindiscernibility. Numerical identity, by contrast, means that there is only a single entity. For example, if Fatima is the mother of Leila and Hugo then Leila's mother is numerically identical to Hugo's mother.[67] Another distinction is between synchronic and diachronic identity. Synchronic identity relates an entity to itself at the same time. Diachronic identity relates an entity to itself at different times, as in "the woman who bore Leila three years ago is the same woman who bore Hugo this year".[68]
There are different and sometimes overlapping ways to divide ontology into branches. Pure ontology focuses on the most abstract topics associated with the concept and nature of being. It is not restricted to a specific domain of entities and studies existence and the structure of reality as a whole.[69] Pure ontology contrasts withapplied ontology, also called domain ontology. Applied ontology examines the application of ontological theories and principles to specific disciplines and domains, often in the field of science.[70] It considers ontological problems in regard to specific entities such asmatter,mind,numbers,God, and cultural artifacts.[71]
Social ontology, a major subfield of applied ontology, studies social kinds, likemoney,gender,society, andlanguage. It aims to determine the nature and essential features of these concepts while also examining their mode of existence.[72] According to a common view, social kinds are useful constructions to describe the complexities of social life. This means that they are not pure fictions but, at the same time, lack the objective or mind-independent reality of natural phenomena like elementary particles, lions, and stars.[73] In the fields ofcomputer science,information science, andknowledge representation, applied ontology is interested in the development of formal frameworks to encode and store information about a limited domain of entities in a structured way.[74] A related application ingenetics isGene Ontology, which is a comprehensive framework for the standardized representation of gene-related information across species and databases.[75]
Formal ontology is the study of objects in general while focusing on their abstract structures and features. It divides objects into different categories based on the forms they exemplify. Formal ontologists often rely on the tools offormal logic to express their findings in an abstract and general manner.[76][i] Formal ontology contrasts with material ontology, which distinguishes between different areas of objects and examines the features characteristic of a specific area.[78] Examples are ideal spatial beings in the area of geometry and living beings in the area of biology.[79]
Descriptive ontology aims to articulate the conceptual scheme underlying how people ordinarily think about the world. Prescriptive ontology departs from common conceptions of the structure of reality and seeks to formulate a new and better conceptualization.[80]
Another contrast is between analytic and speculative ontology. Analytic ontology examines the types and categories of being to determine what kinds of things could exist and what features they would have. Speculative ontology aims to determine which entities actually exist, for example, whether there are numbers or whether time is an illusion.[81]
Martin Heidegger proposed fundamental ontology to study the meaning of being.
Metaontology studies the underlying concepts, assumptions, and methods of ontology. Unlike other forms of ontology, it does not ask "what exists" but "what does it mean for something to exist" and "how can people determine what exists".[82] It is closely related tofundamental ontology, an approach developed by philosopherMartin Heidegger that seeks to uncover the meaning of being.[83]
The termrealism is used for various theories[j] that affirm that some kind of phenomenon is real or has mind-independent existence. Ontological realism is the view that there areobjective facts about what exists and what the nature and categories of being are. Ontological realists do not make claims about what those facts are, for example, whether elementary particles exist. They merely state that there are mind-independent facts that determine which ontological theories are true.[85] This idea is denied by ontological anti-realists, also called ontological deflationists, who say that there are no substantive facts one way or the other.[86] According to philosopherRudolf Carnap, for example, ontological statements are relative to language and depend on the ontological framework of the speaker. This means that there are no framework-independent ontological facts since different frameworks provide different views while there is no objectively right or wrong framework.[87]
Plato (left) andAristotle (right) disagreed on whether universals can exist without matter.
In a more narrow sense, realism refers to the existence of certain types of entities.[88] Realists about universals say that universals have mind-independent existence. According toPlatonic realists, universals exist not only independent of the mind but also independent of particular objects that exemplify them. This means that the universalred could exist by itself even if there were no red objects in the world. Aristotelian realism, also calledmoderate realism, rejects this idea and says that universals only exist as long as there are objects that exemplify them.Conceptualism, by contrast, is a form of anti-realism, stating that universals only exist in the mind as concepts that people use to understand and categorize the world.Nominalists defend a strong form of anti-realism by saying that universals have no existence. This means that the world is entirely composed of particular objects.[89]
Mathematical realism, a closely related view in thephilosophy of mathematics, says that mathematical facts exist independently of human language, thought, and practices and are discovered rather than invented. According to mathematical Platonism, this is the case because of the existence ofmathematical objects, like numbers and sets. Mathematical Platonists say that mathematical objects are as real as physical objects, like atoms and stars, even though they are not accessible toempirical observation.[90] Influential forms of mathematical anti-realism include conventionalism, which says that mathematical theories are trivially true simply by how mathematical terms are defined, and gameformalism, which understands mathematics not as a theory of reality but as a game governed by rules of string manipulation.[91]
Modal realism is the theory that in addition to the actual world, there are countlesspossible worlds as real and concrete as the actual world. The primary difference is that the actual world is inhabited by us while other possible worlds are inhabited by ourcounterparts. Modal anti-realists reject this view and argue that possible worlds do not have concrete reality but exist in a different sense, for example, as abstract or fictional objects.[92]
Scientific realists say that the scientific description of the world is an accurate representation of reality.[k] It is of particular relevance in regard to things thatcannot be directly observed by humans but are assumed to exist by scientific theories, like electrons, forces, and laws of nature.Scientific anti-realism says that scientific theories are not descriptions of reality butinstruments to predict observations and the outcomes of experiments.[94]
Moral realists claim that there exist mind-independent moral facts. According to them, there are objective principles that determine which behavior is morally right.Moral anti-realists either claim that moral principles are subjective and differ between persons and cultures, a position known asmoral relativism, or outright deny the existence of moral facts, a view referred to asmoral nihilism.[95]
Monocategorical theories say that there is only one fundamental category, meaning that every single entity belongs to the same universal class.[96] For example, some forms of nominalism state that only concrete particulars exist while some forms ofbundle theory state that only properties exist.[97] Polycategorical theories, by contrast, hold that there is more than one basic category, meaning that entities are divided into two or more fundamental classes. They take the form of systems of categories, which list the highest genera of being to provide a comprehensive inventory of everything.[98]
The closely related discussion betweenmonism anddualism is about the most fundamental types that make up reality. According to monism, there is only one kind of thing or substance on the most basic level.[99]Materialism is an influential monist view; it says that everything is material. This means that mental phenomena, such as beliefs, emotions, and consciousness, either do not exist or exist as aspects of matter, like brain states.Idealists take the converse perspective, arguing that everything is mental. They may understand physical phenomena, like rocks, trees, and planets, as ideas or perceptions of conscious minds.[100]Neutral monism occupies a middle ground by saying that both mind and matter are derivative phenomena.[101] Dualists state that mind and matter exist as independent principles, either asdistinct substances ordifferent types of properties.[102] In a slightly different sense, monism contrasts withpluralism as a view not about the number of basic types but the number of entities. In this sense, monism is the controversial position that only a single all-encompassing entity exists in all of reality.[l] Pluralism is more commonly accepted and says that several distinct entities exist.[104]
The historically influentialsubstance-attribute ontology is a polycategorical theory. It says that reality is at its most fundamental level made up of unanalyzable substances that are characterized by universals, such as the properties an individual substance has or relations that exist between substances.[105] The closely related to substratum theory says that each concrete object is made up of properties and a substratum. The difference is that the substratum is not characterized by properties: it is a featureless orbare particular that merely supports the properties.[106]
Various alternative ontological theories have been proposed that deny the role of substances as the foundational building blocks of reality.[107] Stuff ontologies say that the world is not populated by distinct entities but by continuous stuff that fills space. This stuff may take various forms and is often conceived as infinitely divisible.[108][m] According toprocess ontology, processes or events are the fundamental entities. This view usually emphasizes that nothing in reality is static, meaning that being is dynamic and characterized by constant change.[110] Bundle theories state that there are no regular objects but only bundles of co-present properties. For example, a lemon may be understood as a bundle that includes the properties yellow, sour, and round. According to traditional bundle theory, the bundled properties are universals, meaning that the same property may belong to several different bundles. According totrope bundle theory, properties are particular entities that belong to a single bundle.[111]
Some ontologies focus not on distinct objects but on interrelatedness. According to relationalism, all of reality is relational at its most fundamental level.[112][n]Ontic structural realism agrees with this basic idea and focuses on how these relations form complex structures. Some structural realists state that there is nothing but relations, meaning that individual objects do not exist. Others say that individual objects exist but depend on the structures in which they participate.[114] Fact ontologies present a different approach by focusing on how entities belonging to different categories come together to constitute the world. Facts, also known as states of affairs, are complex entities; for example, the fact thatthe Earth is a planet consists of the particular objectthe Earth and the propertybeing a planet. Fact ontologies state that facts are the fundamental constituents of reality, meaning that objects, properties, and relations cannot exist on their own and only form part of reality to the extent that they participate in facts.[115][o]
In thehistory of philosophy, various ontological theories based on several fundamental categories have been proposed. One of the first theories of categories was suggested byAristotle, whose system includes ten categories: substance,quantity,quality, relation, place, date, posture, state, action, and passion.[117] An early influential system of categories in Indian philosophy, first proposed in theVaisheshika school, distinguishes between six categories:substance, quality, motion, universal, individuator, and inherence.[118]Immanuel Kant'stranscendental idealism includes a system of twelve categories, which Kant saw as pure concepts of understanding. They are subdivided into four classes: quantity, quality, relation, and modality.[119] In more recent philosophy, theories of categories were developed byC. S. Peirce,Edmund Husserl,Samuel Alexander,Roderick Chisholm, andE. J. Lowe.[120]
The dispute between constituent and relational ontologies[p] concerns the internal structure of concrete particular objects. Constituent ontologies say that objects have an internal structure with properties as their component parts. Bundle theories are an example of this position: they state that objects are bundles of properties. This view is rejected by relational ontologies, which say that objects have no internal structure, meaning that properties do not inhere in them but are externally related to them. According to one analogy, objects are like pin-cushions and properties are pins that can be stuck to objects and removed again without becoming a real part of objects. Relational ontologies are common in certain forms of nominalism that reject the existence of universal properties.[122]
Hierarchical ontologies state that the world is organized into levels. Entities on all levels are real but low-level entities are more fundamental than high-level entities. This means that they can exist without high-level entities while high-level entities cannot exist without low-level entities.[123] One hierarchical ontology says that elementary particles are more fundamental than the macroscopic objects they compose, like chairs and tables. Other hierarchical theories assert that substances are more fundamental than their properties and that nature is more fundamental than culture.[124] Flat ontologies, by contrast, deny that any entity has a privileged status, meaning that all entities exist on the same level. For them, the main question is only whether something exists rather than identifying the level at which it exists.[125][q]
The ontological theories ofendurantism andperdurantism aim to explain how material objects persist through time. Endurantism is the view that material objects are three-dimensional entities that travel through time while being fully present in each moment. They remain the same even when they gain or lose properties as they change. Perdurantism is the view that material objects are four-dimensional entities that extend not just through space but also through time. This means that they are composed oftemporal parts and, at any moment, only one part of them is present but not the others. According to perdurantists, change means that an earlier part exhibits different qualities than a later part. When a tree loses its leaves, for instance, there is an earlier temporal part with leaves and a later temporal part without leaves.[127]
Differential ontology is apoststructuralist approach interested in the relation between the concepts of identity anddifference. It says that traditional ontology sees identity as the more basic term by first characterizing things in terms of their essential features and then elaborating differences based on this conception. Differential ontologists, by contrast, privilege difference and say that the identity of a thing is a secondary determination that depends on how this thing differs from other things.[128]
Object-oriented ontology belongs to the school ofspeculative realism and examines the nature and role of objects. It sees objects as the fundamental building blocks of reality. As a flat ontology, it denies that some entities have a more fundamental form of existence than others. It uses this idea to argue that objects exist independently of human thought and perception.[129]
Methods of ontology are ways of conducting ontological inquiry and deciding between competing theories. There is no single standard method; the diverse approaches are studied bymetaontology.[130]
Conceptual analysis is a method to understand ontological concepts and clarify their meaning.[131] It proceeds by analyzing their component parts and thenecessary and sufficient conditions under which a concept applies to an entity.[132] This information can help ontologists decide whether a certain type of entity, such as numbers, exists.[133]Eidetic variation is a related method inphenomenological ontology that aims to identify the essential features of different types of objects. Phenomenologists start by imagining an example of the investigated type. They proceed by varying the imagined features to determine which ones cannot be changed, meaning they are essential.[134][r] Thetranscendental method begins with a simple observation that a certain entity exists. In the following step, it studies the ontological repercussions of this observation by examining how it is possible or whichconditions are required for this entity to exist.[136]
Another approach is based onintuitions in the form of non-inferential impressions about the correctness of general principles.[137] These principles can be used as thefoundation on which an ontological system is built and expanded usingdeductive reasoning.[138] A further intuition-based method relies onthought experiments to evoke new intuitions. This happens by imagining a situation relevant to an ontological issue and then employingcounterfactual thinking to assess the consequences of this situation.[139] For example, some ontologists examine the relation between mind and matter by imaginingcreatures identical to humans but without consciousness.[140]
Naturalistic methods rely on the insights of the natural sciences to determine what exists.[141] According to an influential approach byWillard Van Orman Quine, ontology can be conducted by analyzing[s] the ontological commitments of scientific theories. This method is based on the idea that scientific theories provide the most reliable description of reality and that their power can be harnessed by investigating the ontological assumptions underlying them.[143]
Principles of theory choice offer guidelines for assessing the advantages and disadvantages of ontological theories rather than guiding their construction.[144] The principle ofOckham's Razor says that simple theories are preferable.[145] A theory can be simple in different respects, for example, by using very few basic types or by describing the world with a small number of fundamental entities.[146] Ontologists are also interested in the explanatory power of theories and give preference to theories that can explain many observations.[147] A further factor is how close a theory is tocommon sense. Some ontologists use this principle as an argument against theories that are very different from how ordinary people think about the issue.[148]
In applied ontology,ontological engineering is the process of creating and refining conceptual models of specific domains.[149] Developing a new ontology from scratch involves various preparatory steps, such as delineating the scope of the domain one intends to model and specifying the purpose and use cases of the ontology. Once the foundational concepts within the area have been identified, ontology engineers proceed by defining them and characterizing the relations between them. This is usually done in aformal language to ensure precision and, in some cases, automaticcomputability. In the following review phase, the validity of the ontology is assessed using test data.[150] Various more specific instructions for how to carry out the different steps have been suggested. They include theCyc method, Grüninger and Fox's methodology, and so-called METHONTOLOGY.[151] In some cases, it is feasible to adapt a pre-existing ontology to fit a specific domain and purpose rather than creating a new one from scratch.[152]
Ontology overlaps with many disciplines, includinglogic, the study ofcorrect reasoning.[153] Ontologists often employlogical systems to express their insights, specifically in the field of formal ontology. Of particular interest to them is theexistential quantifier (), which is used to express what exists. Infirst-order logic, for example, the formula states that dogs exist.[154] Some philosophers study ontology by examining the structure of thought and language, saying that they reflect the structure of being.[155] Doubts about the accuracy ofnatural language have led some ontologists to seek a newformal language, termedontologese, for a better representation of the fundamental structure of reality.[156]
Ontologies are often used in information science to provide a conceptual scheme or inventory of a specific domain, making it possible to classify objects and formally represent information about them. This is of specific interest to computer science, which buildsdatabases to store this information and defines computational processes to automatically transform and use it.[158] For instance, to encode and store information about clients and employees in a database, an organization may use an ontology with categories such as person, company, address, and name.[159] In some cases, it is necessary to exchange information belonging to different domains or to integrate databases using distinct ontologies. This can be achieved with the help ofupper ontologies, which are not limited to one specific domain. They use general categories that apply to most or all domains, likeSuggested Upper Merged Ontology andBasic Formal Ontology.[160]
Similar applications of ontology are found in various fields seeking to manage extensive information within a structured framework.Protein Ontology is a formal framework for the standardized representation ofprotein-related entities and their relationships.[161]Gene Ontology andSequence Ontology serve a similar purpose in the field ofgenetics.[162] Environment Ontology is a knowledge representation focused onecosystems and environmental processes.[163]Friend of a Friend provides a conceptual framework to represent relations between people and their interests and activities.[164]
The topic of ontology has received increased attention inanthropology since the 1990s, sometimes termed the "ontological turn".[165] This type of inquiry is focused on how people from different cultures experience and understand the nature of being. Specific interest has been given to the ontological outlook ofIndigenous people and how it differs from a Western perspective.[166] As an example of this contrast, it has been argued that various indigenous communities ascribeintentionality to non-human entities, like plants, forests, or rivers. This outlook is known asanimism[167] and is also found inNative American ontologies, which emphasize the interconnectedness of all living entities and the importance of balance and harmony with nature.[168]
Ontology is closely related totheology and its interest in theexistence of God as an ultimate entity. Theontological argument, first proposed byAnselm of Canterbury, attempts to prove the existence of the divine. It definesGod as the greatest conceivable being. From this definition it concludes that God must exist since God would not be the greatest conceivable being if God lacked existence.[169] Another overlap in the two disciplines is found in ontological theories that use God or an ultimate being as the foundational principle of reality. Heidegger criticized this approach, terming itontotheology.[170]
Kapila was one of the founding fathers of the dualist school ofSamkhya.[171]
The roots of ontology inancient philosophy are speculations about the nature of being and the source of the universe. Discussions of the essence of reality are found in theUpanishads, ancient Indian scriptures dating from as early as 700 BCE. They say that the universe has a divine foundation and discuss in what senseultimate reality is one or many.[172]Samkhya, the firstorthodox school of Indian philosophy,[t] formulated anatheist dualist ontology based on the Upanishads, identifyingpure consciousness andmatter as its two foundational principles.[174] The laterVaisheshika school[u] proposed a comprehensive system of categories.[176] Inancient China,Laozi's (6th century BCE)[v]Taoism examines the underlying order of the universe, known asTao, and how this order is shaped by the interaction of two basic forces,yin and yang.[178] The philosophical movement ofXuanxue emerged in the 3rd century CE and explored the relation between being and non-being.[179]
Starting in the 6th century BCE,Presocratic philosophers inancient Greece aimed to provide rational explanations of the universe. They suggested that a first principle, such as water or fire, is the primal source of all things.[180]Parmenides (c. 515–450 BCE) is sometimes considered the founder of ontology because of his explicit discussion of the concepts of being and non-being.[181] Inspired by Presocratic philosophy,Plato (427–347 BCE) developed histheory of forms. It distinguishes between unchangeable perfect forms and matter, which has a lower degree of existence and imitates the forms.[182]Aristotle (384–322 BCE) suggested an elaborate system of categories that introduced the concept of substance as the primary kind of being.[183] The school ofNeoplatonism arose in the 3rd century CE and proposed an ineffable source of everything, calledthe One, which is more basic than being itself.[184]
Theproblem of universals was an influential topic in medieval ontology.Boethius (477–524 CE) suggested that universals can exist not only in matter but also in the mind. This view inspiredPeter Abelard (1079–1142 CE), who proposed that universals exist only in the mind.[185]Thomas Aquinas (1224–1274 CE) developed and refined fundamental ontological distinctions, such as the contrast between existence andessence, between substance and accidents, and betweenmatter and form.[186] He also discussed thetranscendentals, which are the most general properties or modes of being.[187]John Duns Scotus (1266–1308) argued that all entities, including God,exist in the same way and that each entity has a unique essence, calledhaecceity.[188]William of Ockham (c. 1287–1347 CE) proposed that one can decide between competing ontological theories by assessing which one uses the smallest number of elements, a principle known asOckham's razor.[189]
TheNeo-Confucian philosopherZhu Xi conceived the concept ofli as the organizing principle of the universe.[190]
InArabic-Persian philosophy,Avicenna (980–1037 CE) combined ontology withtheology. He identified God as a necessary being that is the source of everything else, which only has contingent existence.[191] In 8th-centuryIndian philosophy, the school ofAdvaita Vedanta emerged. It says that only a single all-encompassing entity exists, stating that the impression of a plurality of distinct entities is anillusion.[192] Starting in the 13th century CE, theNavya-Nyāya school built on Vaisheshika ontology with a particular focus on the problem of non-existence and negation.[193] 9th-century China saw the emergence ofNeo-Confucianism, which developed the idea that a rational principle, known asli, is the ground of being and order of the cosmos.[194]
René Descartes (1596–1650) formulated a dualist ontology at the beginning of the modern period. It distinguishes between mind and matter as distinct substances that causally interact.[195] Rejecting Descartes's dualism,Baruch Spinoza (1632–1677) proposed a monist ontology according to which there is only a single entity that is identical toGod and nature.[196]Gottfried Wilhelm Leibniz (1646–1716), by contrast, said that the universe is made up of many simple substances, which are synchronized but do not interact with one another.[197]John Locke (1632–1704) proposed his substratum theory, which says that each object has a featureless substratum that supports the object's properties.[198]Christian Wolff (1679–1754) was influential in establishing ontology as a distinct discipline, delimiting its scope from other forms of metaphysical inquiry.[199]George Berkeley (1685–1753) developed an idealist ontology according to which material objects are ideas perceived by minds.[200]
Immanuel Kant (1724–1804) rejected the idea that humans can have direct knowledge of independently existing things and their nature, limiting knowledge to the field of appearances. For Kant, ontology does not study external things but provides a system ofpure concepts of understanding.[201] Influenced by Kant's philosophy,Georg Wilhelm Friedrich Hegel (1770–1831) linked ontology andlogic. He said that being and thought are identical and examined their foundational structures.[202]Arthur Schopenhauer (1788–1860) rejected Hegel's philosophy and proposed that the world is an expression of ablind and irrational will.[203]Francis Herbert Bradley (1846–1924) saw absolute spirit as the ultimate and all-encompassing reality[204] while denying that there are any external relations.[205] In Indian philosophy,Swami Vivekananda (1863–1902) expanded on Advaita Vedanta, emphasizing the unity of all existence.[206]Sri Aurobindo (1872–1950) sought to understand the world as an evolutionary manifestation of a divine consciousness.[207]
At the beginning of the 20th century,Edmund Husserl (1859–1938) developedphenomenology and employed its method, the description ofexperience, to address ontological problems.[208] This idea inspired his studentMartin Heidegger (1889–1976) to clarify the meaning of being by exploring the mode of human existence.[209]Jean-Paul Sartre responded to Heidegger's philosophy by examining the relation between being andnothingness from the perspective of human existence, freedom, and consciousness.[210] Based on the phenomenological method,Nicolai Hartmann (1882–1950) developed a complex hierarchical ontology that divides reality into four levels: inanimate, biological, psychological, and spiritual.[211]
Alexius Meinong (1853–1920) articulated a controversial ontological theory that includes nonexistent objects as part of being.[212] Arguing against this theory,Bertrand Russell (1872–1970) formulated a fact ontology known aslogical atomism. This idea was further refined by the earlyLudwig Wittgenstein (1889–1951) and inspiredD. M. Armstrong's (1926–2014) ontology.[213]Alfred North Whitehead (1861–1947), by contrast, developed a process ontology.[214]Rudolf Carnap (1891–1970) questioned the objectivity of ontological theories by claiming that what exists depends on one's linguistic framework.[215] He had a strong influence onWillard Van Orman Quine (1908–2000), who analyzed the ontological commitments of scientific theories to solve ontological problems.[216] Quine's studentDavid Lewis (1941–2001) formulated the position of modal realism, which says that possible worlds are as real and concrete as the actual world.[217] Since the end of the 20th century, interest in applied ontology has risen in computer and information science with the development of conceptual frameworks for specific domains.[218]
^This focus on general principles rather than specific entities is traditionally expressed in the characterization of ontology as the science ofbeing qua being orbeing insofar as it is being.[2]
^When used as a countable noun,a being is the same asan entity.[13]
^This idea is opposed by trope theorists, who understand properties and relations as particular entities.[32]
^Other influential distinctions are between intrinsic and extrinsic properties, between determinate or determinable properties, and between categorical and dispositional properties.[36]
^The termsubstance has a specific meaning in philosophy distinct from ordinary language expressions such aschemical substance orsubstance abuse.[40]
^David Armstrong and his followers use a different terminology that does not distinguish between states of affairs and facts.[43]
^Some ontologists also use the term in a less common sense to refer to universals in the form of event types.[45]
^The idea of formal ontology was first formulated by phenomenologistEdmund Husserl, who studied objects in general by relying on fundamental categories such as unity, plurality, state of affairs, part, and whole. He examined the relations between these categories and how they depend on one another.[77]
^They are usually distinguished by combining them with a qualifier to express which type is meant, as inontological realism,mathematical realism, andmoral realism. The qualifiers are sometimes left out if the meaning is clear in the context.[84]
^The exact definition of the term is disputed.[93]
^This view contrasts with atomism, which states that the world is composed of discrete, indivisible units.[109]
^For example,relationalism about spacetime says that space and time are nothing but relations. Spacetime substantivalists reject this view and state that spacetime is a distinct object rather than a relational structure between objects.[113]
^This is expressed in a slogan byLudwig Wittgenstein: "The world is the totality of facts, not of things".[116]
^In this context, the term "relational ontology" has a slightly different meaning than the term "relationalism", which says that, at the most basic level, reality is made up of relations.[121]
^Some flat ontologies allow that there are entities on higher levels but stipulate that they are reducible to the lowest level, meaning that they are no addition to being.[126]
^For example, it is essential for a triangle to have three sides since it ceases to be a triangle if a fourth side is added.[135]
^An essential step in Quine's analysis is to translate the theory intofirst-order logic to make its ontological assumptions explicit.[142]
^Its initial ideas were developed in the 7th and 6th centuries BCE but it was not until 350 CE that it received its classical and systematic formulation.[173]
^The founding text of the school was written 500–300 BCE and the first major commentary on it is dated 400 CE.[175]
^The exact date is disputed and some theorists suggest a later date between the 4th and 3rd centuries BCE.[177]
Aertsen, Jan A. (2009)."Aquinas, St. Thomas". In Kim, Jaekwon; Sosa, Ernest; Rosenkrantz, Gary S. (eds.).A Companion to Metaphysics. John Wiley & Sons.ISBN978-1-4051-5298-3.Archived from the original on 2024-06-22. Retrieved2024-06-26.
Berthrong, John H."Neo-Confucian Philosophy".Internet Encyclopedia of Philosophy.Archived from the original on 6 February 2024. Retrieved31 March 2024.
Berto, Francesco; Jago, Mark (2023)."Impossible Worlds".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 10 February 2021. Retrieved3 July 2024.
Lawrence, David Peter (2018). "Tantra and Kashmiri Śaivism". In Bilimoria, Puruṣottama; Rayner, Amy (eds.).History of Indian Philosophy. Routledge.ISBN978-0-415-30976-9.
Boedeker, Edgar C. (2008)."Phenomenology". In Dreyfus, Hubert L.; Wrathall, Mark A. (eds.).A Companion to Heidegger. John Wiley & Sons.ISBN978-0-470-99724-6.Archived from the original on 2024-06-25. Retrieved2024-06-26.
Brown, James Robert; Fehige, Yiftach (2019)."Thought Experiments".Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 21 November 2017. Retrieved29 October 2021.
Casati, Filippo; Fujikawa, Naoya."Existence".Internet Encyclopedia of Philosophy.ISSN2161-0002.Archived from the original on 10 August 2023. Retrieved7 August 2023.
Chakravartty, Anjan (2017)."Scientific Realism".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 30 April 2019. Retrieved2 June 2024.
Chalmers, David (2009). "Ontological Anti-Realism". In Chalmers, David; Manley, David; Wasserman, Ryan (eds.).Metametaphysics: New Essays on the Foundations of Ontology. Oxford University Press.ISBN978-0-19-954604-6.
Dalal, Neil (2021)."Śaṅkara".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 27 January 2022. Retrieved2 April 2024.
Daly, Chris (2009)."To Be". In Poidevin, Robin Le; Peter, Simons; Andrew, McGonigal; Cameron, Ross P. (eds.).The Routledge Companion to Metaphysics. Routledge.ISBN978-1-134-15585-9.Archived from the original on 17 August 2023. Retrieved1 September 2023.
DeLapp, Kevin M."Metaethics".Internet Encyclopedia of Philosophy.Archived from the original on January 23, 2024. Retrieved19 December 2023.
Desmet, Ronald; Irvine, Andrew David (2022)."Alfred North Whitehead".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University. Retrieved1 April 2024.
Dynes, Wayne R. (2016)."Creation of Daoism (6th Century BC)". In Curta, Florin; Holt, Andrew (eds.).Great Events in Religion: An Encyclopedia of Pivotal Events in Religious History. Bloomsbury Publishing USA.ISBN978-1-61069-566-4.Archived from the original on 30 March 2024. Retrieved4 April 2024.
Effingham, Nikk (2013).Introduction to Ontology. Polity Press.ISBN978-0-7456-5254-2.
Epstein, Brian (2024)."Social Ontology".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University. Retrieved18 June 2024.
Falguera, José L.; Martínez-Vidal, Concha; Rosen, Gideon (2022)."Abstract Objects".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 22 January 2021. Retrieved12 August 2023.
Faye, Jan (2013)."Is Time an Abstract Entity?". In Stadler, Friedrich; Stöltzner, Michael (eds.).Time and History: Proceedings of the 28. International Ludwig Wittgenstein Symposium, Kirchberg am Wechsel, Austria 2005. Walter de Gruyter.ISBN978-3-11-033321-3.Archived from the original on 13 August 2023. Retrieved1 September 2023.
Fernández-López, Mariano; Gómez-Pérez, Asunción (2002). "Overview and Analysis of Methodologies for Building Ontologies".The Knowledge Engineering Review.17 (2):129–156.doi:10.1017/S0269888902000462.
Fine, Kit (1995). "Ontological Dependence".Proceedings of the Aristotelian Society.95 (1):269–290.doi:10.1093/aristotelian/95.1.269.
Gallois, Andre (2016)."Identity Over Time".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University. Retrieved28 March 2024.
Garcia-Godinez, Miguel (2023)."Easy Social Ontology". In Garcia-Godinez, Miguel (ed.).Thomasson on Ontology. Springer Nature.ISBN978-3-031-23672-3.Archived from the original on 2024-06-13. Retrieved2024-06-17.
Goris, Wouter; Aertsen, Jan (2019)."Medieval Theories of Transcendentals".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved22 June 2024.
Gowans, Chris (2021)."Moral Relativism".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on February 1, 2024. Retrieved19 December 2023.
Graham, Jacob."Presocratics".Internet Encyclopedia of Philosophy.Archived from the original on 9 February 2021. Retrieved21 June 2024.
Grenon, Pierre (2008). "A Primer on Knowledge Management and Ontological Engineering". In Munn, Katherine; Smith, Barry (eds.).Applied Ontology: An Introduction. Ontos Verlag.ISBN978-3-938793-98-5.
Grier, Michelle (2022)."Kant's Critique of Metaphysics".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved25 June 2024.
Hancock, Roger (2006). "Metaphysics, History of". In Borchert, Donald M. (ed.).The Encyclopedia of Philosophy. 6: Masaryk – Nussbaum (2 ed.). Thomson Gale, Macmillan Reference.ISBN978-0-02-865786-8.
Hawley, Katherine (2023)."Temporal Parts".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved26 March 2024.
Hennig, Boris (2008). "What Is Formal Ontology?". In Munn, Katherine; Smith, Barry (eds.).Applied Ontology: An Introduction. Ontos Verlag.ISBN978-3-938793-98-5.
Hettche, Matt; Dyck, Corey (2019)."Christian Wolff".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 8 August 2019. Retrieved2 April 2024.
Hofweber, Thomas (2023)."Logic and Ontology".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 7 December 2021. Retrieved31 May 2024.
Jacob, Pierre (2023)."Intentionality".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on August 29, 2018. Retrieved28 April 2024.
Kirk, Robert (2023)."Zombies".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 28 September 2020. Retrieved15 March 2024.
Klement, Kevin (2019)."Russell's Logical Atomism".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 11 April 2024. Retrieved2 April 2024.
Koons, Robert C.; Pickavance, Timothy H. (2015).Metaphysics: The Fundamentals (1 ed.). Wiley-Blackwell.ISBN978-1-4051-9574-4.
Kozierkiewicz, Adrianna; Pietranik, Marcin (2019)."A Formal Framework for the Ontology Evolution". In Nguyen, Ngoc Thanh; Gaol, Ford Lumban; Hong, Tzung-Pei; Trawiński, Bogdan (eds.).Intelligent Information and Database Systems: 11th Asian Conference, ACIIDS 2019, Yogyakarta, Indonesia, April 8–11, 2019, Proceedings, Part I. Springer.ISBN978-3-030-14799-0.
Kroon, Fred; Voltolini, Alberto (2023)."Fictional Entities".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on June 17, 2024. Retrieved28 April 2024.
Kuhlmann, Meinard (2010). "Ontologie". In Sandkühler, Hans Jörg (ed.).Enzyklopädie Philosophie (2 ed.). Meiner.ISBN978-3-7873-1999-2.
Kuhn, Thomas S. (2010)."Possible Worlds in History of Science". In Sture, Allén (ed.).Possible Worlds in Humanities, Arts and Sciences: Proceedings of Nobel Symposium 65. Walter de Gruyter.ISBN978-3-11-086685-8.Archived from the original on 28 March 2024. Retrieved29 March 2024.
Ladyman, James (2023)."Structural Realism".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 11 September 2019. Retrieved5 June 2024.
Lehrer, Keith (1993)."Preface". In Lehrer, Keith (ed.).Haecceity: An Ontological Essay. Springer Science & Business Media.ISBN978-0-7923-2438-6.Archived from the original on 2024-06-19. Retrieved2024-06-20.
Leuenberger, Stephan (2017)."Wolff's Close Shafe with Fatalism". In Sinclair, Mark (ed.).The Actual and the Possible: Modality and Metaphysics in Modern Philosophy. Oxford University Press.ISBN978-0-19-108973-2.Archived from the original on 2024-06-16. Retrieved2024-06-17.
Linnebo, Øystein (2024)."Platonism in the Philosophy of Mathematics".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 25 November 2018. Retrieved2 June 2024.
Littlejohn, Ronnie."Daoist Philosophy".Internet Encyclopedia of Philosophy.Archived from the original on 29 March 2024. Retrieved30 March 2024.
Lizzini, Olga (2021)."Ibn Sina's Metaphysics".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 11 April 2024. Retrieved23 June 2024.
Look, Brandon C. (2020)."Gottfried Wilhelm Leibniz".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 5 August 2020. Retrieved2 April 2024.
Lopez, Carlos (2010)."India, Hinduism in: Medieval Period". In Melton, J. Gordon; Baumann, Martin (eds.).Religions of the World: A Comprehensive Encyclopedia of Beliefs and Practices. Bloomsbury.ISBN978-1-59884-204-3.Archived from the original on 2024-07-06. Retrieved2024-06-26.
Ludwig, David; Weiskopf, Daniel A. (2019)."Ethnoontology: Ways of World-building Across Cultures".Philosophy Compass.14 (9).doi:10.1111/phc3.12621.S2CID199516840.Consider the animism debate. Animists consider nonhuman entities (e.g., plants, forests, or rivers) as intentional actors (Harvey, 2005). There is substantial evidence that animism is a widespread metaphysical view. For example, the Nayaka people of South India consider not only certain animals but also stones, hills, cups, and knives to be devaru: beings that stand in active, quasi-social relationships with them (Bird-David, 1999). Devaru are aspects of a larger kin structure that incorporates potential "partners" in the nonhuman world. In addition to these ethnographic observations, there are intriguing cross-cultural similarities in animist ontologies. Indigenous communities around the world tend to be much more permissive in their ascription of intentionality than Western participants (Ojalehto, Douglas, & García, 2017).
MacBride, Fraser (2020)."Relations".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved2 July 2024.
MacIntyre, Alasdair (2006). "Being". In Borchert, Donald M. (ed.).Encyclopedia of Philosophy. Vol. 1 (2 ed.). Macmillan Reference USA.ISBN978-0-02-865781-3.
Mackie, Penelope (1998)."Existence".Routledge Encyclopedia of Philosophy. Routledge.ISSN2161-0002.Archived from the original on 10 August 2023. Retrieved7 August 2023.
MacLeod, Mary C.; Rubenstein, Eric M."Universals".Internet Encyclopedia of Philosophy.Archived from the original on 24 February 2024. Retrieved24 March 2024.
Marshall, Dan; Weatherson, Brian (2023)."Intrinsic Vs. Extrinsic Properties".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved2 July 2024.
McLaughlin, Brian P. (1999). Audi, Robert (ed.).The Cambridge Dictionary of Philosophy (2 ed.). Cambridge University Press.ISBN978-0-521-63722-0.
Menzel, Christopher (2023)."Possible Worlds".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved24 March 2024.
Merriam-Webster (2024)."Definition of Ontology".Merriam-Webster Dictionary. Merriam-Webster.Archived from the original on 6 July 2018. Retrieved17 June 2024.
Mulligan, Kevin (2012)."Preface". In Mulligan, Kevin (ed.).Language, Truth and Ontology. Springer Science & Business Media.ISBN978-94-011-2602-1.Archived from the original on 2024-06-17. Retrieved2024-06-18.
Mumford, Stephen (2012).Metaphysics: A Very Short Introduction (1 ed.). Oxford University Press.ISBN978-0-19-965712-4.
Nelson, Michael (2022)."Existence".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 3 September 2018. Retrieved6 August 2023.
Niiniluoto, Ilkka (2002).Critical Scientific Realism. Oxford University Press.ISBN978-0-19-159809-8.
Noonan, Harold; Curtis, Ben (2022)."Identity".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 23 July 2020. Retrieved28 March 2024.
Orilia, Francesco; Paolini Paoletti, Michele (2022)."Properties".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 16 April 2024. Retrieved2 July 2024.
O’Madagain, Cathal."Intentionality".Internet Encyclopedia of Philosophy.ISSN2161-0002.Archived from the original on April 28, 2024. Retrieved28 April 2024.
Parent, Ted."Modal Metaphysics".Internet Encyclopedia of Philosophy.Archived from the original on 11 November 2020. Retrieved22 March 2024.
Paul, L. A. (2017). "A One Category Ontology". In Keller, John A. (ed.).Being, Freedom, and Method: Themes from the Philosophy of Peter Van Inwagen. Oxford University Press.ISBN978-0-19-871570-2.
Peterson, Keith; Poli, Roberto (2022)."Nicolai Hartmann".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved25 June 2024.
Phillips, R. L. (1967). "Descriptive Versus Revisionary Metaphysics and the Mind–Body Problem".Philosophy.42 (160):105–118.doi:10.1017/S0031819100001030.
Plebani, Matteo (2013)."Introduction". In Camposampiero, Favaretti Matteo; Plebani, Matteo (eds.).Existence and Nature: New Perspectives. Walter de Gruyter.ISBN978-3-11-032180-7.Archived from the original on 20 August 2023. Retrieved1 September 2023.
Poli, Roberto (2011). "Hartmann's Theory of Categories: Introductory Remarks". In Poli, Roberto; Scognamiglio, Carlo; Tremblay, Frederic (eds.).The Philosophy of Nicolai Hartmann. Walter de Gruyter.ISBN978-3-11-025418-1.
Prior, A. N. (2006). "Existence". In Borchert, Donald (ed.).Encyclopedia of Philosophy. Vol. 3 (2nd ed.). Macmillan Reference USA.ISBN978-0-02-865790-5.
Proops, Ian (2022)."Wittgenstein's Logical Atomism".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved2 April 2024.
Rae, Gavin (2014). "Traces of Identity In Deleuze's Differential Ontology".International Journal of Philosophical Studies.22 (1):86–105.doi:10.1080/09672559.2013.861003.
Rea, Michael Cannon (1997)."Introduction". In Rea, Michael Cannon (ed.).Material Constitution: A Reader. Rowman & Littlefield.ISBN978-0-8476-8384-0.Archived from the original on 2024-07-06. Retrieved2024-07-03.
Rea, Michael C. (2021).Metaphysics: The Basics (2 ed.). Routledge.ISBN978-0-367-13607-9.
Redding, Paul (2020)."Georg Wilhelm Friedrich Hegel".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 30 April 2019. Retrieved24 June 2024.
Reicher, Maria (2022)."Nonexistent Objects".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 1 February 2024. Retrieved10 August 2023.
Rettler, Bradley; Bailey, Andrew M. (2023)."Object".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 16 June 2022. Retrieved9 June 2024.
Robinet, Isabelle (2013)."Chongxuan". In Pregadio, Fabrizio (ed.).The Encyclopedia of Taoism. Routledge.ISBN978-1-135-79634-1.Archived from the original on 2 April 2024. Retrieved4 April 2024.
Robinson, Howard (2004). "Thought Experiments, Ontology, and Concept-Dependent Truthmakers".Monist.87 (4):537–553.doi:10.5840/monist200487422.
Robinson, Howard (2023)."Dualism".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 7 November 2023. Retrieved9 June 2024.
Robinson, Howard; Weir, Ralph (2024)."Substance".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University. Retrieved5 June 2024.
Sadegh-Zadeh, Kazem (2011)."Fuzzy Formal Ontology". In Seising, Rudolf; González, Veronica Sanz (eds.).Soft Computing in Humanities and Social Sciences. Springer.ISBN978-3-642-24672-2.Archived from the original on 2024-06-18. Retrieved2024-06-20.
Sayre-McCord, Geoff (2023a)."Moral Realism".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on April 23, 2020. Retrieved19 December 2023.
Schaffer, Jonathan (2009). "On What Grounds What". In Chalmers, David; Manley, David; Wasserman, Ryan (eds.).Metametaphysics: New Essays on the Foundations of Ontology. Oxford University Press.ISBN978-0-19-954604-6.
Schaffer, Jonathan (2010). "Monism: The Priority of the Whole".The Philosophical Review.119 (1):31–76.doi:10.1215/00318108-2009-025.
Schaffer, Jonathan (2018)."Monism".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved9 June 2024.
Scott, Michael W. (2013)."The Anthropology of Ontology (Religious Science?)".The Journal of the Royal Anthropological Institute.19 (4):859–872.doi:10.1111/1467-9655.12067.JSTOR42001687.Archived from the original on 2022-09-24. Retrieved2022-09-24.Since roughly the 1990s, a growing number of anthropologists have become interested in the study of ontology – the investigation and theorization of diverse experiences and understandings of the nature of being itself. This generally takes the form of ethnographic accounts of indigenous non-Western modes and models of being, presented in more or less explicit contrast with aspects of a Euro-American or modern ontology imputed to conventional anthropology.
Sider, Theodore (2009). "Ontological Realism". In Chalmers, David; Manley, David; Wasserman, Ryan (eds.).Metametaphysics: New Essays on the Foundations of Ontology. Oxford University Press.ISBN978-0-19-954604-6.
Smith, Barry; Klagges, Bert (2008). "Philosophy and Biomedical Information Systems". In Munn, Katherine; Smith, Barry (eds.).Applied Ontology: An Introduction. Ontos Verlag.ISBN978-3-938793-98-5.
Sorensen, Roy (2023)."Nothingness".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 30 August 2006. Retrieved17 August 2023.
Sprigge, T. L. S. (1998)."Idealism".Routledge Encyclopedia of Philosophy. Routledge.Archived from the original on 4 November 2019. Retrieved9 June 2024.
Stubenberg, Leopold; Wishon, Donovan (2023)."Neutral Monism".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 15 July 2018. Retrieved27 March 2024.
Studtmann, Paul (2024)."Aristotle's Categories".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved22 March 2024.
Tahko, Tuomas E. (2015).An Introduction to Metametaphysics. Cambridge University Press.ISBN978-1-107-07729-4.
Tahko, Tuomas E.; Lowe, E. Jonathan (2020)."Ontological Dependence".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 July 2024. Retrieved2 July 2024.
Tambassi, Timothy (2022)."The Riddle of Reality". In Tambassi, Timothy (ed.).Studies in the Ontology of E. J. Lowe. Taylor & Francis.ISBN978-3-86838-213-6.Archived from the original on 2024-07-06. Retrieved2024-06-18.
Textor, Mark (2021)."States of Affairs".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 11 June 2018. Retrieved3 July 2024.
Thomasson, Amie L. (2012). "Experimental Philosophy and the Methods of Ontology".Monist.95 (2):175–199.doi:10.5840/monist201295211.
Thomasson, Amie (2022)."Categories".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 8 October 2023. Retrieved20 March 2024.
Thompson, Kirill (2021)."Zhu Xi".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University. Retrieved6 July 2024.
Thomson, Ian (2011)."Ontotheology". In Dahlstrom, Daniel O. (ed.).Interpreting Heidegger: Critical Essays. Cambridge University Press.ISBN978-1-139-50042-5.Archived from the original on 2024-06-28. Retrieved2024-06-29.
Vaidya, Anand Jayprakash; Wallner, Michale (2024)."Conferralism;". In Koslicki, Kathrin; Raven, Michael J. (eds.).The Routledge Handbook of Essence in Philosophy. Taylor & Francis.ISBN978-1-040-01688-6.Archived from the original on 2024-07-06. Retrieved2024-07-03.
Van Inwagen, Peter (2011). "Relational Vs. Constituent Ontologies".Philosophical Perspectives.25 (1):389–405.doi:10.1111/j.1520-8583.2011.00221.x.
Van Inwagen, Peter (2023)."Existence".Encyclopædia Britannica.Archived from the original on 29 June 2023. Retrieved7 August 2023.
Van Inwagen, Peter; Sullivan, Meghan; Bernstein, Sara (2023)."Metaphysics".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 16 September 2018. Retrieved17 March 2024.
Varzi, Achille (2019)."Mereology".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 28 September 2020. Retrieved25 March 2024.
Weir, Alan (2024)."Formalism in the Philosophy of Mathematics".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 1 February 2024. Retrieved2 June 2024.
Westacott, Emrys."Moral Relativism".Internet Encyclopedia of Philosophy.Archived from the original on December 16, 2023. Retrieved19 December 2023.
Wheeler, Michael (2020)."Martin Heidegger".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 6 February 2022. Retrieved19 June 2024.
Widder, Nathan (2009)."John Duns Scotus". In Jones, Graham (ed.).Deleuze's Philosophical Lineage. Edinburgh University Press.ISBN978-0-7486-3195-7.Archived from the original on 2024-07-06. Retrieved2024-07-03.
Williams, Thomas (2022)."John Duns Scotus".The Stanford Encyclopedia of Philosophy. Metaphysics Research Lab, Stanford University.Archived from the original on 11 June 2017. Retrieved25 June 2024.
Wittgenstein, Ludwig (2001) [1921].Tractatus Logico-philosophicus. Translated by Pears, David; McGuinness, Brian. Routledge.ISBN978-0-415-25562-2.
Woznicki, Christopher Grzegorz (2022).T. F. Torrance's Christological Anthropology: Discerning Humanity in Christ. Routledge.ISBN978-1-032-20134-4.
.jpg)
.png)
