Direct and indirect realism

Last updated
Direct realism argues we perceive the world directly Naive realism.jpg
Direct realism argues we perceive the world directly

The question of direct or naïve realism, as opposed to indirect or representational realism, arises in the philosophy of perception and of mind out of the debate over the nature of conscious experience; [1] [2] the epistemological question of whether the world we see around us is the real world itself or merely an internal perceptual copy of that world generated by neural processes in our brain.

Philosophy of perception

The philosophy of perception is concerned with the nature of perceptual experience and the status of perceptual data, in particular how they relate to beliefs about, or knowledge of, the world. Any explicit account of perception requires a commitment to one of a variety of ontological or metaphysical views. Philosophers distinguish internalist accounts, which assume that perceptions of objects, and knowledge or beliefs about them, are aspects of an individual's mind, and externalist accounts, which state that they constitute real aspects of the world external to the individual. The position of naïve realism—the 'everyday' impression of physical objects constituting what is perceived—is to some extent contradicted by the occurrence of perceptual illusions and hallucinations and the relativity of perceptual experience as well as certain insights in science. Realist conceptions include phenomenalism and direct and indirect realism. Anti-realist conceptions include idealism and skepticism.

Philosophy of mind branch of philosophy on the nature of the mind

Philosophy of mind is a branch of philosophy that studies the ontology, nature, and relationship of the mind to the body. The mind–body problem is a paradigm issue in philosophy of mind, although other issues are addressed, such as the hard problem of consciousness, and the nature of particular mental states. Aspects of the mind that are studied include mental events, mental functions, mental properties, consciousness, the ontology of the mind, the nature of thought, and the relationship of the mind to the body.

Consciousness state or quality of awareness or of being aware of an external object or something within oneself

Consciousness is the state or quality of awareness or of being aware of an external object or something within oneself. It has been defined variously in terms of sentience, awareness, qualia, subjectivity, the ability to experience or to feel, wakefulness, having a sense of selfhood or soul, the fact that there is something "that it is like" to "have" or "be" it, and the executive control system of the mind. Despite the difficulty in definition, many philosophers believe that there is a broadly shared underlying intuition about what consciousness is. As Max Velmans and Susan Schneider wrote in The Blackwell Companion to Consciousness: "Anything that we are aware of at a given moment forms part of our consciousness, making conscious experience at once the most familiar and most mysterious aspect of our lives."


Naïve realism is known as direct realism when developed to counter indirect or representative realism, also known as epistemological dualism, [3] the philosophical position that our conscious experience is not of the real world itself but of an internal representation, a miniature virtual-reality replica of the world.

Naïve realism philosophical theory of mind

In philosophy of mind, naïve realism, also known as direct realism, common sense realism or perceptual realism, is the idea that the senses provide us with direct awareness of objects as they really are. Objects obey the laws of physics and retain all their properties whether or not there is anyone to observe them. They are composed of matter, occupy space and have properties, such as size, shape, texture, smell, taste and colour, that are usually perceived correctly.

A mental representation, in philosophy of mind, cognitive psychology, neuroscience, and cognitive science, is a hypothetical internal cognitive symbol that represents external reality, or else a mental process that makes use of such a symbol: "a formal system for making explicit certain entities or types of information, together with a specification of how the system does this".

Virtual reality Computer-simulated environment simulating physical presence in real or imagined worlds

Virtual reality (VR) is an interactive computer-generated experience taking place within a simulated environment. It incorporates mainly auditory and visual feedback, but may also allow other types of sensory feedback. This immersive environment can be similar to the real world or it can be fantastical.

Indirect realism is broadly equivalent to the accepted view of perception in natural science that states that we do not and cannot perceive the external world as it really is but know only our ideas and interpretations of the way the world is. [4] Representationalism is one of the key assumptions of cognitivism in psychology. The representational realist would deny that "first-hand knowledge" is a coherent concept, since knowledge is always via some means. Our ideas of the world are interpretations of sensory input derived from an external world that is real (unlike the standpoint of idealism, which holds that only ideas are real, but mind-independent things are not).

Perception organization, identification, and interpretation of sensory information in order to represent and understand the environment

Perception is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information, or the environment.

In psychology, cognitivism is a theoretical framework for understanding the mind that gained credence in the 1950s. The movement was a response to behaviorism, which cognitivists said neglected to explain cognition. Cognitive psychology derived its name from the Latin cognoscere, referring to knowing and information, thus cognitive psychology is an information-processing psychology derived in part from earlier traditions of the investigation of thought and problem solving.

Psychology is the science of behavior and mind. Psychology includes the study of conscious and unconscious phenomena, as well as feeling and thought. It is an academic discipline of immense scope. Psychologists seek an understanding of the emergent properties of brains, and all the variety of phenomena linked to those emergent properties. As a social science it aims to understand individuals and groups by establishing general principles and researching specific cases.

The main alternative to representationalism is anti-representationalism, the view according to which perception is not a process of constructing internal representations.


Aristotle was the first to provide a description of direct realism. In On the Soul he describes how a see-er is informed of the object itself by way of the hylomorphic form carried over the intervening material continuum with which the eye is impressed. [5]

Aristotle philosopher in ancient Greece

Aristotle was a philosopher during the Classical period in Ancient Greece, the founder of the Lyceum and the Peripatetic school of philosophy and Aristotelian tradition. Along with his teacher Plato, he is considered the "Father of Western Philosophy". His writings cover many subjects – including physics, biology, zoology, metaphysics, logic, ethics, aesthetics, poetry, theatre, music, rhetoric, psychology, linguistics, economics, politics and government. Aristotle provided a complex synthesis of the various philosophies existing prior to him, and it was above all from his teachings that the West inherited its intellectual lexicon, as well as problems and methods of inquiry. As a result, his philosophy has exerted a unique influence on almost every form of knowledge in the West and it continues to be a subject of contemporary philosophical discussion.

<i>On the Soul</i> Treatise by Aristotle

On the Soul is a major treatise written by Aristotle c. 350 BC. Although its topic is the soul, it is not about spirituality but rather a work in what might best be described as biopsychology, a description of the subject of psychology within a biological framework. His discussion centres on the kinds of souls possessed by different kinds of living things, distinguished by their different operations. Thus plants have the capacity for nourishment and reproduction, the minimum that must be possessed by any kind of living organism. Lower animals have, in addition, the powers of sense-perception and self-motion (action). Humans have all these as well as intellect.

Substance theory, or substance–attribute theory, is an ontological theory about objecthood positing that a substance is distinct from its properties. A thing-in-itself is a property-bearer that must be distinguished from the properties it bears.

In medieval philosophy, direct realism was defended by Thomas Aquinas. [5]

Medieval philosophy

Medieval philosophy is a term used to refer to the philosophy that existed through the Middle Ages, the period roughly extending from the fall of the Western Roman Empire in the 5th century to the Renaissance in the 15th century. Medieval philosophy, understood as a project of independent philosophical inquiry, began in Baghdad, in the middle of the 8th century, and in France, in the itinerant court of Charlemagne, in the last quarter of the 8th century. It is defined partly by the process of rediscovering the ancient culture developed in Greece and Rome during the Classical period, and partly by the need to address theological problems and to integrate sacred doctrine with secular learning.

Thomas Aquinas Dominican scholastic philosopher of the Roman Catholic Church

Saint Thomas Aquinas was an Italian Dominican friar, Catholic priest, and Doctor of the Church. He is an immensely influential philosopher, theologian, and jurist in the tradition of scholasticism, within which he is also known as the Doctor Angelicus and the Doctor Communis. The name Aquinas identifies his ancestral origins in the county of Aquino in present-day Lazio, Italy.

Indirect realism was popular with several early modern philosophers, including René Descartes, [6] John Locke, [6] G. W. Leibniz, [7] George Berkeley, [8] and David Hume. [8]

Early modern philosophy

Early modern philosophy is a period in the history of philosophy at the beginning or overlapping with the period known as modern philosophy.

René Descartes 17th-century French philosopher, mathematician, and scientist

René Descartes was a French philosopher, mathematician, and scientist. A native of the Kingdom of France, he spent about 20 years (1629–1649) of his life in the Dutch Republic after serving for a while in the Dutch States Army of Maurice of Nassau, Prince of Orange and the Stadtholder of the United Provinces. He is generally considered one of the most notable intellectual figures of the Dutch Golden Age.

John Locke English philosopher and physician

John Locke was an English philosopher and physician, widely regarded as one of the most influential of Enlightenment thinkers and commonly known as the "Father of Liberalism". Considered one of the first of the British empiricists, following the tradition of Sir Francis Bacon, he is equally important to social contract theory. His work greatly affected the development of epistemology and political philosophy. His writings influenced Voltaire and Jean-Jacques Rousseau, many Scottish Enlightenment thinkers, as well as the American revolutionaries. His contributions to classical republicanism and liberal theory are reflected in the United States Declaration of Independence.

Locke categorized qualities as follows: [9]

Thomas Reid, a notable member of the Scottish common sense realism was a proponent of direct realism. [10] Direct realist views have been attributed to Baruch Spinoza. [11] Immanuel Kant's empirical realism has also been interpreted as a form of direct realism. [12]

Late modern philosophers, J. G. Fichte and G. W. F. Hegel followed Kant in adopting empirical realism. [13] [14] On the other hand, Gottlob Frege (in his paper "Über Sinn und Bedeutung") subscribed to indirect realism. [15]

In contemporary philosophy, indirect realism has been defended by Edmund Husserl [16] and Bertrand Russell [8] Direct realism has been defended by Hilary Putnam, [17] John McDowell, [18] [19] Galen Strawson, [20] and John R. Searle. [21]

However, epistemological dualism has come under sustained attack by other contemporary philosophers, such as Ludwig Wittgenstein (the private language argument) and Wilfrid Sellars in his seminal essay "Empiricism and the Philosophy of Mind". Indirect realism is argued to be problematical because of Ryle's regress and the homunculus argument. Recently, reliance on the private language argument and the "homunculus objection" has itself come under attack. It can be argued that those who argue for "inner presence", to use Antti Revonsuo's term, [22] are not proposing a private "referent", with the application of language to it being "private" and thus unshareable, but a private use of public language. There is no doubt that each of us has a private understanding of public language, a notion that has been experimentally supported; [23] George Steiner refers to our personal use of language as an "idiolect", one particular to ourselves in its detail. [24] The question has to be put how a collective use of language can go on when, not only do we have differing understandings of the words we use, but our sensory registrations differ. [25]

Problems with the indirect theory

A problem with representationalism is that if simple data flow and information processing is assumed then something in the brain must be interpreting incoming data as a "percept". This something is often described as a homunculus, although the term homunculus is also used to imply an entity that creates a continual regress, and this need not be implied. This suggests that some phenomenon other than simple data flow and information processing is involved in perception. This is more of an issue now than it was for rationalist philosophers prior to Newton, such as Descartes, for whom physical processes were poorly defined. Descartes held that there is a "homunculus" in the form of the soul, belonging to a form of natural substance known as res cogitans that obeyed different laws from those obeyed by solid matter ( res extensa ). Although Descartes' duality of natural substances may have echoes in modern physics (Bose and Fermi statistics) no agreed account of 'interpretation' has been formulated. Thus representationalism remains an incomplete description of perception. Aristotle realized this and simply proposed that ideas themselves (representations) must be aware—in other words that there is no further transfer of sense impressions beyond ideas.

The representational theory of perception Rep-perception.jpg
The representational theory of perception

A potential difficulty with representational realism is that, if we only have knowledge of representations of the world, how can we know that they resemble in any significant way the objects to which they are supposed to correspond? Any creature with a representation in its brain would need to interact with the objects that are represented to identify them with the representation. This difficulty would seem reasonably to be covered by the learning by exploration of the world that goes on throughout life. However, there may still be a concern that if the external world is only to be inferred, its 'true likeness' might be quite different from our idea of it. The representational realist would answer to this that "true likeness" is an intuitive concept that falls in the face of logic, since a likeness must always depend on the way in which something is considered.

A semantic difficulty may arise when considering reference in representationalism. If a person says "I see the Eiffel Tower" at a time when they are indeed looking at the Eiffel Tower, to what does the term "Eiffel Tower" refer? The direct realist might say that in the representational account people do not really see the tower but rather 'see' the representation. However, this is a distortion of the meaning of the word see which the representationalist does not imply. For the representationalist the statement refers to the Eiffel Tower, which implicitly is experienced in the form of a representation. The representationalist does not imply that when a person refers to the Eiffel Tower, they are referring to their sense experience, and when another person refers to the Tower, they are referring to their sense experience.

Furthermore, representative realism claims that we perceive our perceptual intermediaries-we can attend to them-just as we observe our image in a mirror. However, as we can scientifically verify, this is clearly not true of the physiological components of the perceptual process. This also brings up the problem of dualism and its relation to representative realism, concerning the incongruous marriage of the metaphysical and the physical.

The new objection to the Homunculus Argument claims that it relies on a naive view of sensation. Because the eyes respond to light rays is no reason for supposing that the visual field requires eyes to see it. Visual sensation (the argument can be extrapolated to the other senses) bears no direct resemblance to the light rays at the retina, nor to the character of what they are reflected from or pass through or what was glowing at the origin of them. The reason given is that they only bear the similarities of co-variation with what arrives at the retinas. [26] Just as the currents in a wire going to a loudspeaker vary proportionately with the sounds that emanate from it but have no other likeness, so too does sensation vary proportionately (and not necessarily directly) with what causes it but bears no other resemblance to the input. This implies that the colour we experience is actually a cortical occurrence, and that light rays and external surfaces are not themselves coloured. The proportional variations with which cortical colour changes are there in the external world, but not colour as we experience it. Contrary to what Gilbert Ryle believed, those who argue for sensations being brain processes do not have to hold that there is a "picture" in the brain since this is impossible according to this theory since actual pictures in the external world are not coloured. [27] It is plain that Ryle unthinkingly carried over what the eyes do to the nature of sensation; A. J. Ayer at the time described Ryle's position as "very weak". [28] So there is no "screen" in front of cortical "eyes", no mental objects before one. As Thomas Hobbes put it: "How do we take notice of sense?—by sense itself". Moreland Perkins has characterized it thus: that sensing is not like kicking a ball, but rather "kicking a kick". [29] Today there are still philosophers arguing for colour being a property of external surfaces, light sources, etc. [30]

A more fundamental criticism is implied in theories of this type. The differences at the sensory and perceptual levels between agents require that some means of ensuring at least a partial correlation can be achieved that allows the updatings involved in communication to take place. The process in an informative statement begins with the parties hypothetically assuming that they are referring to the "same" entity or "property", even though their selections from their sensory fields cannot match; we can call this mutually imagined projection the "logical subject" of the statement. The speaker then produces the logical predicate which effects the proposed updating of the "referent". If the statement goes through, the hearer will now have a different percept and concept of the "referent"—perhaps even seeing it now as two things and not one. The radical conclusion is that we are premature in conceiving of the external as already sorted into singular "objects" in the first place, since we only need to behave as if they are already logically singular. [31] The diagram at the beginning of this entry would thus be thought of as a false picture of the actual case, since to draw "an" object as already selected from the real is only to treat the practically needful, but strictly false, hypothesis of objects-as-logically-singular as ontologically given. The proponents of this view thus argue that there is no need actually to believe in the singularity of an object since we can manage perfectly well by mutually imagining that 'it' is singular. A proponent of this theory can thus ask the direct realist feels why he or she thinks it is necessary to move to taking the imagining of singularity for real when there is no practical difference in the outcome in action. Therefore, although there are selections from our sensory fields which for the time being we treat as if they were objects, they are only provisional, open to corrections at any time, and, hence, far from being direct representations of pre-existing singularities, they retain an experimental character. Virtual constructs or no, they remain, however, selections that are causally linked to the real and can surprise us at any time—which removes any danger of solipsism in this theory. This approach dovetails with the philosophy known as social constructivism. [32]

The character of experience of a physical object can be altered in major ways by changes in the conditions of perception or of the relevant sense-organs and the resulting neurophysiological processes, without change in the external physical object that initiates this process and that may seem to be depicted by the experience. Conversely any process that yields the same sensory/neural results will yield the same perceptual experience, no matter what the physical object that initiated the process may have been like. Furthermore, the causal process that intervenes between the external object and the perceptual experience takes time, so that the character of the experience reflects, at the most, an earlier stage of that object than the one existing at the moment of perception. As in observations of astronomical objects the external object may have ceased to exist long before the experience occurs. These facts are claimed to point to the conclusion that the direct object of experience is an entity produced at the end of this causal process, distinct from any physical object that initiates the process." [33]

The adverbial theory

The above argument invites the conclusion of a perceptual dualism that raises the issue of how and whether the object can be known by experience. The adverbial theory proposes "that this dualism is a dualism of objects, with perceptual experience being a more direct experience of objects of a different sort, sense-data." [33] Perceptual dualism implies:

both an act of awareness (or apprehension) and an object (the sense-datum) which that act apprehends or is an awareness of. The fundamental idea of the adverbial theory, in contrast, is that there is no need for such objects and the problems that they bring with them (such as whether they are physical or mental or somehow neither). Instead, it is suggested, merely the occurrence of a mental act or mental state with its own intrinsic character is enough to account for the character of immediate experience. [33]

According to the adverbial theory, when, for example, I experience a silver elliptical shape (as when viewing a coin from an angle) I am in a certain specific state of sensing or sensory awareness or of being appeared to: I sense in a certain manner or am appeared to in a certain way, and that specific manner of sensing or of being appeared to accounts for the content of my experience: I am in a certain distinctive sort of experiential state. There need be no object or entity of any sort that is literally silver and elliptical in the material world or in the mind. I experience a silver and elliptical shape because an object or entity that literally has that color and shape is directly before my mind. But the nature of these entities and the way in which they are related to the mind are difficult to understand. The adverbial theory has the advantage of being metaphysically simpler, avoiding issues about the nature of sense-data, but we gain no real understanding of the nature of the states in question or of how exactly they account for the character of immediate experience." [33]

Arguments against direct realism

The argument from illusion

Illusion creates a problem for naive realists as it suggests our senses are fallible, perceiving things that aren't there. In this illusion, the lines are horizontal, despite how they appear. Cafe wall.svg
Illusion creates a problem for naïve realists as it suggests our senses are fallible, perceiving things that aren't there. In this illusion, the lines are horizontal, despite how they appear.

This argument was "first offered in a more or less fully explicit form in Berkeley (1713)." [33] It is also referred to as the problem of conflicting appearances (e.g. Myles Burnyeat's article Conflicting Appearances). It has been argued that "informed commonsense" indicates that perceptions often depend on organs of perception. [34] For example, humans would receive visual information very differently if they, like flies, had compound eyes, and may not even be able to imagine how things would appear with entirely different sense organs such as infra-red detectors or echo-location devices. Furthermore, perception systems can misrepresent objects even when in full working order, as shown, for example, by optical illusions like the Müller-Lyer illusion. More dramatically, sometimes people perceive things which are not there at all, which can be termed instances of "hallucination" or "perceptual delusion". [34]

Illusions are present in nature. Rainbows are an example of a perceptual delusion. "For, unlike an architectural arch, a rainbow recedes as we approach it, never to be reached." Double-alaskan-rainbow.jpg
Illusions are present in nature. Rainbows are an example of a perceptual delusion. "For, unlike an architectural arch, a rainbow recedes as we approach it, never to be reached."

The argument from illusion allegedly shows the need to posit sense-data as the immediate objects of perception. In cases of illusion or hallucination, the object has qualities that no public physical object in that situation has and so must be distinct from any such object. [33] Naïve realism may accommodate these facts as they stand by virtue of its very vagueness (or "open-texture"): it is not specific or detailed enough to be refuted by such cases. [34] A more developed direct realist might respond by showing that various cases of misperception, failed perception, and perceptual relativity do not make it necessary to suppose that sense-data exist. When a stick submerged in water looks bent a direct realist is not compelled to say the stick actually is bent but can say that the stick can have more than one appearance: a straight stick can look bent when light reflected from the stick arrives at one's eye in a crooked pattern, but this appearance is not necessarily a sense-datum in the mind. Similar things can be said about the coin which appears circular from one vantage point and oval-shaped from another. Pressing on your eyeball with a finger creates double vision but assuming the existence of two sense-data is unnecessary: the direct realist can say that they have two eyes, each giving them a different view of the world. Usually the eyes are focused in the same direction; but sometimes they are not.

However, this response is presumably based on previously observed data. If one were to be able to observe nothing other than the stick in the water, with no previous information, it would appear that the stick was bent. Visual depth in particular is a set of inferences, not an actual experience of the space between things in a radial direction outward from the observation point. [36] If all empirical evidence is based upon observation then the entire developed memory and knowledge of every perception and of each sense may be as skewed as the bent stick. Since objects with different qualities are experienced from each of the different perspectives there is no apparent experiential basis for regarding one out of any such set of related perceptual experiences as the one in which the relevant physical object is itself immediately experienced. The most reasonable conclusion is that the experienced object is always distinct from the physical object or at least that there is no way to identify which, if any, of the immediately experienced objects is the physical object itself. Epistemologically it is as though physical objects were never given, whether or not that is in fact the case. [33]

Another potential counter-example involves vivid hallucinations: phantom elephants, for instance, might be interpreted as sense-data. A direct realist response would differentiate hallucination from genuine perception: no perception of elephants is going on, only the different and related mental process of hallucination. However, if there are visual images when we hallucinate it seems reasonable that there are visual images when we see. Similarly if dreaming involves visual and auditory images in our minds it seems reasonable to think there are visual and auditory images, or sense-data, when we are awake and perceiving things. This argument has been challenged in a number of different ways. First it has been questioned whether there must be some object present that actually has the experienced qualities, which would then seemingly have to be something like a sense-datum. Why couldn't it be that the perceiver is simply in a state of seeming to experience such an object without any object actually being present? Second, in cases of illusion and perceptual relativity there is an object present which is simply misperceived, usually in readily explainable ways, and no need to suppose that an additional object is also involved. Third, the last part of the perceptual relativity version of the argument has been challenged by questioning whether there is really no experiential difference between veridical and non-veridical perception; and by arguing that even if sense-data are experienced in non-veridical cases and even if the difference between veridical and non-veridical cases is, as claimed, experientially indiscernible, there is still no reason to think that sense-data are the immediate objects of experience in veridical cases. Fourth, do sense-data exist through time or are they momentary? Can they exist when not being perceived? Are they public or private? Can they be themselves misperceived? Do they exist in minds or are they extra-mental, even if not physical? On the basis of the intractability of these questions, it has been argued that the conclusion of the argument from illusion is unacceptable or even unintelligible, even in the absence of a clear diagnosis of exactly where and how it goes wrong. [33]

Direct realists can potentially deny the existence of any such thing as a mental image but this is difficult to maintain, since we seem able to visually imagine all sorts of things with ease. Even if perception does not involve images other mental processes like imagination certainly seem to. One view, similar to Reid's, is that we do have images of various sorts in our minds when we perceive, dream, hallucinate and imagine but when we actually perceive things, our sensations cannot be considered objects of perception or attention. The only objects of perception are external objects. Even if perception is accompanied by images, or sensations, it is wrong to say we perceive sensations. Direct realism defines perception as perception of external objects where an "external object" is allowed to be a photon in the eye but not an impulse in a nerve leading from the eye. Recent work in neuroscience suggests a shared ontology for perception, imagination and dreaming, with similar areas of brain being used for all of these.

See also

Related Research Articles

In analytic philosophy, anti-realism is an epistemological position first articulated by British philosopher Michael Dummett. The term was coined as an argument against a form of realism Dummett saw as 'colorless reductionism'.

In philosophy, Idealism is the group of metaphysical philosophies that assert that reality, or reality as humans can know it, is fundamentally mental, mentally constructed, or otherwise immaterial. Epistemologically, Idealism manifests as a skepticism about the possibility of knowing any mind-independent thing. In contrast to Materialism, Idealism asserts the primacy of consciousness as the origin and prerequisite of material phenomena. According to this view, consciousness exists before and is the pre-condition of material existence. Consciousness creates and determines the material and not vice versa. Idealism believes consciousness and mind to be the origin of the material world and aims to explain the existing world according to these principles.

Thomas Reid Scottish philosopher

Thomas Reid was a religiously trained Scottish philosopher. He was the founder of the Scottish School of Common Sense and played an integral role in the Scottish Enlightenment. In 1783 he was a joint founder of the Royal Society of Edinburgh. A contemporary of David Hume, Reid was also "Hume's earliest and fiercest critic".

Reality is the sum or aggregate of all that is real or existent, as opposed to that which is merely imaginary. The term is also used to refer to the ontological status of things, indicating their existence. In physical terms, reality is the totality of the universe, known and unknown. Philosophical questions about the nature of reality or existence or being are considered under the rubric of ontology, which is a major branch of metaphysics in the Western philosophical tradition. Ontological questions also feature in diverse branches of philosophy, including the philosophy of science, philosophy of religion, philosophy of mathematics, and philosophical logic. These include questions about whether only physical objects are real, whether reality is fundamentally immaterial, whether hypothetical unobservable entities posited by scientific theories exist, whether God exists, whether numbers and other abstract objects exist, and whether possible worlds exist.

John McDowell South African philosopher and academic

John Henry McDowell is a South African philosopher, formerly a fellow of University College, Oxford and now University Professor at the University of Pittsburgh. Although he has written extensively on metaphysics, epistemology, ancient philosophy, and meta-ethics, McDowell's most influential work has been in the philosophy of mind and philosophy of language. McDowell was one of three recipients of the 2010 Andrew W. Mellon Foundation's Distinguished Achievement Award, and is a Fellow of both the American Academy of Arts & Sciences and the British Academy.

Phenomenalism is the view that physical objects cannot justifiably be said to exist in themselves, but only as perceptual phenomena or sensory stimuli situated in time and in space. In particular, some forms of phenomenalism reduce talk about physical objects in the external world to talk about bundles of sense-data.

Transcendental idealism Epistemology of the 18th-century German philosopher Immanuel Kant. Space and time are merely formal features of how we perceive objects, not things in themselves that exist independently of us.

Transcendental idealism is a doctrine founded by German philosopher Immanuel Kant in the 18th century. Kant's doctrine maintains that human experience of things is similar to the way they appear to us—implying a fundamentally subject-based component, rather than being an activity that directly comprehends the things as they are in themselves. The doctrine is most commonly presented as the idea that time and space are just human perceptions; they are not necessarily real concepts, just a medium through which humans internalize the universe.

In metaphysics, conceptualism is a theory that explains universality of particulars as conceptualized frameworks situated within the thinking mind. Intermediate between nominalism and realism, the conceptualist view approaches the metaphysical concept of universals from a perspective that denies their presence in particulars outside the mind's perception of them. Conceptualism is anti-realist about abstract objects, just like immanent realism is.

In metaphysics, realism about a given object is the view that this object exists in reality independently of our conceptual scheme. In philosophical terms, these objects are ontologically independent of someone's conceptual scheme, perceptions, linguistic practices, beliefs, etc.

In parapsychology, an apparitional experience is an anomalous experience characterized by the apparent perception of either a living being or an inanimate object without there being any material stimulus for such a perception. The person experiencing the apparition is awake, excluding dream visions from consideration.

Anomalous experiences, such as so-called benign hallucinations, may occur in a person in a state of good mental and physical health, even in the apparent absence of a transient trigger factor such as fatigue, intoxication or sensory deprivation.

Disjunctivism is a position in the philosophy of perception that rejects the existence of sense data in certain cases. The disjunction is between appearance and the reality behind the appearance "making itself perceptually manifest to someone."

The argument from illusion is an argument for the existence of sense-data. It is posed as a criticism of direct realism.

In philosophy and certain models of psychology, qualia are defined to be individual instances of subjective, conscious experience. The term qualia derives from the Latin neuter plural form (qualia) of the Latin adjective quālis meaning "of what sort" or "of what kind" in a specific instance like "what it is like to taste a specific apple, this particular apple now".

In the philosophy of perception, the theory of sense data was a popular view held in the early 20th century by philosophers such as Bertrand Russell, C. D. Broad, H. H. Price, A. J. Ayer, and G. E. Moore. Sense data are taken to be mind-dependent objects whose existence and properties are known directly to us in perception. These objects are unanalyzed experiences inside the mind, which appear to subsequent more advanced mental operations exactly as they are.

Louis Arnaud Reid was a British philosopher who held the foundation Chair in Philosophy of Education at the London University Institute of Education. He was a founding contributor to the British Journal of Aesthetics, and is best known for his writings on epistemology and aesthetics. He influenced figures as diverse as Susanne Langer, Lionel Trilling and Harold Osborne. Jacques Barzun said that Reid's A Study in Aesthetics was the book that most influenced him in his life.

In the philosophy of perception, critical realism is the theory that some of our sense-data can and do accurately represent external objects, properties, and events, while other of our sense-data do not accurately represent any external objects, properties, and events. Put simply, critical realism highlights a mind-dependent aspect of the world that reaches to understand the mind-independent world.

Scottish common sense realism

Scottish Common Sense Realism, also known as the Scottish School of Common Sense, is a realist school of philosophy that originated in the ideas of Scottish philosophers Thomas Reid, Adam Ferguson, James Beattie, and Dugald Stewart during the 18th-century Scottish Enlightenment. Reid emphasized man's innate ability to perceive common ideas and that this process is inherent in and interdependent with judgement. Common sense therefore, is the foundation of philosophical inquiry. Though best remembered for its opposition to the pervasive philosophy of David Hume, Scottish Common Sense philosophy is influential and evident in the works of Thomas Jefferson and late 18th-century American politics.


  1. Lehar, Steve. (2000). The Function of Conscious Experience: An Analogical Paradigm of Perception and Behavior, Consciousness and Cognition.
  2. Lehar, Steve. (2000). Naïve Realism in Contemporary Philosophy Archived 2012-08-11 at the Wayback Machine , The Function of Conscious Experience.
  3. Lehar, Steve. Representationalism Archived 2012-09-05 at the Wayback Machine
  4. Hearing (or audition) is the ability to perceive (create ideas of)sound by detecting vibrations. The sound waves of language cannot perceive directly. They are only heard, interpreted and understood because the physical waves were transformed into ideas (Mental representation of sound wages) by our brains.
  5. 1 2 Bernecker, S. (2008). The Metaphysics of Memory. Philosophical Studies Series. Springer. p. 62. ISBN   9781402082191. LCCN   2008921236. The distinction between direct and indirect realism about perception has an interesting history. There was a time when perception was understood to be of things themselves, not of our ideas of things. This is what we find in Aristotle and Aquinas, who maintain that the mind or understanding grasps the form of the material object without the matter. What we perceive directly, on this view, are material objects. This changed in the seventeenth century with Descartes and Locke. who can be read as saying that the primary objects of perception are not things external to the mind but sense-data. Sense-data are the messengers that stand between us and physical objects such as tables and chairs. While indirect realism was the standard view of early modern philosophers, nowadays direct realism is, once again, in fashion.
  6. 1 2 John W. Yolton, Realism and Appearances: An Essay in Ontology, Cambridge University Press, 2000, p. 136.
  7. A. B. Dickerson, Kant on Representation and Objectivity, Cambridge University Press, 2003, p. 85.
  8. 1 2 3 The Problem of Perception (Stanford Encyclopedia of Philosophy): "Paraphrasing David Hume (1739...; see also Locke 1690, Berkeley 1710, Russell 1912): nothing is ever directly present to the mind in perception except perceptual appearances."
  9. A. D. Smith, "On Primary and Secondary Qualities", Philosophical Review (1990), 221–54.
  10. Patrick Rysiew, New Essays on Thomas Reid, Routledge, 2017, p. 18.
  11. Michael Della Rocca (ed.), The Oxford Handbook of Spinoza, Oxford University Press, 2017, p. 288.
  12. Dennis Schulting, Jacco Verburgt (eds.), Kant's Idealism: New Interpretations of a Controversial Doctrine, Springer 2010, p. 203.
  13. Daniel Breazeale and Tom Rockmore (eds.), Fichte, German Idealism, and Early Romanticism, Rodopi, 2010, p. 20.
  14. Tom Rockmore, Before and After Hegel: A Historical Introduction to Hegel's Thought, Hackett Publishing, 2003, p. xviii: "Hegel follows Kant ... in limiting claims to know to the empirically real. In short, he adopts a view very similar to Kant's empirical realism."
  15. Samuel Lebens, Bertrand Russell and the Nature of Propositions: A History and Defence of the Multiple Relation Theory of Judgement, Routledge, 2017, p. 34.
  16. Robin D. Rollinger, Husserl's Position in the School of Brentano, Phaenomenologica 150, Dordrecht: Kluwer, 1999, p. 224 n. 1.
  17. Putnam, Hilary. Sep. 1994. "The Dewey Lectures 1994: Sense, Nonsense, and the Senses: An Inquiry into the Powers of the Human Mind." The Journal of Philosophy91(9):445–518.
  18. John McDowell, Mind and World. Harvard University Press, 1994, p. 26.
  19. Roger F. Gibson, "McDowell's Direct Realism and Platonic Naturalism", Philosophical Issues Vol. 7, Perception (1996), pp. 275–281.
  20. Galen Strawson, "Real Direct Realism", a lecture recorded 2014 at Marc Sanders Foundation, Vimeo.
  21. John R. Searle, Seeing Things as They Are: A Theory of Perception, Oxford University Press, 2015, p. 15.
  22. Revonsuo, Antti (2006) Inner Presence: Consciousness as a Biological Phenomenon, Cambridge MA: MIT Press.
  23. Rommetveit, Ragnar (1974) On Message Structure: A Framework for the Study of Language and Communication, London: John Wiley & Sons.
  24. Steiner, George (1998), After Babel: Aspects of Language and Translation, London & New York: Oxford University Press.
  25. Hardin, C. L. (1988) Color for Philosophers, Indianapolis IN: Hackett Pub. Co.
  26. Sellars, Roy Wood (1919), "The epistemology of evolutionary naturalism", Mind, 28:112, 407-26; se p. 414.
  27. Wright, Edmond (2005), Narrative, Perception, Language, and Faith, Basingstoke: Palgrave Macmillan, pp. 96-102.
  28. Ayer, A. J. (1957) The Problem of Knowledge, Harmondsworth: Penguin Books.
  29. Hobbes, Thomas (1839 [1655]), Elements of Philosophy, The First Section: Concerning Body, London: John Bohn, p. 389; Perkins, Moreland (1983), Sensing the World, Indianapolis IN: Hackett Pub. Co., pp. 286-7.
  30. Michael Tye (2006), 'The puzzle of true blue', Analysis, 66: 173-78; Matthen, Mohan (2009), 'Truly blue: an adverbial aspect of perceptual representation', Analysis, 69:1, 48-54.
  31. Wright, Edmond (2005), Narrative, Perception, Language, and Faith, Basingstoke: Palgrave Macmillan, pp. 103-120.
  32. Glasersfeld, Ernst von (1995), Radical Constructivism: A Way of Knowing and Learning, London: RoutledgeFalmer.
  33. 1 2 3 4 5 6 7 8 Epistemological Problems of Perception, Stanford Encyclopedia of Philosophy.
  34. 1 2 3 Naïve Realism, University of Reading.
  35. Gregory, Richard. (2003). Delusions. Perception.32, pp. 257-261.
  36. Green, Alex. (2003). The Empirical Description of Conscious Experience, The Science and Philosophy of Consciousness.