Perception in the context of Representationalism

Experience refers to conscious events in general, more specifically to perceptions, or to the practical knowledge and familiarity that is produced by these processes. Understood as a conscious event in the widest sense, experience involves a subject to which various items are presented. In this sense, seeing a yellow bird on a branch presents the subject with the objects "bird" and "branch", the relation between them and the property "yellow". Unreal items may be included as well, which happens when experiencing hallucinations or dreams. When understood in a more restricted sense, only sensory consciousness counts as experience. In this sense, experience is usually identified with perception and contrasted with other types of conscious events, like thinking or imagining. In a slightly different sense, experience refers not to the conscious events themselves but to the practical knowledge and familiarity they produce. Hence, it is important that direct perceptual contact with the external world is the source of knowledge. So an experienced hiker is someone who has actually lived through many hikes, not someone who merely read many books about hiking. This is associated both with recurrent past acquaintance and the abilities learned through them.

Many scholarly debates on the nature of experience focus on experience as a conscious event, either in the wide or the more restricted sense. One important topic in this field is the question of whether all experiences are intentional, i.e. are directed at objects different from themselves. Another debate focuses on the question of whether there are non-conceptual experiences and, if so, what role they could play in justifying beliefs. Some theorists claim that experiences are transparent, meaning that what an experience feels like only depends on the contents presented in this experience. Other theorists reject this claim by pointing out that what matters is not just what is presented but also how it is presented.

Epistemology is the branch of philosophy that examines the nature, origin, and limits of knowledge. Also called the theory of knowledge, it explores different types of knowledge, such as propositional knowledge about facts, practical knowledge in the form of skills, and knowledge by acquaintance as a familiarity through experience. Epistemologists study the concepts of belief, truth, and justification to understand the nature of knowledge. To discover how knowledge arises, they investigate sources of justification, such as perception, introspection, memory, reason, and testimony.

The school of skepticism questions the human ability to attain knowledge, while fallibilism says that knowledge is never certain. Empiricists hold that all knowledge comes from sense experience, whereas rationalists believe that some knowledge does not depend on it. Coherentists argue that a belief is justified if it coheres with other beliefs. Foundationalists, by contrast, maintain that the justification of basic beliefs does not depend on other beliefs. Internalism and externalism debate whether justification is determined solely by mental states or also by external circumstances.

Positivism is a philosophical school that holds that all genuine knowledge is either true by definition or positive – meaning a posteriori facts derived by reason and logic from sensory experience. Other ways of knowing, such as intuition, introspection, or religious faith, are rejected or considered meaningless.

Although the positivist approach has been a recurrent theme in the history of Western thought, modern positivism was first articulated in the early 19th century by Auguste Comte. His school of sociological positivism holds that society, like the physical world, operates according to scientific laws. After Comte, positivist schools arose in logic, psychology, economics, historiography, and other fields of thought. Generally, positivists attempted to introduce scientific methods to their respective fields. Since the turn of the 20th century, positivism, although still popular, has declined under criticism within the social sciences by antipositivists and critical theorists, among others, for its alleged scientism, reductionism, overgeneralizations, and methodological limitations. Positivism also exerted an unusual influence on Kardecism.

Knowledge is an awareness of facts, a familiarity with individuals and situations, or a practical skill. Knowledge of facts, also called propositional knowledge, is often characterized as true belief that is distinct from opinion or guesswork by virtue of justification. While there is wide agreement among philosophers that propositional knowledge is a form of true belief, many controversies focus on justification. This includes questions like how to understand justification, whether it is needed at all, and whether something else besides it is needed. These controversies intensified in the latter half of the 20th century due to a series of thought experiments called Gettier cases that provoked alternative definitions.

Knowledge can be produced in many ways. The main source of empirical knowledge is perception, which involves the usage of the senses to learn about the external world. Introspection allows people to learn about their internal mental states and processes. Other sources of knowledge include memory, rational intuition, inference, and testimony. According to foundationalism, some of these sources are basic in that they can justify beliefs, without depending on other mental states. Coherentists reject this claim and contend that a sufficient degree of coherence among all the mental states of the believer is necessary for knowledge. According to infinitism, an infinite chain of beliefs is needed.

The mind is that which thinks, feels, perceives, imagines, remembers, and wills. It covers the totality of mental phenomena, including both conscious processes, through which an individual is aware of external and internal circumstances, and unconscious processes, which can influence an individual without intention or awareness. The mind plays a central role in most aspects of human life, but its exact nature is disputed. Some characterizations focus on internal aspects, saying that the mind transforms information and is not directly accessible to outside observers. Others stress its relation to outward conduct, understanding mental phenomena as dispositions to engage in observable behavior.

The mind–body problem is the challenge of explaining the relation between matter and mind. Traditionally, mind and matter were often thought of as distinct substances that could exist independently from one another. The dominant philosophical position since the 20th century has been physicalism, which says that everything is material, meaning that minds are certain aspects or features of some material objects. The evolutionary history of the mind is tied to the development of nervous systems, which led to the formation of brains. As brains became more complex, the number and capacity of mental functions increased with particular brain areas dedicated to specific mental functions. Individual human minds also develop over time as they learn from experience and pass through psychological stages in the process of aging. Some people are affected by mental disorders, in which certain mental capacities do not function as they should.

Cognitions are mental activities that deal with knowledge. They encompass psychological processes that acquire, store, retrieve, transform, or otherwise use information. Cognitions are a pervasive part of mental life, helping individuals understand and interact with the world.

Cognitive processes are typically categorized by their function. Perception organizes sensory information about the world, interpreting physical stimuli, such as light and sound, to construct a coherent experience of objects and events. Attention prioritizes specific aspects while filtering out irrelevant information. Memory is the ability to retain, store, and retrieve information, including working memory and long-term memory. Thinking encompasses psychological activities in which concepts, ideas, and mental representations are considered and manipulated. It includes reasoning, concept formation, problem-solving, and decision-making. Many cognitive activities deal with language, including language acquisition, comprehension, and production. Metacognition involves knowledge about knowledge or mental processes that monitor and regulate other mental processes. Classifications also distinguish between conscious and unconscious processes and between controlled and automatic ones.

In linguistics, sound symbolism is the perceptual similarity between speech sounds and concept meanings. It is a form of linguistic iconicity. For example, the English word ding may sound similar to the actual sound of a bell.

Linguistic sound may be perceived as similar to not only sounds, but also to other sensory properties, such as size, vision, touch, or smell, or abstract domains, such as emotion or value judgment. Such correspondence between linguistic sound and meaning may significantly affect the form of spoken languages.

A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of stimuli. Although, in some cultures, five human senses were traditionally identified as such (namely sight, smell, touch, taste, and hearing), many more are now recognized. Senses used by non-human organisms are even greater in variety and number. During sensation, sense organs collect various stimuli (such as a sound or smell) for transduction, meaning transformation into a form that can be understood by the brain. Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior and thought.

In organisms, a sensory organ consists of a group of interrelated sensory cells that respond to a specific type of physical stimulus. Via cranial and spinal nerves (nerves of the central and peripheral nervous systems that relay sensory information to and from the brain and body), the different types of sensory receptor cells (such as mechanoreceptors, photoreceptors, chemoreceptors, thermoreceptors) in sensory organs transduct sensory information from these organs towards the central nervous system, finally arriving at the sensory cortices in the brain, where sensory signals are processed and interpreted (perceived).

Consciousness, at its simplest, is awareness of states or objects either internal to one's self or in one's external environment. However, its nature has led to millennia of explanations, analyses, and debate among philosophers, scientists, and theologians. Opinions differ about what exactly needs to be studied, or can even be considered consciousness. In some explanations, it is synonymous with mind, and at other times, an aspect of it.

In the past, consciousness meant one's "inner life": the world of introspection, private thought, imagination, and volition. Today, it often includes any kind of cognition, experience, feeling, or perception. It may be awareness, awareness of awareness, metacognition, or self-awareness, either continuously changing or not. There is also a medical definition that helps, for example, to discern "coma" from other states. The disparate range of research, notions, and speculations raises some curiosity about whether the right questions are being asked.

Information is an abstract concept that refers to something which has the power to inform. At the most fundamental level, it pertains to the interpretation (perhaps formally) of that which may be sensed, or their abstractions. Any natural process that is not completely random and any observable pattern in any medium can be said to convey some amount of information. Whereas digital signals and other data use discrete signs to convey information, other phenomena and artifacts such as analogue signals, poems, pictures, music or other sounds, and currents convey information in a more continuous form. Information is not knowledge itself, but the meaning that may be derived from a representation through interpretation.

The concept of information is relevant or connected to various concepts, including constraint, communication, control, data, form, education, knowledge, meaning, understanding, mental stimuli, pattern, perception, proposition, representation, and entropy.

Justification (also called epistemic justification) is a property of beliefs that fulfill certain norms about what a person should believe. Epistemologists often identify justification as a component of knowledge distinguishing it from mere true opinion. They study the reasons why someone holds a belief. Epistemologists are concerned with various features of belief, which include the ideas of warrant (a proper justification for holding a belief), knowledge, rationality, and probability, among others.

Debates surrounding epistemic justification often involve the structure of justification, including whether there are foundational justified beliefs or whether mere coherence is sufficient for a system of beliefs to qualify as justified. Another major subject of debate is the sources of justification, which might include perceptual experience (the evidence of the senses), reason, and authoritative testimony, among others.

A mental state, or a mental property, is a state of mind of a person. Mental states comprise a diverse class, including perception, pain/pleasure experience, belief, desire, intention, emotion, and memory. There is controversy concerning the exact definition of the term. According to epistemic approaches, the essential mark of mental states is that their subject has privileged epistemic access while others can only infer their existence from outward signs. Consciousness-based approaches hold that all mental states are either conscious themselves or stand in the right relation to conscious states. Intentionality-based approaches, on the other hand, see the power of minds to refer to objects and represent the world as the mark of the mental. According to functionalist approaches, mental states are defined in terms of their role in the causal network independent of their intrinsic properties. Some philosophers deny all the aforementioned approaches by holding that the term "mental" refers to a cluster of loosely related ideas without an underlying unifying feature shared by all. Various overlapping classifications of mental states have been proposed. Important distinctions group mental phenomena together according to whether they are sensory, propositional, intentional, conscious or occurrent. Sensory states involve sense impressions like visual perceptions or bodily pains. Propositional attitudes, like beliefs and desires, are relations a subject has to a proposition. The characteristic of intentional states is that they refer to or are about objects or states of affairs. Conscious states are part of the phenomenal experience while occurrent states are causally efficacious within the owner's mind, with or without consciousness. An influential classification of mental states is due to Franz Brentano, who argues that there are only three basic kinds: presentations, judgments, and phenomena of love and hate.

Mental states are usually contrasted with physical or material aspects. For (non-eliminative) physicalists, they are a kind of high-level property that can be understood in terms of fine-grained neural activity. Property dualists, on the other hand, claim that no such reductive explanation is possible. Eliminativists may reject the existence of mental properties, or at least of those corresponding to folk psychological categories such as thought and memory. Mental states play an important role in various fields, including philosophy of mind, epistemology and cognitive science. In psychology, the term is used not just to refer to the individual mental states listed above but also to a more global assessment of a person's mental health.

An unobservable (also called impalpable) is an entity whose existence, nature, properties, qualities or relations are not directly observable by humans. In philosophy of science, typical examples of "unobservables" are the force of gravity, causation and beliefs or desires. The distinction between observable and unobservable plays a central role in Immanuel Kant's distinction between noumena and phenomena as well as in John Locke's distinction between primary and secondary qualities. There is considerable disagreement about which objects should be classified as unobservable, for example, whether bacteria studied using microscopes or positrons studied using cloud chambers count as unobservable. Different notions of unobservability have been formulated corresponding to different types of obstacles to their observation.

The scientific method is an empirical method for acquiring knowledge that has been referred to while doing science since at least the 17th century. Historically, it was developed through the centuries from the ancient and medieval world. The scientific method involves careful observation coupled with rigorous skepticism, because cognitive assumptions can distort the interpretation of the observation. Scientific inquiry includes creating a testable hypothesis through inductive reasoning, testing it through experiments and statistical analysis, and adjusting or discarding the hypothesis based on the results.

Although procedures vary across fields, the underlying process is often similar. In more detail: the scientific method involves making conjectures (hypothetical explanations), predicting the logical consequences of hypothesis, then carrying out experiments or empirical observations based on those predictions. A hypothesis is a conjecture based on knowledge obtained while seeking answers to the question. Hypotheses can be very specific or broad but must be falsifiable, implying that it is possible to identify a possible outcome of an experiment or observation that conflicts with predictions deduced from the hypothesis; otherwise, the hypothesis cannot be meaningfully tested.

The distinction between subjectivity and objectivity is a basic idea of philosophy, particularly epistemology and metaphysics. Various understandings of this distinction have evolved through the work of philosophers over centuries. One basic distinction is:

• Something is subjective if it is dependent on minds (such as biases, perception, emotions, opinions, imaginary objects, or conscious experiences). If a claim is true exclusively when considering the claim from the viewpoint of a sentient being, it is subjectively true. For example, one person may consider the weather to be pleasantly warm, and another person may consider the same weather to be too hot; both views are subjective.
• Something is objective if it can be confirmed or assumed independently of any minds. If a claim is true even when considering it outside the viewpoint of a sentient being, then it may be labelled objectively true. For example, many people would regard "2 + 2 = 4" as an objective statement of mathematics.

Both ideas have been given various and ambiguous definitions by differing sources as the distinction is often a given but not the specific focal point of philosophical discourse. The two words are usually regarded as opposites, though complications regarding the two have been explored in philosophy: for example, the view of particular thinkers that objectivity is an illusion and does not exist at all, or that a spectrum joins subjectivity and objectivity with a gray area in-between, or that the problem of other minds is best viewed through the concept of intersubjectivity, developing since the 20th century.

Intrapersonal communication (also known as autocommunication or inner speech) is communication with oneself or self-to-self communication. Examples are thinking to oneself "I will do better next time" after having made a mistake or imagining a conversation with one's boss in preparation for leaving work early. It is often understood as an exchange of messages in which sender and receiver are the same person. Some theorists use a wider definition that goes beyond message-based accounts and focuses on the role of meaning and making sense of things. Intrapersonal communication can happen alone or in social situations. It may be prompted internally or occur as a response to changes in the environment.

Intrapersonal communication encompasses a great variety of phenomena. A central type happens purely internally as an exchange within one's mind. Some researchers see this as the only form. In a wider sense, however, there are also types of self-to-self communication that are mediated through external means, like when writing a diary or a shopping list for oneself. For verbal intrapersonal communication, messages are formulated using a language, in contrast to non-verbal forms sometimes used in imagination and memory. One contrast among inner verbal forms is between self-talk and inner dialogue. Self-talk involves only one voice talking to itself. For inner dialogue, several voices linked to different positions take turns in a form of imaginary interaction. Other phenomena related to intrapersonal communication include planning, problem-solving, perception, reasoning, self-persuasion, introspection, and dreaming.