TheInfoList

In their most common sense, the terms thought and thinking refer to conscious cognitive processes that can happen independently of sensory stimulation. Their most paradigmatic forms are judging, reasoning, concept formation, problem solving, and deliberation. But other mental processes, like considering an
idea In common usage and in philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, existence, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philoso ...

, memory, or imagination, are also often included. These processes can happen internally independent of the
sensory organs Sense relates to any of the systems and corresponding organs involved in sensation, i.e. the physical process of responding to stimuli and providing data Data are units of information Information can be thought of as the resolution of ...
, unlike perception. But when understood in the widest sense, any mental event may be understood as a form of thinking, including perception and unconscious mental processes. In a slightly different sense, the term ''thought'' refers not to the mental processes themselves but to mental states or systems of ideas brought about by these processes. Various theories of thinking have been proposed. They aim to capture the characteristic features of thinking. ''
Platonists Platonism is the philosophy of Plato and school of thought, philosophical systems closely derived from it, though contemporary platonists do not necessarily accept all of the doctrines of Plato. Platonism had a profound effect on Western thought. ...
'' hold that thinking consists in discerning and inspecting Platonic forms and their interrelations. It involves the ability to discriminate between the pure Platonic forms themselves and the mere imitations found in the world. According to ''
Aristotelianism Aristotelianism ( ) is a philosophical tradition inspired by the work of Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher A philosopher is someone who practices philo ...
'', to think about something is to instantiate in one's mind the universal
essence Essence ( la, essentia) is a polysemic Polysemy ( or ; from grc-gre, πολύ-, , "many" and , , "sign") is the capacity for a word or phrase to have multiple meanings, usually related by contiguity of meaning within a semantic field. Polysem ...
of the object of thought. These universals are abstracted from sense experience and are not understood as existing in a changeless
intelligibleIntelligibility may refer to: *Mutual intelligibility, in linguistics *Intelligibility (communication) *Intelligibility (philosophy) See also

*Immaterialism, in philosophy *Incorporeality {{disambiguation ...
world, in contrast to Platonism.
Conceptualism 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 ...
is closely related to Aristotelianism: it identifies thinking with mentally evoking concepts instead of instantiating essences. ''Inner speech theories'' claim that thinking is a form of inner speech in which words are silently expressed in the thinker's mind. According to some accounts, this happens in a regular language, like English or French. The ''
language of thought hypothesisThe language of thought hypothesis (LOTH), sometimes known as thought ordered mental expression (TOME), is a view in linguistics Linguistics is the science, scientific study of language. It encompasses the analysis of every aspect of language, ...
'', on the other hand, holds that this happens in the medium of a unique mental language called ''Mentalese''. Central to this idea is that linguistic representational systems are built up from atomic and compound representations and that this structure is also found in thought. '' Associationists'' understand thinking as the succession of ideas or images. They are particularly interested in the laws of association that govern how the
train of thought The train of thought or track of thought refers to the interconnection in the sequence of ideas expressed during a connected discourse Discourse is a generalization of the notion of a conversation to any form of communication. Discourse is a ma ...
unfolds. ''
Behaviorists Behaviorism is a systematic approach to understanding the behavior of humans and other animals. It assumes that behavior is either a reflex In biology Biology is the natural science that studies life and living organisms, including their ...
'', by contrast, identify thinking with behavioral dispositions to engage in public intelligent behavior as a reaction to particular external
stimuli A stimulus is something that causes a physiological response. It may refer to: *Stimulation Stimulation is the encouragement of development or the cause of activity generally. For example, "The press provides stimulation of political discourse." ...
. ''
Computationalism In philosophy of mind Philosophy of mind is a branch of philosophy that studies the ontology and nature of the mind and its relationship with the body. The mind–body problem is a paradigmatic issue in philosophy of mind, although a number o ...
'' is the most recent of these theories. It sees thinking in analogy to how computers work in terms of the storage, transmission, and processing of information. Various types of thinking are discussed in the academic literature. A ''judgment'' is a mental operation in which a
proposition In logic and linguistics, a proposition is the meaning of a declarative sentence (linguistics), sentence. In philosophy, "Meaning (philosophy), meaning" is understood to be a non-linguistic entity which is shared by all sentences with the same mea ...
is evoked and then either affirmed or denied. ''
Reasoning Reason is the capacity of consciously applying logic Logic is an interdisciplinary field which studies truth and reasoning Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Greek, Greek: ...

'', on the other hand, is the process of drawing conclusions from premises or evidence. Both judging and reasoning depend on the possession of the relevant concepts, which are acquired in the process of '' concept formation''. In the case of ''problem solving'', thinking aims at reaching a predefined goal by overcoming certain obstacles. ''
Deliberation Deliberation is a process of thoughtfully weighing options, usually prior to voting. Deliberation emphasizes the use of logic and reason as opposed to power-struggle, creativity, or dialogue. Group decision-making, Group decisions are generally mad ...
'' is an important form of practical thought that consists in formulating possible courses of action and assessing the reasons for and against them. This may lead to a decision by choosing the most favorable option. Both ''
episodic memory Episodic may refer to: * The nature of television series that are divided into short programs known as episodes * Episodic memory, types of memory that result from specific incidents in a lifetime * In Geology Geology (from the Ancient Greek ...
'' and ''
imagination Imagination is the ability to produce and simulate novel objects, sensations, and ideas in the mind The mind is the set of faculties responsible for mental Phenomenon, phenomena. Often the term is also identified with the phenomena themselves. ...

'' present objects and situations internally, in an attempt to accurately reproduce what was previously experienced or as a free rearrangement, respectively. '' Unconscious thought'' is thought that happens without being directly experienced. It is sometimes posited to explain how in cases where no conscious thought was employed. Thought is discussed in various academic disciplines. ''
Phenomenology Phenomenology may refer to: * Empirical research, when used to describe measurement methods in some sciences * An empirical relationship or phenomenological model * Phenomenology (architecture), based on the experience of building materials and the ...
'' is interested in the experience of thinking. An important question in this field concerns the experiential character of thinking and to what extent this character can be explained in terms of sensory experience. ''
Metaphysics Metaphysics is the branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, existence, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and ...

'' is, among other things, interested in the relation between
mind The mind is the set of faculties responsible for mental Phenomenon, phenomena. Often the term is also identified with the phenomena themselves. These faculties include thought, imagination, memory, Will (philosophy), will and sensation. They are ...

and
matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particl ...
. This concerns the question of how thinking can fit into the material world as described by the
natural sciences Natural science is a Branches of science, branch of science concerned with the description, understanding and prediction of Phenomenon, natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer r ...
. ''
Cognitive psychology Cognitive psychology is the scientific study of mental process Cognition () refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses many aspects of intellec ...
'' aims to understand thought as a form of information processing. ''
Developmental psychology Developmental psychology is the science, scientific study of how and why human beings change over the course of their life. Originally concerned with infants and children, the field has expanded to include adolescence, adult development, aging, ...
'', on the other hand, investigates the development of thought from birth to maturity and asks which factors this development depends on. ''
Psychoanalysis Psychoanalysis (from Greek language, Greek: + ) is a set of Theory, theories and Therapy, therapeutic techniques"What is psychoanalysis? Of course, one is supposed to answer that it is many things — a theory, a research method, a therapy, a bod ...

'' emphasizes the role of the
unconscious Unconscious may refer to: Physiology * Unconsciousness, the lack of consciousness or responsiveness to people and other environmental stimuli Psychology * Unconscious mind, the mind operating well outside the attention of the conscious mind as ...
in mental life. Other fields concerned with thought include
linguistics Linguistics is the science, scientific study of language. It encompasses the analysis of every aspect of language, as well as the methods for studying and modeling them. The traditional areas of linguistic analysis include phonetics, phonet ...

,
neuroscience Neuroscience is the science, scientific study of the nervous system. It is a Multidisciplinary approach, multidisciplinary science that combines physiology, anatomy, molecular biology, developmental biology, cytology, computer science and Mathem ...

,
artificial intelligence Artificial intelligence (AI) is intelligence Intelligence has been defined in many ways: the capacity for logic Logic (from Ancient Greek, Greek: grc, wikt:λογική, λογική, label=none, lit=possessed of reason, intellectual, ...

,
biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms, Developmenta ...

, and
sociology Sociology is a social science Social science is the Branches of science, branch of science devoted to the study of society, societies and the Social relation, relationships among individuals within those societies. The term was formerly ...
. Various concepts and theories are closely related to the topic of thought. The term ''"
law of thought The laws of thought are fundamental axiom An axiom, postulate or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Greek ''axíōma'' () 'th ...
"'' refers to three fundamental laws of logic: the law of contradiction, the law of excluded middle, and the principle of identity. ''
Counterfactual thinking Counterfactual thinking is a concept in psychology Psychology is the science of mind and behavior. Psychology includes the study of consciousness, conscious and Unconscious mind, unconscious phenomena, as well as feeling and thought. It is ...
'' involves mental representations of non-actual situations and events in which the thinker tries to assess what would be the case if things had been different. ''
Thought experiments A thought experiment is a hypothetical situation in which a hypothesis, theory, or principle is laid out for the purpose of thinking through its consequences. Johann Witt-Hansen established that Hans Christian Ørsted was the first to use the Germ ...
'' often employ counterfactual thinking in order to illustrate theories or to test their plausibility. ''
Critical thinking Critical thinking is the analysis of facts to form a judgment. The subject is complex; several different Critical thinking#Definitions, definitions exist, which generally include the rational, skepticism, skeptical, and unbiased analysis or evalu ...
'' is a form of thinking that is reasonable, reflective, and focused on determining what to believe or how to act. ''Positive thinking'' involves focusing one's attention on the positive aspects of one's situation and is intimately related to
optimism Optimism is an attitude reflecting a belief or hope that the outcome of some specific endeavor, or outcomes in general, will be positive, favorable, and desirable. A common idiom An idiom is a phrase or expression that typically presents a fig ...

.

# Definition

The terms "thought" and "thinking" refer to a wide variety of psychological activities. In their most common sense, they are understood as conscious processes that can happen independently of sensory stimulation. This includes various different mental processes, like considering an idea or proposition or judging it to be true. In this sense, memory and imagination are forms of thought but perception is not. In a more restricted sense, only the most paradigmatic cases are considered thought. These involve conscious processes that are conceptual or linguistic and sufficiently abstract, like judging, inferring, problem solving, and deliberating. Sometimes the terms "thought" and "thinking" are understood in a very wide sense as referring to any form of mental process, conscious or unconscious. In this sense, it may be used synonymously with the term "mind". This usage is encountered, for example, in the , where minds are understood as thinking things, and in the
cognitive science Cognitive science is the interdisciplinary Interdisciplinarity or interdisciplinary studies involves the combination of two or more academic disciplines into one activity (e.g., a research project). It draws knowledge from several other fie ...
s. But this sense may include the restriction that such processes have to lead to intelligent behavior to be considered thought. A contrast sometimes found in the academic literature is that between thinking and
feeling Feeling was originally used to describe the physical sensation of touch through either experience or perception. The word is also used to describe other experiences, such as "Emotion, a feeling of warmth" and of sentience in general. In psychology ...

. In this context, thinking is associated with a sober, dispassionate, and
rational Rationality is the quality or state of being rational – that is, being based on or agreeable to reason Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Greek, Greek: grc, wikt:λογι ...
approach to its topic while feeling involves a direct
emotion Emotions are mental state, psychological states brought on by neurophysiology, neurophysiological changes, variously associated with thoughts, feelings, behavioural responses, and a degree of pleasure or suffering, displeasure. There is currentl ...

al engagement. The terms "thought" and "thinking" can also be used to refer not to the mental processes themselves but to mental states or systems of ideas brought about by these processes. In this sense, they are often synonymous with the term "belief" and its cognates and may refer to the mental states which either belong to an individual or are common among a certain group of people. Discussions of thought in the academic literature often leave it implicit which sense of the term they have in mind. The word ''thought'' comes from
Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, which has eventu ...
''þoht'', or ''geþoht'', from the stem of ''þencan'' "to conceive of in the mind, consider".

# Theories of thinking

Various theories of thinking have been proposed. They aim to capture the characteristic features of thinking. The theories listed here are not exclusive: it may be possible to combine some without leading to a contradiction.

## Platonism

According to
Platonism Platonism is the philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, existence, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of ...
, thinking is a spiritual activity in which
Platonic form Platonic realism is the philosophy, philosophical position that universals (metaphysics), universals or abstract objects exist objectively and outside of human minds. It is named after the Greek philosophy, Greek philosopher Plato who applied Phi ...
s and their interrelations are discerned and inspected. This activity is understood as a form of silent inner speech in which the soul talks to itself. Platonic forms are seen as universals that exist in a changeless realm different from the sensible world. Examples include the forms of goodness, beauty, unity, and sameness. On this view, the difficulty of thinking consists in being able to grasp the Platonic forms and to distinguish them as the original from the mere imitations found in the sensory world. This means, for example, distinguishing beauty itself from derivative images of beauty. One problem for this view is to explain how humans can learn and think about Platonic forms belonging to a different realm. Plato himself tries to solve this problem through his theory of recollection, according to which the soul already was in contact with the Platonic forms before and is therefore able to remember what they are like. But this explanation depends on various assumptions usually not accepted in contemporary thought.

## Aristotelianism and conceptualism

Aristotelians Aristotelianism ( ) is a philosophical tradition inspired by the work of Aristotle, usually characterized by Prior Analytics, deductive logic and an posterior analytics, analytic inductive method in the study of nature and Natural_law#Aristotle, na ...
hold that the mind is able to think about something by instantiating the essence of the object of thought. So while thinking about trees, the mind instantiates tree-ness. This instantiation does not happen in matter, as is the case for actual trees, but in mind, though the universal essence instantiated in both cases is the same. In contrast to Platonism, these universals are not understood as Platonic forms existing in a changeless intelligible world. Instead, they only exist to the extent that they are instantiated. The mind learns to discriminate universals through abstraction from experience. This explanation avoids various of the objections raised against Platonism. Conceptualism is closely related to Aristotelianism. It holds that thinking consists in mentally evoking concepts. Some of these concepts may be innate, but most have to be learned through abstraction from sense experience before they can be used in thought. It has been argued against these views that they have problems in accounting for the logical form of thought. For example, to think that it will either rain or snow, it is not sufficient to instantiate the essences of rain and snow or to evoke the corresponding concepts. The reason for this is that the disjunctive relation between the rain and the snow is not captured this way. Another problem shared by these positions is the difficulty of giving a satisfying account of how essences or concepts are learned by the mind through abstraction.

## Inner speech theory

Inner speech theories claim that thinking is a form of inner speech. This view is sometimes termed ''psychological nominalism''. It states that thinking involves silently evoking words and connecting them to form mental sentences. The knowledge a person has of their thoughts can be explained as a form of overhearing one's own silent monologue. Three central aspects are often ascribed to inner speech: it is in an important sense similar to hearing sounds, it involves the use of language and it constitutes a motor plan that could be used for actual speech. This connection to language is supported by the fact that thinking is often accompanied by muscle activity in the speech organs. This activity may facilitate thinking in certain cases but is not necessary for it in general. According to some accounts, thinking happens not in a regular language, like English or French, but has its own type of language with the corresponding symbols and syntax. This theory is known as the
language of thought hypothesisThe language of thought hypothesis (LOTH), sometimes known as thought ordered mental expression (TOME), is a view in linguistics Linguistics is the science, scientific study of language. It encompasses the analysis of every aspect of language, ...
. Inner speech theory has a strong initial plausibility since introspection suggests that indeed many thoughts are accompanied by inner speech. But its opponents usually contend that this is not true for all types of thinking. It has been argued, for example, that forms of daydreaming constitute non-linguistic thought. This issue is relevant to the question of whether animals have the capacity to think. If thinking is necessarily tied to language then this would suggest that there is an important gap between humans and animals since only humans have a sufficiently complex language. But the existence of non-linguistic thoughts suggests that this gap may not be that big and that some animals do indeed think.

### Language of thought hypothesis

There are various theories about the relation between language and thought. One prominent version in contemporary philosophy is called the
language of thought hypothesisThe language of thought hypothesis (LOTH), sometimes known as thought ordered mental expression (TOME), is a view in linguistics Linguistics is the science, scientific study of language. It encompasses the analysis of every aspect of language, ...
. It states that thinking happens in the medium of a mental language. This language, often referred to as ''Mentalese'', is similar to regular languages in various respects: it is composed of words that are connected to each other in syntactic ways to form sentences. This claim does not merely rest on an intuitive analogy between language and thought. Instead, it provides a clear definition of the features a representational system has to embody in order to have a linguistic structure. On the level of syntax, the representational system has to possess two types of representations: atomic and compound representations. Atomic representations are basic whereas compound representations are constituted either by other compound representations or by atomic representations. On the level of semantics, the semantic content or the meaning of the compound representations should depend on the semantic contents of its constituents. A representational system is linguistically structured if it fulfills these two requirements. The language of thought hypothesis states that the same is true for thinking in general. This would mean that thought is composed of certain atomic representational constituents that can be combined as described above. Apart from this abstract characterization, no further concrete claims are made about how human thought is implemented by the brain or which other similarities to natural language it has. The language of thought hypothesis was first introduced by
Jerry Fodor Jerry Alan Fodor (; April 22, 1935 – November 29, 2017) was an American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the United States The United States of Ameri ...

. He argues in favor of this claim by holding that it constitutes the best explanation of the characteristic features of thinking. One of these features is ''productivity'': a system of representations is ''productive'' if it can generate an infinite number of unique representations based on a low number of atomic representations. This applies to thought since human beings are capable of entertaining an infinite number of distinct thoughts even though their mental capacities are quite limited. Other characteristic features of thinking include ''systematicity'' and ''inferential coherence''. Fodor argues that the language of thought hypothesis is true because it explains how thought can have these features and because there is no good alternative explanation. Some arguments against the language of thought hypothesis are based on neural networks, which are able to produce intelligent behavior without depending on representational systems. Other objections focus on the idea that some mental representations happen non-linguistically, for example, in the form of maps or images. Computationalists have been especially interested in the language of thought hypothesis since it provides ways to close the gap between thought in the human brain and computational processes implemented by computers. The reason for this is that processes over representations that respect syntax and semantics, like
inference Inferences are steps in reasoning, moving from premises to logical consequences; etymologically, the word ''wikt:infer, infer'' means to "carry forward". Inference is theoretically traditionally divided into deductive reasoning, deduction and i ...

s according to the
modus ponens In propositional logic Propositional calculus is a branch of logic Logic (from Ancient Greek, Greek: grc, wikt:λογική, λογική, label=none, lit=possessed of reason, intellectual, dialectical, argumentative, translit=logikḗ ...

, can be implemented by physical systems using causal relations. The same linguistic systems may be implemented through different material systems, like brains or computers. In this way, computers can ''think''.

## Associationism

An important view in the empiricist tradition has been
associationism Associationism is the idea that mental processes operate by the association of one mental state with its successor states. It holds that all mental processes are made up of discrete psychological elements and their combinations, which are believed ...
, the view that thinking consists in the succession of ideas or images. This succession is seen as being governed by laws of association, which determine how the train of thought unfolds. These laws are different from logical relations between the contents of thoughts, which are found in the case of drawing inferences by moving from the thought of the premises to the thought of the conclusion. Various laws of association have been suggested. According to the laws of similarity and contrast, ideas tend to evoke other ideas that are either very similar to them or their opposite. The law of contiguity, on the other hand, states that if two ideas were frequently experienced together, then the experience of one tends to cause the experience of the other. In this sense, the history of an organism’s experience determines which thoughts the organism has and how these thoughts unfold. But such an association does not guarantee that the connection is meaningful or rational. For example, because of the association between the terms "cold" and "Idaho", the thought "this coffee shop is cold" might lead to the thought "Russia should annex Idaho". On form of associationism is imagism. It states that thinking involves entertaining a sequence of images where earlier images conjure up later images based on the laws of association. One problem with this view is that we can think about things that we cannot imagine. This is especially relevant when the thought involves very complex objects or infinities, which is common, for example, in mathematical thought. One criticism directed at associationism in general is that its claim is too far-reaching. There is wide agreement that associative processes as studied by associationists play some role in how thought unfolds. But the claim that this mechanism is sufficient to understand all thought or all mental processes is usually not accepted.

## Behaviorism

According to
behaviorism Behaviorism is a systematic approach to understanding the behavior of humans and other animals. It assumes that behavior is either a reflex evoked by the pairing of certain antecedent (behavioral psychology), antecedent stimuli in the environmen ...
, thinking consists in behavioral dispositions to engage in certain publicly observable behavior as a reaction to particular external stimuli. On this view, having a particular thought is the same as having a disposition to behave in a certain way. This view is often motivated by empirical considerations: it is very difficult to study thinking as a private mental process but it is much easier to study how organisms react to a certain situation with a given behavior. In this sense, the capacity to solve problems not through existing habits but through creative new approaches is particularly relevant. The term "behaviorism" is also sometimes used in a slightly different sense when applied to thinking to refer to a specific form of inner speech theory. This view focuses on the idea that the relevant inner speech is a derivative form of regular outward speech. This sense overlaps with how behaviorism is understood more commonly in philosophy of mind since these inner speech acts are not observed by the researcher but merely inferred from the subject's intelligent behavior. This remains true to the general behaviorist principle that behavioral evidence is required for any psychological hypothesis. One problem for behaviorism is that the same entity often behaves differently despite being in the same situation as before. This problem consists in the fact that individual thoughts or mental states usually do not correspond to one particular behavior. So thinking that the pie is tasty does not automatically lead to eating the pie, since various other mental states may still inhibit this behavior, for example, the belief that it would be impolite to do so or that the pie is poisoned.

## Computationalism

Computationalist theories of thinking, often found in the cognitive sciences, understand thinking as a form of information processing. These views developed with the rise of computers in the second part of the 20th century, when various theorists saw thinking in analogy to computer operations. On such views, the information may be encoded differently in the brain, but in principle, the same operations take place there as well, corresponding to the storage, transmission, and processing of information. But while this analogy has some intuitive attraction, theorists have struggled to give a more explicit explanation of what computation is. A further problem consists in explaining the sense in which thinking is a form of computing. The traditionally dominant view defines computation in terms of
Turing machine A Turing machine is a mathematical model of computation In computer science, and more specifically in computability theory (computer science), computability theory and computational complexity theory, a model of computation is a model which des ...

s, though contemporary accounts often focus on
neural network Artificial neural networks (ANNs), usually simply called neural networks (NNs), are computing systems vaguely inspired by the biological neural networks that constitute animal brain A brain is an organ (anatomy), organ that serves as the ...

s for their analogies. A Turing machine is capable of executing any algorithm based on a few very basic principles, such as reading a symbol from a cell, writing a symbol to a cell, and executing instructions based on the symbols read. This way it is possible to perform deductive reasoning following the
inference rule In the philosophy of logic, a rule of inference, inference rule or transformation rule is a logical form consisting of a function which takes premises, analyzes their Syntax (logic), syntax, and returns a conclusion (or multiple-conclusion logic, ...
s of
formal logic Logic is an interdisciplinary field which studies truth Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to r ...
as well as simulating many other functions of the mind, such as language processing, decision making, and motor control. But computationalism does not only claim that thinking is in some sense similar to computation. Instead, it is claimed that thinking just is a form of computation or that the mind is a Turing machine. Computationalist theories of thought are sometimes divided into functionalist and representationalist approaches. Functionalist approaches define mental states through their causal roles but allow both external and internal events in their causal network. Thought may be seen as a form of program that can be executed in the same way by many different systems, including humans, animals, and even robots. According to one such view, whether something is a thought only depends on its role "in producing further internal states and verbal outputs". Representationalism, on the other hand, focuses on the representational features of mental states and defines thoughts as sequences of intentional mental states. In this sense, computationalism is often combined with the language of thought hypothesis by interpreting these sequences as symbols whose order is governed by syntactic rules. Various arguments have been raised against computationalism. In one sense, it seems trivial since almost any physical system can be described as executing computations and therefore as thinking. For example, it has been argued that the molecular movements in a regular wall can be understood as computing an algorithm since they are "isomorphic to the formal structure of the program" in question under the right interpretation. This would lead to the implausible conclusion that the wall is thinking. Another objection focuses on the idea that computationalism captures only some aspects of thought but is unable to account for other crucial aspects of human cognition.

# Types of thinking

A great variety of types of thinking are discussed in the academic literature. A common approach divides them into those forms that aim at the creation of theoretical knowledge and those that aim at producing actions or correct decisions. But there is no universally accepted taxonomy summarizing all these types. In some cases, the same particular thought may belong to different categories at the same time. It may also depend on one's definition of thought whether some of the types listed here actually qualify as ''thought''.

## Entertaining, judging, and reasoning

Thinking is often identified with the act of
judging Judgement (or US spelling judgment) is also known as ''adjudication'' which means the evaluation of evidence to make a decision. Judgement is also the ability to make considered decisions. The term has four distinct uses: * Informal – opi ...
. A judgment is a mental operation in which a proposition is evoked and then either affirmed or denied. It involves deciding what to believe and aims at determining whether the judged proposition is true or false. Various theories of judgment have been proposed. The traditionally dominant approach is the combination theory. It states that judgments consist in the combination of concepts. On this view, to judge that "all men are mortal" is to combine the concepts "man" and "mortal". The same concepts can be combined in different ways, corresponding to different forms of judgment, for example, as "some men are mortal" or "no man is mortal". Other theories of judgment focus more on the relation between the judged proposition and reality. According to
Franz Brentano Franz Clemens Honoratus Hermann Josef Brentano (; ; 16 January 1838 – 17 March 1917) was an influential German philosopher, psychologist, and Catholic priest whose work strongly influenced not only students Edmund Husserl, Sigmund Freud Si ...
, a judgment is either a belief or a disbelief in the existence of some entity. In this sense, there are only two fundamental forms of judgment: "A exists" and "A does not exist". When applied to the sentence "all men are mortal", the entity in question is "immortal men", of whom it is said that they do not exist. Important for Brentano is the distinction between the mere representation of the content of the judgment and the affirmation or the denial of the content. The mere representation of a proposition is often referred to as "entertaining a proposition". This is the case, for example, when one considers a proposition but has not yet made up one's mind about whether it is true or false. The term "thinking" can refer both to judging and to mere entertaining. This difference is often explicit in the way the thought is expressed: "thinking that" usually involves a judgment whereas "thinking about" refers to the neutral representation of a proposition without an accompanying belief. In this case, the proposition is merely ''entertained'' but not yet ''judged''. Some forms of thinking may involve the representation of objects without any propositions, as when someone is thinking about their grandmother. Reasoning is one of the most paradigmatic forms of thinking. It is the process of drawing conclusions from premises or evidence. Types of reasoning can be divided into deductive and non-deductive reasoning.
Deductive reasoning Deductive reasoning, also deductive logic, is the process of reasoning Reason is the capacity of consciously applying logic Logic is an interdisciplinary field which studies truth and reasoning Reason is the capacity of consciously making ...
is governed by certain
rules of inference In the philosophy of logic Following the developments in formal logic with symbolic logic in the late nineteenth century and mathematical logic in the twentieth, topics traditionally treated by logic not being part of formal logic have tended to b ...
, which guarantee the truth of the conclusion if the premises are true. For example, given the premises "all men are mortal" and "Socrates is a man", it follows deductively that "Socrates is mortal". Non-deductive reasoning, also referred to as
defeasible reasoning In philosophical logicPhilosophical logic refers to those areas of philosophy in which recognized methods of logic have Classical logic, traditionally been used to solve or advance the discussion of philosophical problems. Among these, Sybil Wolfra ...
or non-monotonic reasoning, is still rationally compelling but the truth of the conclusion is not ensured by the truth of the premises.
Induction Induction may refer to: Philosophy * Inductive reasoning, in logic, inferences from particular cases to the general case Biology and chemistry * Labor induction (birth/pregnancy) * Induction chemotherapy, in medicine * Induction period, the t ...
is one form of non-deductive reasoning, for example, when one concludes that "the sun will rise tomorrow" based on one's experiences of all the previous days. Other forms of non-deductive reasoning include the
inference to the best explanation Abductive reasoning (also called abduction,For example: abductive inference, or retroduction) is a form of logical inference Inferences are steps in reasoning, moving from premises to logical consequences; etymologically, the word ''wikt:infe ...
and analogical reasoning.
Fallacies A fallacy is the use of invalid or otherwise faulty reason Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Greek, Greek: grc, wikt:λογική, λογική, label=none, lit=possessed of ...
are faulty forms of thinking that go against the norms of correct reasoning. Formal fallacies concern faulty inferences found in deductive reasoning.
Denying the antecedent Denying the antecedent, sometimes also called inverse error or fallacy of the inverse, is a formal fallacy In philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, ex ...
is one type of formal fallacy, for example, "If Othello is a bachelor, then he is male. Othello is not a bachelor. Therefore, Othello is not male".
Informal fallacies Informal fallacies are a type of incorrect argument In logic Logic is an interdisciplinary field which studies truth and reasoning Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Gree ...
, on the other hand, apply to all types of reasoning. The source of their flaw is to be found in the ''content'' or the ''context'' of the argument. This is often caused by ambiguous or vague expressions in
natural language In neuropsychology, linguistics, and the philosophy of language, a natural language or ordinary language is any language that has linguistic evolution, evolved naturally in humans through use and repetition without conscious planning or premedit ...
, as in "Feathers are light. What is light cannot be dark. Therefore, feathers cannot be dark". An important aspect of fallacies is that they seem to be rationally compelling on the first look and thereby seduce people into accepting and committing them. Whether an act of reasoning constitutes a fallacy does not depend on whether the premises are true or false but on their relation to the conclusion and, in some cases, on the context.

## Concept formation

Concept Concepts are defined as abstract ideas A mental representation (or cognitive representation), in philosophy of mind Philosophy of mind is a branch of philosophy that studies the ontology and nature of the mind and its relationship with the bod ...

s are general notions that constitute the fundamental building blocks of thought. They are rules that govern how objects are sorted into different classes. A person can only think about a proposition if they possess the concepts involved in this proposition. For example, the proposition "
wombat Wombats are short-legged, muscular quadrupedal marsupials that are native to Australia. They are about in length with small, stubby tails and weigh between . All three of the extant species are members of the family (biology), family Vombatid ...

s are animals" involves the concepts "wombat" and "animal". Someone who does not possess the concept "wombat" may still be able to read the sentence but cannot entertain the corresponding proposition. Concept formation is a form of thinking in which new concepts are acquired. It involves becoming familiar with the characteristic features shared by all instances of the corresponding type of entity and developing the ability to identify positive and negative cases. This process usually corresponds to learning the meaning of the word associated with the type in question. There are various theories concerning how concepts and concept possession are to be understood. According to one popular view, concepts are to be understood in terms of
abilities Ability may refer to: * Aptitude, a component of a competency to do a certain kind of work at a certain level * Intelligence, logic, abstract thought, understanding, self-awareness, communication, learning, having emotional knowledge, retaining, pl ...
. On this view, two central aspects characterize concept possession: the ability to discriminate between positive and negative cases and the ability to draw inferences from this concept to related concepts. Concept formation corresponds to acquiring these abilities. It has been suggested that animals are also able to learn concepts to some extend. This is due to their ability to discriminate between different types of situations and to adjust their behavior accordingly.

## Problem solving

In the case of
problem solving Problem solving consists of using generic or ad hoc Ad hoc is a List of Latin phrases, Latin phrase meaning literally 'to this'. In English, it generally signifies a solution designed for a specific problem or task, non-Generalization, gene ...

, thinking aims at reaching a predefined goal by overcoming certain obstacles. This process often involves two different forms of thinking. On the one hand, ''divergent thinking'' aims at coming up with as many alternative solutions as possible. On the other hand, ''convergent thinking'' tries to narrow down the range of alternatives to the most promising candidates. Some researchers identify various steps in the process of problem solving. These steps include recognizing the problem, trying to understand its nature, identifying general criteria the solution should meet, deciding how these criteria should be prioritized, monitoring the progress, and evaluating the results. An important distinction concerns the type of problem that is faced. For ''well-structured problems'', it is easy to determine which steps need to be taken to solve them, but executing these steps may still be difficult. For ill-structured problems, on the other hand, it is not clear what steps need to be taken, i.e. there is no clear formula that would lead to success if followed correctly. In this case, the solution may sometimes come in a flash of insight in which the problem is suddenly seen in a new light. Another way to categorize different forms of problem solving is by distinguishing between
algorithm of an algorithm (Euclid's algorithm) for calculating the greatest common divisor (g.c.d.) of two numbers ''a'' and ''b'' in locations named A and B. The algorithm proceeds by successive subtractions in two loops: IF the test B ≥ A yields "yes" ...

s and
heuristic A heuristic (; ), or heuristic technique, is any approach to problem solving Problem solving consists of using generic or ad hoc Ad hoc is a List of Latin phrases, Latin phrase meaning literally 'to this'. In English, it generally signifi ...
s. An algorithm is a formal procedure in which each step is clearly defined. It guarantees success if applied correctly. The
long multiplication A multiplication algorithm is an algorithm of an algorithm (Euclid's algorithm) for calculating the greatest common divisor (g.c.d.) of two numbers ''a'' and ''b'' in locations named A and B. The algorithm proceeds by successive subtractions in ...
usually taught in school is an example of an algorithm for solving the problem of multiplying big numbers. Heuristics, on the other hand, are informal procedures. They are rough rules-of-thumb that tend to bring the thinker closer to the solution but success is not guaranteed in every case even if followed correctly. Examples of heuristics are working forward and working backward. These approaches involve planning one step at a time, either starting and the beginning and moving forward or starting at the end and moving backward. So when planning a trip, one could plan the different stages of the trip from origin to destiny in the chronological order of how the trip will be realized, or in the reverse order. Obstacles to problem solving can arise from the thinker's failure to take certain possibilities into account by fixating on one specific course of action. There are important differences between how novices and experts solve problems. For example, experts tend to allocate more time for conceptualizing the problem and work with more complex representations whereas novices tend to devote more time to executing putative solutions.

## Deliberation and decision

Deliberation Deliberation is a process of thoughtfully weighing options, usually prior to voting. Deliberation emphasizes the use of logic and reason as opposed to power-struggle, creativity, or dialogue. Group decision-making, Group decisions are generally mad ...
is an important form of practical thinking. It aims at formulating possible courses of action and assessing their value by considering the reasons for and against them. This involves foresight to anticipate what might happen. Based on this foresight, different courses of action can be formulated in order to influence what will happen. Decisions are an important part of deliberation. They are about comparing alternative courses of action and choosing the most favorable one.
Decision theory Decision theory (or the theory of choice not to be confused with choice theory) is the study of an agent's choices. Decision theory can be broken into two branches: normative Normative generally means relating to an evaluative standard. Normativi ...
is a formal model of how ideal rational agents would make decisions. It is based on the idea that they should always choose the alternative with the highest expected value. Each alternative can lead to various possible outcomes, each of which has a different value. The expected value of an alternative consists in the sum of the values of each outcome associated with it multiplied by the probability that this outcome occurs. According to decision theory, a decision is rational if the agent chooses the alternative associated with the highest expected value, as assessed from the agent's own perspective. Various theorists emphasize the practical nature of thought, i.e. that thinking is usually guided by some kind of task it aims to solve. In this sense, thinking has been compared to trail-and-error seen in animal behavior when faced with a new problem. On this view, the important difference is that this process happens inwardly as a form of simulation. This process is often much more efficient since once the solution is found in thought, only the behavior corresponding to the found solution has to be outwardly carried out and not all the others.

## Episodic memory and imagination

When thinking is understood in a wide sense, it includes both
episodic memory Episodic may refer to: * The nature of television series that are divided into short programs known as episodes * Episodic memory, types of memory that result from specific incidents in a lifetime * In Geology Geology (from the Ancient Greek ...
and
imagination Imagination is the ability to produce and simulate novel objects, sensations, and ideas in the mind The mind is the set of faculties responsible for mental Phenomenon, phenomena. Often the term is also identified with the phenomena themselves. ...

. In episodic memory, events one experienced in the past are relived. It is a form of mental time travel in which the past experience is re-experienced. But this does not constitute an exact copy of the original experience since the episodic memory involves additional aspects and information not present in the original experience. This includes both a feeling of familiarity and chronological information about the past event in relation to the present. Memory aims at representing how things actually were in the past, in contrast to imagination, which presents objects without aiming to show how things actually are or were. Because of this missing link to actuality, more freedom is involved in most forms of imagination: its contents can be freely varied, changed, and recombined to create new arrangements never experienced before. Episodic memory and imagination have in common with other forms of thought that they can arise internally without any stimulation of the sensory organs. But they are still closer to sensation than more abstract forms of thought since they present sensory contents that could, at least in principle, also be perceived.

## Unconscious thought

Conscious , an English Paracelsian Paracelsianism (also Paracelsism; German: ') was an early modern History of medicine, medical movement based on the theories and therapies of Paracelsus. It developed in the second half of the 16th century, during the ...
thought is the paradigmatic form of thinking and is often the focus of the corresponding research. But it has been argued that some forms of thought also happen on the unconscious level. Unconscious thought is thought that happens in the background without being experienced. It is therefore not observed directly. Instead, its existence is usually inferred by other means. For example, when someone is faced with an important decision or a difficult problem, they may not be able to solve it straight away. But then, at a later time, the solution may suddenly flash before them even though no conscious steps of thinking were taken towards this solution in the meantime. In such cases, the cognitive labor needed to arrive at a solution is often explained in terms of unconscious thoughts. The central idea is that a cognitive transition happened and we need to posit unconscious thoughts to be able to explain how it happened. It has been argued that conscious and unconscious thoughts differ not just concerning their relation to experience but also concerning their capacities. According to unconscious thought theorists, for example, conscious thought excels at simple problems with few variables but is outperformed by unconscious thought when complex problems with many variables are involved. This is sometimes explained through the claim that the number of items one can consciously think about at the same time is rather limited whereas unconscious thought lacks such limitations. But other researchers have rejected the claim that unconscious thought is often superior to conscious thought. Other suggestions for the difference between the two forms of thinking include that conscious thought tends to follow formal logical laws while unconscious thought relies more on associative processing and that only conscious thinking is conceptually articulated and happens through the medium of language.

# In various disciplines

## Phenomenology

Phenomenology Phenomenology may refer to: * Empirical research, when used to describe measurement methods in some sciences * An empirical relationship or phenomenological model * Phenomenology (architecture), based on the experience of building materials and the ...
is the science of the structure and contents of
experience Experience refers to conscious , an English Paracelsian physician Consciousness, at its simplest, is " sentience or awareness of internal and external existence". Despite millennia of analyses, definitions, explanations and debates by philosoph ...

. The term "cognitive phenomenology" refers to the experiential character of thinking or what it feels like to think. Some theorists claim that there is no distinctive cognitive phenomenology. On such a view, the experience of thinking is just one form of sensory experience. According to one version, thinking just involves hearing a voice internally. According to another, there is no experience of thinking apart from the indirect effects thinking has on sensory experience. A weaker version of such an approach allows that thinking may have a distinct phenomenology but contends that thinking still depends on sensory experience because it cannot occur on its own. On this view, sensory contents constitute the foundation from which thinking may arise. An often-cited
thought experiment A thought experiment is a hypothetical situation in which a hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can t ...
in favor of the existence of a distinctive cognitive phenomenology involves two persons listening to a radio broadcast in French, one who understands French and the other who does not. The idea behind this example is that both listeners hear the same sounds and therefore have the same non-cognitive experience. In order to explain the difference, a distinctive cognitive phenomenology has to be posited: only the experience of the first person has this additional cognitive character since it is accompanied by a thought that corresponds to the meaning of what is said. Other arguments for the experience of thinking focus on the direct introspective access to thinking or on the thinker's knowledge of their own thoughts. Phenomenologists are also concerned with the characteristic features of the experience of thinking. Making a judgment is one of the prototypical forms of cognitive phenomenology. It involves epistemic agency, in which a proposition is entertained, evidence for and against it is considered, and, based on this reasoning, the proposition is either affirmed or rejected. It is sometimes argued that the experience of truth is central to thinking, i.e. that thinking aims at representing how the world is. It shares this feature with perception but differs from it in the way how it represents the world: without the use of sensory contents. One of the characteristic features often ascribed to thinking and judging is that they are predicative experiences, in contrast to the pre-predicative experience found in immediate perception. On such a view, various aspects of perceptual experience resemble judgments without being judgments in the strict sense. For example, the perceptual experience of the front of a house brings with it various expectations about aspects of the house not directly seen, like the size and shape of its other sides. This process is sometimes referred to as
apperceptionApperception (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the R ...
. These expectations resemble judgments and can be wrong. This would be the case when it turns out upon walking around the "house" that it is no house at all but only a front facade of a house with nothing behind it. In this case, the perceptual expectations are frustrated and the perceiver is surprised. There is disagreement as to whether these pre-predicative aspects of regular perception should be understood as a form of cognitive phenomenology involving thinking. This issue is also important for understanding the relation between thought and language. The reason for this is that the pre-predicative expectations do not depend on language, which is sometimes taken as an example for non-linguistic thought. Various theorists have argued that pre-predicative experience is more basic or fundamental since predicative experience is in some sense built on top of it and therefore depends on it. Another way how phenomenologists have tried to distinguish the experience of thinking from other types of experiences is in relation to ''empty intentions'' in contrast to ''intuitive intentions''. In this context, "intention" means that some kind of object is experienced. In ''intuitive intentions'', the object is presented through sensory contents. ''Empty intentions'', on the other hand, present their object in a more abstract manner without the help of sensory contents. So when perceiving a sunset, it is presented through sensory contents. The same sunset can also be presented non-intuitively when merely thinking about it without the help of sensory contents. In these cases, the same properties are ascribed to objects. The difference between these modes of presentation concerns not what properties are ascribed to the presented object but how the object is presented. Because of this commonality, it is possible for representations belonging to different modes to overlap or to diverge. For example, when searching one's glasses one may think to oneself that one left them on the kitchen table. This empty intention of the glasses lying on the kitchen table are then intuitively fulfilled when one sees them lying there upon arriving in the kitchen. This way, a perception can confirm or refute a thought depending on whether the empty intuitions are later fulfilled or not.

## Metaphysics

The
mind–body problem File:Dualism-vs-Monism.png, 350px, Different approaches toward resolving the mind–body problem The mind–body problem is a debate concerning the relationship between thought and consciousness in the human mind, and the brain as part of the phys ...
concerns the explanation of the relationship that exists between
mind The mind is the set of faculties responsible for mental Phenomenon, phenomena. Often the term is also identified with the phenomena themselves. These faculties include thought, imagination, memory, Will (philosophy), will and sensation. They are ...

s, or mental processes, and bodily states or processes. The main aim of philosophers working in this area is to determine the nature of the mind and mental states/processes, and how—or even if—minds are affected by and can affect the body. Human perceptual experiences depend on
stimuli A stimulus is something that causes a physiological response. It may refer to: *Stimulation Stimulation is the encouragement of development or the cause of activity generally. For example, "The press provides stimulation of political discourse." ...
which arrive at one's various
sensory organs Sense relates to any of the systems and corresponding organs involved in sensation, i.e. the physical process of responding to stimuli and providing data Data are units of information Information can be thought of as the resolution of ...
from the external world and these stimuli cause changes in one's mental state, ultimately causing one to feel a sensation, which may be pleasant or unpleasant. Someone's desire for a slice of pizza, for example, will tend to cause that person to move his or her body in a specific manner and in a specific direction to obtain what he or she wants. The question, then, is how it can be possible for conscious experiences to arise out of a lump of gray matter endowed with nothing but electrochemical properties. A related problem is to explain how someone's
propositional attitude A propositional attitude is a mental state held by an agent toward a proposition In logic and linguistics, a proposition is the meaning of a declarative sentence (linguistics), sentence. In philosophy, "Meaning (philosophy), meaning" is understood ...
s (e.g. beliefs and desires) can cause that individual's
neuron A neuron or nerve cell is an membrane potential#Cell excitability, electrically excitable cell (biology), cell that communicates with other cells via specialized connections called synapses. It is the main component of nervous tissue in all Anima ...

s to fire and his muscles to contract in exactly the correct manner. These comprise some of the puzzles that have confronted
epistemologist Epistemology (; ) is the branch of philosophy concerned with knowledge. Epistemologists study the nature, origin, and scope of knowledge, epistemic Justification (epistemology), justification, the Reason, rationality of belief, and various r ...
s and philosophers of mind from at least the time of
René Descartes René Descartes ( or ; ; Latinized Latinisation or Latinization can refer to: * Latinisation of names, the practice of rendering a non-Latin name in a Latin style * Latinisation in the Soviet Union, the campaign in the USSR during the 1920s a ...

. The above reflects a classical, functional description of how we work as cognitive, thinking systems. However the apparently irresolvable mind–body problem is said to be overcome, and bypassed, by the
embodied cognition Embodied cognition is the theory that many features of cognition Cognition () refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses many aspects of intellect ...
approach, with its roots in the work of
Heidegger Martin Heidegger (; ; 26 September 188926 May 1976) was a German philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=philosophos, meaning 'lover of wisdom ...

, ,
Vygotsky Lev Semyonovich Vygotsky (russian: Лев Семёнович Выго́тский, p=vɨˈɡotskʲɪj; be, Леў Сямёнавіч Выго́цкі, p=vɨˈɡotskʲɪj; – June 11, 1934) was a Soviet psychologist A psychologist is a pers ...
,
Merleau-Ponty Maurice Jean Jacques Merleau-Ponty (; 14 March 1908 – 3 May 1961) was a French phenomenological philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=phil ...
and the pragmatist
John Dewey John Dewey (; October 20, 1859 – June 1, 1952) was an American philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=philosophos, meaning 'lover of wisdom ...
. This approach states that the classical approach of separating the mind and analysing its processes is misguided: instead, we should see that the mind, actions of an embodied agent, and the environment it perceives and envisions, are all parts of a whole which determine each other. Therefore, functional analysis of the mind alone will always leave us with the mind–body problem which cannot be solved.

## Psychology

Psychologists have concentrated on thinking as an intellectual exertion aimed at finding an answer to a question or the solution of a practical problem. Cognitive psychology is a branch of
psychology Psychology is the science of mind and behavior. Psychology includes the study of consciousness, conscious and Unconscious mind, unconscious phenomena, as well as feeling and thought. It is an academic discipline of immense scope. Psychologis ...

that investigates internal mental processes such as problem solving, memory, and language; all of which are used in thinking. The school of thought arising from this approach is known as cognitivism, which is interested in how people mentally represent information processing. It had its foundations in the
Gestalt psychology Gestalt psychology, gestaltism or configurationism is a school of psychology that emerged in the early twentieth century in Austria and Germany as a theory of perception Perception (from the Latin ''perceptio'', meaning gathering or ...
of
Max Wertheimer Max Wertheimer (April 15, 1880 – October 12, 1943) was an Austro-Hungarian-born psychologist who was one of the three founders of Gestalt psychology, along with Kurt Koffka and Wolfgang Köhler. He is known for his book, ''Productive Thinking'', a ...
,
Wolfgang Köhler Wolfgang Köhler (21 January 1887 – 11 June 1967) was a German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of Germany, ...
, and
Kurt Koffka Kurt Koffka (March 12, 1886 – November 22, 1941) was a German psychologist and professor. He was born and educated in Berlin, Berlin, Germany; he died in Northampton, Massachusetts from coronary thrombosis. He was influenced by his maternal u ...

, and in the work of
Jean Piaget Jean Piaget (, , ; 9 August 1896 – 16 September 1980) was a Swiss Swiss may refer to: * the adjectival form of Switzerland *Swiss people Places *Swiss, Missouri *Swiss, North Carolina *Swiss, West Virginia *Swiss, Wisconsin Other uses *Swiss ...

, who provided a theory of stages/phases that describes children's cognitive development. Cognitive psychologists use psychophysical and experimental approaches to understand, diagnose, and solve problems, concerning themselves with the mental processes which mediate between stimulus and response. They study various aspects of thinking, including the
psychology of reasoning The psychology of reasoning is the study of how people reason, often broadly defined as the process of drawing conclusions to inform how people solve problems and make decisions. It overlaps with psychology, philosophy, linguistics, cognitive scie ...
, and how people make decisions and choices, solve problems, as well as engage in creative discovery and imaginative thought. Cognitive theory contends that solutions to problems either take the form of
algorithm of an algorithm (Euclid's algorithm) for calculating the greatest common divisor (g.c.d.) of two numbers ''a'' and ''b'' in locations named A and B. The algorithm proceeds by successive subtractions in two loops: IF the test B ≥ A yields "yes" ...

s: rules that are not necessarily understood but promise a solution, or of
heuristics A heuristic (; ), or heuristic technique, is any approach to problem solving Problem solving consists of using generic or ad hoc Ad hoc is a List of Latin phrases, Latin phrase meaning literally 'to this'. In English, it generally signifi ...

: rules that are understood but that do not always guarantee solutions.
Cognitive science Cognitive science is the interdisciplinary Interdisciplinarity or interdisciplinary studies involves the combination of two or more academic disciplines into one activity (e.g., a research project). It draws knowledge from several other fie ...
differs from cognitive psychology in that algorithms that are intended to simulate human behavior are implemented or implementable on a computer. In other instances, solutions may be found through insight, a sudden awareness of relationships. In
developmental psychology Developmental psychology is the science, scientific study of how and why human beings change over the course of their life. Originally concerned with infants and children, the field has expanded to include adolescence, adult development, aging, ...
,
Jean Piaget Jean Piaget (, , ; 9 August 1896 – 16 September 1980) was a Swiss Swiss may refer to: * the adjectival form of Switzerland *Swiss people Places *Swiss, Missouri *Swiss, North Carolina *Swiss, West Virginia *Swiss, Wisconsin Other uses *Swiss ...

was a pioneer in the study of the development of thought from birth to maturity. In his
theory of cognitive development Piaget's theory of cognitive development is a comprehensive theory about the nature and development of human intelligence. It was originated by the Swiss developmental psychologist Jean Piaget (1896–1980). The theory deals with the nature of k ...
, thought is based on actions on the environment. That is, Piaget suggests that the environment is understood through assimilations of objects in the available schemes of action and these accommodate to the objects to the extent that the available schemes fall short of the demands. As a result of this interplay between assimilation and accommodation, thought develops through a sequence of stages that differ qualitatively from each other in mode of representation and complexity of inference and understanding. That is, thought evolves from being based on perceptions and actions at the sensorimotor stage in the first two years of life to internal representations in early childhood. Subsequently, representations are gradually organized into logical structures which first operate on the concrete properties of the reality, in the stage of concrete operations, and then operate on abstract principles that organize concrete properties, in the stage of formal operations. In recent years, the Piagetian conception of thought was integrated with information processing conceptions. Thus, thought is considered as the result of mechanisms that are responsible for the representation and processing of information. In this conception, speed of processing,
cognitive control Executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior Behavior (American English) or behaviour (British English; ...
, and
working memory Working memory is a cognitive system with a limited capacity that can hold information temporarily. Working memory is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-ter ...
are the main functions underlying thought. In the
neo-Piagetian theories of cognitive development Neo-Piagetian theories of cognitive development criticize and build upon Jean Piaget's theory of cognitive development. Overview The neo-Piagetian theories aim to correct one or more of the following weaknesses in Piaget's theory: * Piaget's de ...
, the development of thought is considered to come from increasing speed of processing, enhanced
cognitive control Executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior Behavior (American English) or behaviour (British English; ...
, and increasing working memory.
Positive psychology Positive psychology is the scientific study of what makes life most worth living, focusing on both individual and societal well-being. It studies "positive subjective experience, positive individual traits, and positive institutions...it aims to ...
emphasizes the positive aspects of human psychology as equally important as the focus on mood disorders and other negative symptoms. In '''', Christopher Peterson (psychologist), Peterson and Martin Seligman, Seligman list a series of positive characteristics. One person is not expected to have every strength, nor are they meant to fully capsulate that characteristic entirely. The list encourages positive thought that builds on a person's strengths, rather than how to "fix" their "symptoms".

## Psychoanalysis

The "id", "ego" and "super-ego" are the three parts of the "psychic apparatus" defined in Sigmund Freud's ego psychology, structural model of the psyche; they are the three theoretical constructs in terms of whose activity and interaction mental life is described. According to this model, the uncoordinated instinctual trends are encompassed by the "id", the organized realistic part of the psyche is the "ego", and the critical, moralizing function is the "super-ego". For psychoanalysis, the unconscious does not include all that is not conscious, rather only what is actively repressed from conscious thought or what the person is averse to knowing consciously. In a sense this view places the self in relationship to their unconscious as an adversary, warring with itself to keep what is unconscious hidden. If a person feels pain, all he can think of is alleviating the pain. Any of his desires, to get rid of pain or enjoy something, command the mind what to do. For Freud, the unconscious was a repository for socially unacceptable ideas, wishes or desires, traumatic memories, and painful emotions put out of mind by the mechanism of psychological repression. However, the contents did not necessarily have to be solely negative. In the psychoanalytic view, the unconscious is a force that can only be recognized by its effects—it expresses itself in the symptom. The collective unconscious, sometimes known as collective subconscious, is a term of analytical psychology, Neologism, coined by Carl Jung. It is a part of the unconscious mind, shared by a society, a people, or all humanity, in an interconnected system that is the product of all common experiences and contains such concepts as science, religion, and morality. While Freud did not distinguish between "individual psychology" and "collective psychology", Jung distinguished the collective unconscious from the personal unconscious, personal unconscious mind, subconscious particular to each human being. The collective unconscious is also known as "a reservoir of the experiences of our species". In the "Definitions" chapter of Jung's wikt:seminal, seminal work ''Psychological Types'', under the definition of "collective" Jung references ''representations collectives'', a term coined by Lucien Lévy-Bruhl in his 1910 book ''How Natives Think''. Jung says this is what he describes as the collective unconscious. Freud, on the other hand, did not accept the idea of a collective unconscious.

# Related concepts and theories

## Laws of thought

Traditionally, the term "laws of thought" refers to three fundamental laws of logic: the law of contradiction, the law of excluded middle, and the principle of identity. These laws by themselves are not sufficient as axioms of logic but they can be seen as important precursors to the modern Axiomatic system, axiomatization of logic. The ''law of contradiction'' states that for any proposition, it is impossible that both it and its negation are true: $\lnot \left(p \land \lnot p\right)$. According to the ''law of excluded middle'', for any proposition, either it or its opposite is true: $p \lor \lnot p$. The principle of identity asserts that any object is identical to itself: $\forall x \left(x = x\right)$. There are different conceptions of how the laws of thought are to be understood. The interpretations most relevant to thinking are to understand them as prescriptive laws of how one should think or as formal laws of propositions that are true only because of their form and independent of their content or context. Metaphysics, Metaphysical interpretations, on the other hand, see them as expressing the nature of "being as such". While there is a very wide acceptance of these three laws among logicians, they are not universally accepted. Aristotle, for example, held that there are some cases in which the law of excluded middle is false. This concerns primarily uncertain future events. On his view, it is currently "not ... either true or false that there will be a naval battle tomorrow". Modern intuitionist logic also rejects the law of excluded middle. This rejection is based on the idea that mathematical truth depends on verification through a Mathematical proof, proof. The law fails for cases where no such proof is possible, which exist in every sufficiently strong formal system, according to Gödel's incompleteness theorems. Dialetheism, Dialetheists, on the other hand, reject the law of contradiction by holding that some propositions are both true and false. One motivation of this position is to avoid certain paradoxes in classical logic and set theory, like the liar's paradox and Russell's paradox. One of its problems is to find a formulation that circumvents the principle of explosion, i.e. that anything follows from a contradiction. Some formulations of the laws of thought include a fourth law: the principle of sufficient reason. It states that everything has a sufficient reason, ground, or cause. It is closely connected to the idea that everything is intelligible or can be explained in reference to its sufficient reason. According to this idea, there should always be a full explanation, at least in principle, to questions like why the sky is blue or why World War II happened. One problem for including this principle among the laws of thought is that it is a metaphysical principle, unlike the other three laws, which pertain primarily to logic.

## Counterfactual thinking

Counterfactual thinking Counterfactual thinking is a concept in psychology Psychology is the science of mind and behavior. Psychology includes the study of consciousness, conscious and Unconscious mind, unconscious phenomena, as well as feeling and thought. It is ...

## Thought experiments

Thought experiments involve thinking about imaginary situations, often with the aim of investigating the possible consequences of a change to the actual sequence of events. It is a controversial issue to what extend thought experiments should be understood as actual experiments. They are experiments in the sense that a certain situation is set up and one tries to learn from this situation by understanding what follows from it. They differ from regular experiments in that imagination is used to set up the situation and counterfactual reasoning is employed to evaluate what follows from it, instead of setting it up physically and observing the consequences through perception. Counterfactual thinking, therefore, plays a central role in thought experiments. The Chinese room argument is a famous thought experiment proposed by John Searle. It involves a person sitting inside a closed-off room, tasked with responding to messages written in Chinese. This person does not know Chinese but has a giant rule book that specifies exactly how to reply to any possible message, similar to how a computer would react to messages. The core idea of this thought experiment is that neither the person nor the computer understands Chinese. This way, Searle aims to show that computers lack a mind capable of deeper forms of understanding despite acting intelligently. Thought experiments are employed for various purposes, for example, for entertainment, education, or as arguments for or against theories. Most discussions focus on their use as arguments. This use is found in fields like philosophy, the natural sciences, and history. It is controversial since there is a lot of disagreement concerning the epistemic status of thought experiments, i.e. how reliable they are as evidence supporting or refuting a theory. Central to the rejection of this usage is the fact that they pretend to be a source of knowledge without the need to leave one's armchair in search of any new empirical data. Defenders of thought experiments usually contend that the intuitions underlying and guiding the thought experiments are, at least in some cases, reliable. But thought experiments can also fail if they are not properly supported by intuitions or if they go beyond what the intuitions support. In the latter sense, sometimes counter thought experiments are proposed that modify the original scenario in slight ways in order to show that initial intuitions cannot survive this change. Various taxonomies of thought experiments have been suggested. They can be distinguished, for example, by whether they are successful or not, by the discipline that uses them, by their role in a theory, or by whether they accept or modify the actual laws of physics.

## Critical thinking

Critical thinking Critical thinking is the analysis of facts to form a judgment. The subject is complex; several different Critical thinking#Definitions, definitions exist, which generally include the rational, skepticism, skeptical, and unbiased analysis or evalu ...
is a form of thinking that is reasonable, reflective, and focused on determining what to believe or how to act. It holds itself to various standards, like clarity and rationality. In this sense, it involves not just cognitive processes trying to solve the issue at hand but at the same time Meta-cognition, meta-cognitive processes ensuring that it lives up to its own standards. This includes assessing both that the reasoning itself is sound and that the evidence it rests on is reliable. This means that logic plays an important role in critical thinking. It concerns not just
formal logic Logic is an interdisciplinary field which studies truth Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to r ...
, but also informal logic, specifically to avoid various informal fallacies due to vague or ambiguous expressions in natural language. No generally accepted standard definition of "critical thinking" exists but there is significant overlap between the proposed definitions in their characterization of critical thinking as careful and goal-directed. According to some versions, only the thinker's own observations and experiments are accepted as evidence in critical thinking. Some restrict it to the formation of judgments but exclude action as its goal. A concrete everyday example of critical thinking, due to
John Dewey John Dewey (; October 20, 1859 – June 1, 1952) was an American philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=philosophos, meaning 'lover of wisdom ...
, involves observing foam bubbles moving in a direction that is contrary to one's initial expectations. The critical thinker tries to come up with various possible explanations of this behavior and then slightly modifies the original situation in order to determine which one is the right explanation. But not all forms of cognitively valuable processes involve critical thinking. Arriving at the correct solution to a problem by blindly following the steps of an algorithm does not qualify as critical thinking. The same is true if the solution is presented to the thinker in a sudden flash of insight and accepted straight away. Critical thinking plays an important role in education: fostering the student's ability to think critically is often seen as an important educational goal. In this sense, it is important to convey not just a set of true beliefs to the student but also the ability to draw one's own conclusions and to question pre-existing beliefs. The abilities and dispositions learned this way may profit not just the individual but also society at large. Critics of the emphasis on critical thinking in education have argued that there is no universal form of correct thinking. Instead, they contend that different subject matters rely on different standards and education should focus on imparting these subject-specific skills instead of trying to teach universal methods of thinking. Other objections are based on the idea that critical thinking and the attitude underlying it involve various unjustified biases, like egocentrism, distanced objectivity, indifference, and an overemphasis of the theoretical in contrast to the practical.

## Positive thinking

Positive thinking is an important topic in positive psychology. It involves focusing one's attention on the positive aspects of one's situation and thereby withdrawing one's attention from its negative sides. This is usually seen as a global outlook that applies especially to thinking but includes other mental processes, like feeling, as well. In this sense, it is closely related to
optimism Optimism is an attitude reflecting a belief or hope that the outcome of some specific endeavor, or outcomes in general, will be positive, favorable, and desirable. A common idiom An idiom is a phrase or expression that typically presents a fig ...

. It includes expecting positive things to happen in the future. This positive outlook makes it more likely for people to seek to attain new goals. It also increases the probability of continuing to strive towards pre-existing goals that seem difficult to reach instead of just giving up. The effects of positive thinking are not yet thoroughly researched, but some studies suggest that there is a correlation between positive thinking and well-being. For example, students and pregnant women with a positive outlook tend to be better at dealing with stressful situations. This is sometimes explained by pointing out that stress is not inherent in stressful situations but depends on the agent's interpretation of the situation. Reduced stress may therefore be found in positive thinkers because they tend to see such situations in a more positive light. But the effects also include the practical domain in that positive thinkers tend to employ healthier coping strategies when faced with difficult situations. This effects, for example, the time needed to fully recover from surgeries and the tendency to resume physical exercise afterward. But it has been argued that whether positive thinking actually leads to positive outcomes depends on various other factors. Without these factors, it may lead to negative results. For example, the tendency of optimists to keep striving in difficult situations can backfire if the course of events is outside the agent's control. Another danger associated with positive thinking is that it may remain only on the level of unrealistic fantasies and thereby fail to make a positive practical contribution to the agent's life. Defensive pessimism, Pessimism, on the other hand, may have positive effects since it can mitigate disappointments by anticipating failures. Positive thinking is a recurrent topic in the self-help literature. Here, often the claim is made that one can significantly improve one's life by trying to think positively, even if this means fostering beliefs that are contrary to evidence. Such claims and the effectiveness of the suggested methods are controversial and have been criticized due to their lack of scientific evidence. In the New Thought movement, positive thinking figures in the Law of attraction (New Thought), law of attraction, the pseudoscientific claim that positive thoughts can directly influence the external world by attracting positive outcomes.

* Animal cognition * Outline of thought – topic tree that identifies many types of thoughts, types of thinking, aspects of thought, related fields, and more * Outline of human intelligence – topic tree presenting the traits, capacities, models, and research fields of human intelligence, and more * Rethinking