bluuebunny/crossref_metadata_2025 huggingface dataset:
Belief
Authors: Braddon-Mitchell David , Jackson Frank
Published: September 2018

We believe that there is coffee over there; we believe the special theory of relativity; we believe the surgeon; some of us believe in God. But plausibly what is fundamental is believing that something is the case – believing a proposition, as it is usually put. To believe a theory is to believe the propositions that make up the theory, to believe a person is to believe some proposition advanced by them; and to believe in God is to believe the proposition that God exists. Thus belief is said to be a propositional attitude or intentional state: to believe is to take the attitude of belief to some proposition. It is about what its propositional object is about (God, the operation, or whatever). We can think of the propositional object of a belief as the way the belief represents things as being – its content, as it is often called.

We state what we believe with indicative sentences in ‘that’-clauses, as in ‘Mary believes that the Democrats will win the next election ’. But belief in the absence of language is possible. A dog may believe that there is food in the bowl in front of it. Accordingly philosophers have sought accounts of belief that allow a central role to sentences – it cannot be an accident that finding the right sentence is the way to capture what some person believes – while allowing that creatures without a language can have beliefs. One way of doing this is to construe beliefs as relations to inner sentences somehow inscribed in the brain. On this view, although dogs do not have a public language, to the extent that they have beliefs they have something sentence-like in their heads.

An alternative tradition focuses on the way belief when combined with desire leads to behaviour, and analyses belief in terms of behavioural dispositions or more recently as the internal state that is, in combination with other mental states, responsible for the appropriate behavioural dispositions.

An earlier tradition associated with the British empiricists views belief as a kind of pale imitation of perceptual experience. But recent work on belief largely takes for granted a sharp distinction between belief and the various mental images that may or may not accompany it.

A focus of recent discussions of belief has been the extent to which what a subject believes is a function of their surroundings. Everyone agrees that what subjects believe is causally influenced by their surroundings. The sun’s impact on my sense organs causes me to believe that it is sunny. But many argue that the role of subjects’ surroundings in determining what is believed outruns their causal effects.
Dreaming
Authors: Casati Roberto
Published: September 2018

We naturally think of dreams as experiences very like perceptions or imaginings, except that they occur during sleep. In prescientific thought the interpretation of dreams played a role in divining the future, and it plays a role, albeit a much more limited one, in modern psychology (although in Freudian psychoanalysis dreams have been considered to give access to some of the hidden operations of the mind). Dreaming is puzzling in many respects. We do not have ready-to-hand criteria for checking dream reports, not even our own; conscious or lucid dreams are the exception rather than the rule; and there is the puzzle of how we distinguish waking experience from a very lifelike dream. Furthermore, the nature of dreams is doubtful – some have even denied that to dream is to undergo an experience during sleep: dreams on this view are to be understood in terms of what happens when we ’recall’ them.
Intentionality
Authors: Crane Tim
Published: September 2018

Intentionality is the mind’s capacity to direct itself on things. Mental states like thoughts, beliefs, desires, hopes (and others) exhibit intentionality in the sense that they are always directed on, or at, something: if you hope, believe or desire, you must hope, believe or desire something. Hope, belief, desire and any other mental state which is directed at something, are known as intentional states. Intentionality in this sense has only a peripheral connection to the ordinary ideas of intention and intending. An intention to do something is an intentional state, since one cannot intend without intending something; but intentions are only one of many kinds of intentional mental states.

The terminology of intentionality derives from the scholastic philosophy of the Middle Ages, and was revived by Brentano in 1874. Brentano characterized intentionality in terms of the mind’s direction upon an object, and emphasized that the object need not exist. He also claimed that it is the intentionality of mental phenomena that distinguishes them from physical phenomena. These ideas of Brentano’s provide the background to twentieth-century discussions of intentionality, in both the phenomenological and analytic traditions. Among these discussions, we can distinguish two general projects. The first is to characterize the essential features of intentionality. For example, is intentionality a relation? If it is, what does it relate, if the object of an intentional state need not exist in order to be thought about? The second is to explain how intentionality can occur in the natural world. How can merely biological creatures exhibit intentionality? The aim of this second project is to explain intentionality in non-intentional terms.
Mental illness, concept of
Authors: Neander Karen
Published: September 2018

The mad were once thought to be wicked or possessed, whereas now they are generally thought to be sick, or mentally ill. Usually, this is regarded as a benign decision by a more enlightened age, but some see it as a double-edged sword – one that simultaneously relieved and robbed the mad of responsibility for their actions, eventually delivering more compassionate treatment, but also disguising value-laden judgments as objective science. The issue is made more difficult by the diversity of conditions classified as psychiatric disorders, and by the extent to which their causes are still ill understood. But the difficulty is also conceptual: what, after all, is physical illness? People usually agree that it involves abnormal body functioning, but how do we decide what is normal functioning? And even supposing that we know what we mean by a sick body, is there a parallel notion of a sick mind that is more than metaphor?
Other Minds
Authors: Hyslop Alec
Published: September 2018

It has traditionally been thought that the problem of other minds is epistemological: how is it that we know other people have thoughts, experiences and emotions? After all, we have no direct knowledge that this is so. We observe their behaviour and their bodies, not their thoughts, experiences and emotions. The task is seen as being to uncover the justification for our belief in other minds. It has also been thought that there is a conceptual problem: how can we manage to have any conception of mental states other than our own? It is noteworthy that there is as yet no standard view on either of these problems. One answer to the traditional (epistemological) problem has been the analogical inference to other minds, appealing to the many similarities existing between ourselves and others. This answer, though it is no longer in general favour among philosophers, still has its defenders. Probably the favoured solution is to view other minds as logically on a par with the unobservable, theoretical entities of science. That other people have experiences, like us, is seen as the best explanation of their behaviour.
Perception
Authors: Martin M.G.F.
Published: September 2018

Sense perception is the use of our senses to acquire information about the world around us and to become acquainted with objects, events, and their features. Traditionally, there are taken to be five senses: sight, touch, hearing, smell and taste.

Philosophical debate about perception is ancient. Much debate focuses on the contrast between appearance and reality. We can misperceive objects and be misled about their nature, as well as perceive them to be the way that they are: you could misperceive the shape of the page before you, for example. Also, on occasion, it may seem to us as if we are perceiving, when we do not perceive at all, but only suffer hallucinations.

Illusions and hallucinations present problems for a theory of knowledge: if our senses can mislead us, how are we to know that things are as they appear, unless we already know that our senses are presenting things as they are? But the concern in the study of perception is primarily to explain how we can both perceive and misperceive how things are in the world around us. Some philosophers have answered this by supposing that our perception of material objects is mediated by an awareness of mind-dependent entities or qualities: typically called sense-data, ideas or impressions. These intermediaries allegedly act as surrogates or representatives for external objects: when they represent aright, we perceive; when they mislead, we misperceive.

An alternative is to suppose that perceiving is analogous to belief or judgment: just as judgment or belief can be true or false, so states of being appeared to may be correct or incorrect. This approach seeks to avoid intermediary objects between the perceiver and the external objects of perception, while still taking proper account of the possibility of illusion and hallucination. Both responses contrast with that of philosophers who deny that illusions and hallucinations have anything to tell us about the nature of perceiving proper, and hold to a form of naïve, or direct, realism.

The account of perception one favours has a bearing on one’s views of other aspects of the mind and world: the nature and existence of secondary qualities, such as colours and tastes; the possibility of giving an account of the mind as part of a purely physical, natural world; how one should answer scepticism concerning our knowledge of the external world.
Pleasure
Authors: Marshall Graeme
Published: September 2018

From Plato and beyond, pleasure has been thought to be a basic, and sometimes the only basic, reason for doing anything. Since there are many forms that pleasure can take and many individual views of what pleasure consists in, much attention has been given to how pleasures may be distinguished, what their motivational and moral significance might be, and whether there may not be some objective determination of them, whether some may be good or bad, or some better as pleasures than others.

But first there is the question of what pleasure is. It has been variously thought to be a state of mind like distress only of the opposite polarity; merely the absence or cessation of or freedom from pain; a kind of quiescence like contentment; or the experiencing of bodily sensations which, unlike sensations of pain, one does not want to stop. We also identify and class together particular sources of pleasure and call them pleasures of the table, company, sex, conversation, solitude, competition, contemplation or athletic pleasures. In this sense there may be some pleasures which we do not enjoy. But most generally pleasure is what we feel and take when we do enjoy something. This raises the questions of what is encompassed by ’something’, what it is to enjoy anything, and the extent to which theories of pleasure can accommodate both our passivity and activity in pleasure. The most influential theories have been those of Plato, Aristotle and empiricists such as Hume and Bentham.
Reductionism in the philosophy of mind
Authors: Sterelny Kim
Published: September 2018

Reductionism in the philosophy of mind is one of the options available to those who think that humans and the human mind are part of the natural physical world. Reductionists seek to integrate the mind and mental phenomena – fear, pain, anger and the like – with the natural world by showing them to be natural phenomena. Their inspirations are the famous reductions of science: of the heat of gases to molecular motion, of lightning to electric discharge, of the gene to the DNA molecule and the like. Reductionists hope to show a similar relationship between mental kinds and neurophysiological kinds.
Self-deception
Authors: Mele Alfred R.
Published: September 2018

Philosophical work on self-deception revolves around a trio of questions. What is self-deception? Is self-deception possible? How are cases of self-deception to be explained? The extent to which self-deception is analogous to interpersonal deception is controversial, partly because certain analogies threaten to render the possibility of self-deception deeply problematic. The problems concern both the mental state of self-deceived individuals at a particular time (static problems) and the dynamics of self-deception (dynamic problems). For example, in normal interpersonal deception the deceivers know something, p, or at least believe truly that p, while getting their victims to believe the opposite, ∼p. So if self-deception is strictly analogous to (normal) interpersonal deception, self-deceivers know or believe truly that p while getting themselves to believe that ∼p. If this entails simultaneously believing that p and believing that ∼p, self-deception may seem impossible. (For example, how can I believe that someone will read this entry while also believing that no one will read it?) Moreover, even if this state is possible, the suggestion that people can get themselves into it by deceiving themselves is problematic. It may seem, for instance, that any project describable as ‘getting myself to believe what I now know to be false’ is bound to be self-defeating. Self-deception may be dynamically impossible.
Self-deception
Authors: Mele Alfred R.
Published: September 2018

Philosophical work on self-deception revolves around a trio of questions. What is self-deception? Is self-deception possible? How are instances of self-deception to be explained? The extent to which self-deception is analogous to interpersonal deception is controversial, partly because certain analogies threaten to render the possibility of self-deception deeply problematic. The problems concern both the mental state of self-deceived individuals at a particular time (static problems) and the dynamics of self-deception (dynamic problems). For example, in normal interpersonal deception the deceivers know something, p, or at least believe truly that p, while getting their victims to believe the opposite, ~ p. So if self-deception is strictly analogous to normal interpersonal deception, self-deceivers know or believe truly that p while getting themselves to believe that ~ p. If this entails simultaneously believing that p and believing that ~ p, self-deception may seem impossible. (For example, how can I believe that my sister will read this entry while also believing that she will not?) Moreover, even if this state is possible, the suggestion that people can get themselves into it by deceiving themselves is problematic. It may seem, for instance, that any project describable as ‘getting myself to believe what I now know to be false’ is bound to be self-defeating. Self-deception may be dynamically impossible.
Linguistics, philosophy of
Authors: Rey Georges , Blair Dan
Published: September 2018

Although related to issues in the philosophy of language, the philosophy of linguistics is a largely distinct topic, being concerned not so much with language itself but with the character and significance of scientific theories about it, for example, with the ontology of linguistic entities, and with whether linguistics is properly regarded as a branch of psychology or as of a kind of mathematics. The work of Ferdinand de Saussure and Roman Jacobson initiated interest in many of these topics, leading to the structuralist movement in Continental Europe, but it was the work of Noam Chomsky that later sparked the cognitive revolution in Anglo-American philosophy and psychology. Chomsky argued that linguistics should not be concerned with the actual performance of speakers, but instead with the underlying system of rules that was responsible for the competence to produce and understand those utterances. Calling attention to a stunning array of data, he went on to argue that linguistic theory should be concerned with the innately specified system that enabled young children to acquire that competence so effortlessly in a remarkably short time. This claim he linked to the tradition of philosophical Rationalism, according to which substantial portions of human knowledge are not obtained from experience, as Empiricists had maintained, but are largely innate. These and related claims have occasioned important exchanges with a number of philosophers about the foundations of language and mind.
Artificial intelligence
Authors: Boden Margaret A.
Published: September 2018

Artificial intelligence (AI) tries to make computer systems (of various kinds) do what minds can do: interpreting a photograph as depicting a face; offering medical diagnoses; using and translating language; learning to do better next time.

AI has two main aims. One is technological: to build useful tools, which can help humans in activities of various kinds, or perform the activities for them. The other is psychological: to help us understand human (and animal) minds, or even intelligence in general.

Computational psychology uses AI concepts and AI methods in formulating and testing its theories. Mental structures and processes are described in computational terms. Usually, the theories are clarified, and their predictions tested, by running them on a computer program. Whether people perform the equivalent task in the same way is another question, which psychological experiments may help to answer. AI has shown that the human mind is more complex than psychologists had previously assumed, and that introspectively ‘simple’ achievements – many shared with animals – are even more difficult to mimic artificially than are ’higher’ functions such as logic and mathematics.

There are deep theoretical disputes within AI about how best to model intelligence. Classical (symbolic) AI programs consist of formal rules for manipulating formal symbols; these are carried out sequentially, one after the other. Connectionist systems, also called neural networks, perform many simple processes in parallel (simultaneously); most work in a way described not by lists of rules, but by differential equations. Hybrid systems combine aspects of classical and connectionist AI. More recent approaches seek to construct adaptive autonomous agents, whose behaviour is self-directed rather than imposed from outside and which adjust to environmental conditions. Situated robotics builds robots that react directly to environmental cues, instead of following complex internal plans as classical robots do. The programs, neural networks and robots of evolutionary AI are produced not by detailed human design, but by automatic evolution (variation and selection). Artificial life studies the emergence of order and adaptive behaviour in general and is closely related to AI.

Philosophical problems central to AI include the following. Can classical or connectionist AI explain conceptualization and thinking? Can meaning be explained by AI? What sorts of mental representations are there (if any)? Can computers, or non-linguistic animals, have beliefs and desires? Could AI explain consciousness? Might intelligence be better explained by less intellectualistic approaches, based on the model of skills and know-how rather than explicit representation?
Chinese room argument
Authors: Gulick Robert Van
Published: September 2018

John Searle’s ‘Chinese room’ argument aims to refute ‘strong AI’ (artificial intelligence), the view that instantiating a computer program is sufficient for having contentful mental states. Imagine a program that produces conversationally appropriate Chinese responses to Chinese utterances. Suppose Searle, who understands no Chinese, sits in a room and is passed slips of paper bearing strings of shapes which, unbeknown to him, are Chinese sentences. Searle performs the formal manipulations of the program and passes back slips bearing conversationally appropriate Chinese responses. Searle seems to instantiate the program, but understands no Chinese. So, Searle concludes, strong AI is false.
Folk psychology
Authors: Stich Stephen P. , Rey Georges
Published: September 2018

There is wide disagreement about the meaning of ordinary mental terms (such as ‘belief’, ‘desire’, ‘pain’). Sellars suggested that our use of these terms is governed by a widely shared theory, ‘folk psychology’, a suggestion that has gained empirical support in psychological studies of self-attribution and in a growing literature concerning how children acquire (or, in the case of autism, fail to acquire) ordinary mental concepts. Recently, there has been a lively debate about whether people actually ‘theorize’ about the mind, or, instead, engage in some kind of ‘simulation’ of mental processes.
Cognition, infant
Authors: Gopnik Alison , Meltzoff Andrew N.
Published: September 2018

In the past thirty years developmental psychologists have developed techniques for investigating the cognitive resources of infants. These techniques show that an infant’s initial representation of the world is richer and more abstract than traditional empiricists supposed. For instance, infants seem to have at least some understanding of distance, of the continued existence of objects which are out of sight, and of the mental states of others. Such results have led philosophers to reconsider the idea – to be found in Plato – that there may be innate constraints on the way we view the world, and to examine the extent to which innate ‘knowledge’ may be revised as a result of learning.
Content, indexical
Authors: Bach Kent
Published: September 2018

Many of our thoughts are about particular individuals (persons, things, places,…). For example, one can spot a certain Ferrari and think that it is red. What enables this thought to latch onto that particular object? It cannot be how the Ferrari looks, for this could not distinguish one Ferrari from another just like it. In general, how a thought represents something cannot determine which thing it represents. What a singular thought latches onto seems to depend also on features of the context in which the thought occurs. This suggests that its content is essentially indexical, contextually variable much as the content of an utterance such as ‘I am hungry’ depends on who utters it and when. The indexical model of singular thought is not limited to thoughts about individuals one perceives, but applies also to thoughts about individuals one remembers or has been informed of, such as an old bicycle or Christopher Columbus. In each case, a certain contextual relation, based on perception, memory or communication, connects thought to object.
Introspection, psychology of
Authors: Von Eckhardt Barbara
Published: September 2018

Introspection is the process of directly examining one’s own conscious mental states and processes. Since the seventeenth century, there has been considerable disagreement on the scope, nature and epistemic status of introspection. Descartes held that all our mental states are subject to introspection; that it is sufficient to have a mental state to be aware of it; and that when we introspect, we cannot be mistaken about what we introspectively observe. Each of these views has been disputed. Nineteenth-century psychology relied heavily on introspection, but with the exception of important work in psychophysics and perception, it is now primarily of historical interest. Recently, Nisbett and Wilson have argued that when people attempt to report on the processes mediating the effects of a stimulus on a response, they do not do so on the basis of introspection but, rather, on the basis of an implicit common-sense ‘theory’. Ericsson and Simon have developed a model of the mechanisms by which ‘introspective’ reports are generated and have used that model to identify the conditions under which such reports are reliable.
Methodological individualism
Authors: Segal Gabriel
Published: September 2018

Methodological individualism (MI) is the thesis that certain psychological properties are intrinsic properties, such as ‘being made out of iron’, rather than externally relational properties, such as ‘being an aunt’. It has been challenged by influential ‘anti-individualist’ claims of, for example, Putnam and Burge, according to which the content of an individual’s words or thoughts (beliefs, desires) is determined in part by facts about their social or physical environment. Putnam, for example, imagines a planet, ‘twin earth’, which is identical to the earth in 1750 (prior to modern chemistry) in all respects except that wherever earth had H2O, twin earth had a different but superficially similar chemical, XYZ. Putnam argues that the English word ‘water’ in 1750 referred only to H2O, while the twin word ‘water’ refers only to XYZ.

Historically, the term ‘methodological individualism’ has referred to the thesis that all social explanation must be ultimately expressible in terms of facts about individual human beings; not about economic classes, nations and so on. For a treatment of this subject, see Explanation in history and social science §1.
Nativism
Authors: Samet Jerry
Published: September 2018

Traditional empiricism claims that the mind is initially equipped only with the capacity for experience and the mechanisms that make it possible for us to learn from experience. Nativists have argued that this is not enough, and that our innate endowment must be far richer, including information, ideas, beliefs, perhaps even knowledge.

Empiricism held the advantage until recently, partly because of a misidentification of nativism with rationalism. Rationalists such as Descartes and Leibniz thought nativism would explain how a priori knowledge of necessary truths is possible. However, the fact that something is innate does not establish that it is true, let alone that it is necessary or a priori.

More recently, nativism has been reanimated by Chomsky’s claims that children must have innate language-specific information that mediates acquisition of their native tongue. He argues that, given standard empiricist learning procedures, the linguistic data available to a child underdetermines the grammar on which they converge at a very young age, with relatively little effort or instruction.

The successes in linguistics have led to fruitful research on nativism in other domains of human knowledge: for example, arithmetic, the nature of physical objects, features of persons, and possession of concepts generally.
Parapsychology
Authors: Stairs Allen
Published: September 2018

Tales of dreams that come true, ‘mind over matter’ and other such oddities are both familiar and old. Parapsychology investigates such things, attempting to use scientific and, especially, experimental methods to investigate whether and in what circumstances humans can glean information without using ordinary perceptual means (that is, by extrasensory perception or ESP) or can alter the physical environment simply by willing it (that is, by psychokinesis). Such phenomena, if they exist, are often grouped under the heading psi(-phenomena).

It is sometimes claimed that parapsychology presents a challenge to physicalism. However, ostensible psi-phenomena are known through their physical effects and are studied within parapsychology by ordinary scientific methods. In fact, models intended to explain psi-phenomena by known physical processes have been seriously discussed within parapsychology. In any case, parapsychology alone could not show that psi-phenomena have no physical explanation; that is a judgment for physics itself. More important, physicalism is a very broad doctrine that should not simply be equated with the requirement that everything be explained within physics. It is very unclear what we would gain by denying that psi-phenomena are physical.
Piaget, Jean (1896–1980)
Authors: Gopnik Alison
Published: September 2018

The Swiss psychologist Jean Piaget was the founder of the field we now call cognitive development. His own term for the discipline was ‘genetic epistemology’, reflecting his deep philosophical concerns. Among Piaget’s most enduring contributions were his remarkably robust and surprising observations of children. Time after time, in a strikingly wide variety of domains, and at every age from birth to adolescence, he discovered that children understood the world in very different ways from adults.

But Piaget was really only interested in children because he thought they exemplified basic epistemological processes. By studying children we could discover how biological organisms acquire knowledge of the world around them. The principles of genetic epistemology could then be applied to other creatures, from molluscs to physicists. Piaget’s other enduring legacy is the idea that apparently foundational kinds of knowledge were neither given innately nor directly derived from experience. Rather, knowledge was constructed as a result of the complex interplay between organisms and their environment. Piaget saw this view as an alternative to both classical rationalism and empiricism.
Semantics, conceptual role
Authors: Block Ned
Published: September 2018

According to conceptual role semantics (CRS), the meaning of a representation is the role of that representation in the cognitive life of the agent, for example, in perception, thought and decision-making. It is an extension of the well-known ‘use’ theory of meaning, according to which the meaning of a word is its use in communication and, more generally, in social interaction. CRS supplements external use by including the role of a symbol inside a computer or a brain. The uses appealed to are not just actual, but also counterfactual: not only what effects a thought does have, but what effects it would have had if stimuli or other states had differed. Of course, so defined, the functional role of a thought includes all sorts of causes and effects that are non-semantic, for example, perhaps happy thoughts can bolster one’s immunity, promoting good health. Conceptual roles are functional roles minus such non-semantic causes and effects.

The view has arisen separately in philosophy (where it is sometimes called ‘inferential’ or ‘functional’ role semantics) and in cognitive science (where it is sometimes called ‘procedural semantics’).
Skinner, Burrhus Frederick (1904–90)
Authors: Flanagan Owen , Rey Georges
Published: September 2018

B.F. Skinner advocated a philosophy of psychology, called ‘radical behaviourism’, as well as a substantive psychological theory, ‘scientific behaviourism’. Radical behaviourism restricted psychology to establishing lawful links between the environment and behaviour, rejecting the ‘mind’ as a ‘needless way station’ mediating the two. Scientific behaviourism proposed specific links, the laws of ‘operant conditioning’, whereby behaviours are ‘reinforced’ by the consequences they have had in an animal’s past. Although Skinner brought to psychology new standards of experimental rigour, and managed to train animals to do remarkable things, there are serious limits to the range of behaviours scientific behaviourism can explain. Both it and radical behaviourism have been obviated by the development of a computational theory of mind.
Supervenience of the mental
Authors: Loewer Barry
Published: September 2018

Phenomena of one kind ‘supervene on’ phenomena of another kind just in case differences with respect to the first kind require differences with respect to the second. G.E. Moore claimed that beauty supervenes on non-aesthetic properties: if one painting is beautiful and another is not, there must be some relevant non-aesthetic difference between them. Supervenience seems to offer the possibility that a property may depend on other properties, without being explicable in terms of them. Contemporary philosophers of mind have employed the idea to capture the relation that appears to obtain between mental and physical properties.
Syntax
Authors: Neale Stephen
Published: September 2018

Syntax (more loosely, ‘grammar’) is the study of the properties of expressions that distinguish them as members of different linguistic categories, and ‘well-formedness’, that is, the ways in which expressions belonging to these categories may be combined to form larger units. Typical syntactic categories include noun, verb and sentence. Syntactic properties have played an important role not only in the study of ‘natural’ languages (such as English or Urdu) but also in the study of logic and computation. For example, in symbolic logic, classes of well-formed formulas are specified without mentioning what formulas (or their parts) mean, or whether they are true or false; similarly, the operations of a computer can be fruitfully specified using only syntactic properties, a fact that has a bearing on the viability of computational theories of mind.

The study of the syntax of natural language has taken on significance for philosophy in the twentieth century, partly because of the suspicion, voiced by Russell, Wittgenstein and the logical positivists, that philosophical problems often turned on misunderstandings of syntax (or the closely related notion of ‘logical form’). Moreover, an idea that has been fruitfully developed since the pioneering work of Frege is that a proper understanding of syntax offers an important basis for any understanding of semantics, since the meaning of a complex expression is compositional, that is, built up from the meanings of its parts as determined by syntax.

In the mid-twentieth century, philosophical interest in the systematic study of the syntax of natural language was heightened by Noam Chomsky’s work on the nature of syntactic rules and on the innateness of mental structures specific to the acquisition (or growth) of grammatical knowledge. This work formalized traditional work on grammatical categories within an approach to the theory of computability, and also revived proposals of traditional philosophical rationalists that many twentieth-century empiricists had regarded as bankrupt. Chomskian theories of grammar have become the focus of most contemporary work on syntax.
Turing, Alan Mathison (1912–54)
Authors: Moor James H.
Published: September 2018

Alan Turing was a mathematical logician who made fundamental contributions to the theory of computation. He developed the concept of an abstract computing device (a ‘Turing machine’) which precisely characterizes the concept of computation, and provided the basis for the practical development of electronic digital computers beginning in the 1940s. He demonstrated both the scope and limitations of computation, proving that some mathematical functions are not computable in principle by such machines.

Turing believed that human behaviour might be understood in terms of computation, and his views inspired contemporary computational theories of mind. He proposed a comparative test for machine intelligence, the ‘Turing test’, in which a human interrogator tries to distinguish a computer from a human by interacting with them only over a teletypewriter. Although the validity of the Turing test is controversial, the test and modifications of it remain influential measures for evaluating artificial intelligence.
Unconscious mental states
Authors: Rey Georges
Published: September 2018

Unconscious phenomena are those mental phenomena which their possessor cannot introspect, not only at the moment at which the phenomenon occurs, but even when prompted (‘Do you think/want/…?’). There are abundant allusions to many kinds of unconscious phenomena from classical times to Freud. Most notably, Plato in his Meno defended a doctrine of anamnesis according to which a priori knowledge of, for example, geometry is ‘recollected’ from a previous life. But the notion of a rich, unconscious mental life really takes hold in nineteenth-century writers, such as Herder, Hegel, Helmholtz and Schopenhauer. It is partly out of this latter tradition that Freud’s famous postulations of unconscious, ‘repressed’ desires and memories emerged.

Partly in reaction to the excesses of introspection and partly because of the rise of computational models of mental processes, twentieth-century psychology has often been tempted by Lashley’s view that ‘no activity of mind is ever conscious’ (1956). A wide range of recent experiments do suggest that people can be unaware of a multitude of sensory cognitive factors (for example, pupillary dilation, cognitive dissonance, subliminal cues to problem-solving) that demonstrably affect their behaviour. And Weiskrantz has documented cases of ‘blindsight’ in which patients with damage to their visual cortex can be shown to be sensitive to visual material they sincerely claim they cannot see.

The most controversial cases of unconscious phenomena are those which the agent could not possibly introspect, even in principle. Chomsky ascribes unconscious knowledge of quite abstract principles of grammar to adults and even newborn children that only a linguist could infer.

Many philosophers have found these claims about the unconscious unconvincing, even incoherent. However, they need to show how the evidence cited above could be otherwise explained, and why appeals to the unconscious have seemed so perfectly intelligible throughout history.
Simulation theory
Authors: Davis Martin , Stone Tony
Published: September 2018

Mental simulation is the simulation, replication or re-enactment, usually in imagination, of the thinking, decision-making, emotional responses or other aspects of the mental life of another person. According to simulation theory, mental simulation in imagination plays a key role in our everyday psychological understanding of other people. The same mental resources that are used in our own thinking, decision-making or emotional responses are redeployed in imagination to provide an understanding of the thoughts, decisions or emotions of another.

Simulation theory stands opposed to the ’ theory theory’ of folk psychology. According to the theory theory, everyday psychological understanding depends on deployment of an empirical theory or body of information about psychological matters, such as how people normally think, make decisions or respond emotionally. Simulation theory does not altogether deny that third-personal psychological knowledge is implicated in our folk psychological practice, prediction, interpretation and explanation. But it maintains that, over a range of cases, the first-personal methodology of mental simulation allows us to avoid the need for detailed antecedent knowledge about how psychological processes typically operate.
Mirror self-recognition
Authors: Schilhab Theresa
Published: September 2018

Mirror self-recognition (MSR) refers to the empirical investigation of self-awareness, also known as the ‘mirror and mark test’ introduced by psychologist Gordon G. Gallup (1970). The ability to direct behaviour to previously unseen parts of the body such as the inside of the mouth or to groom the eye by the aid of mirrors has been interpreted as the recognition of the self and evidence of a self-concept. Unknowingly, a similar approach was developed independently with children (Amsterdam 1972).

The successful passing of the mirror and mark test has been widely used as a benchmark for distinguishing conscious and non-conscious species within fields with a general interest in evolutionary perspectives on consciousness and cognition such as comparative psychology and cognitive ethology, although controversies about the methodology and theoretical framework persist. These disputes question our intuitions about consciousness and accentuate the epistemic difficulty of obtaining evidence on mental states in others.
Intersubjectivity
Authors: Spaulding Shannon
Published: September 2018

Intersubjectivity is the shared or mutual understanding among agents. Edmond Husserl first developed the concept of intersubjectivity as a critique of René Descartes’ problem of other minds. Husserl argued that the problem of other minds portrayed human interaction as inappropriately solipsistic. More recently, the concept of intersubjectivity has played a role in phenomenological accounts of social cognition, embodied and enactive cognition, debates about whether we can directly perceive others’ mental states, collective intentionality, and group minds.
Free logics, philosophical issues in
Authors: Lambert Karel
Published: September 2018

The expression ‘free logic’ is a contraction of the more cumbersome ‘logic free of existence assumptions with respect to both its general terms (predicates) and its singular terms’. Its most distinctive feature is the rejection of the principle of universal specification, a principle of classical predicate logic which licenses the logical truth of statements such as ‘If everything rotates then (the planet) Mars rotates’. If a free logic contains the general term ‘exists’, this principle is replaced by a restricted version, one which licenses the logical truth only of statements such as ‘If everything rotates then Mars rotates, provided that Mars exists’. If the free logic does not contain the general term ‘exists’, but contains the term ‘is the same as’, the principle is replaced by a version which licenses only statements such as ‘If everything rotates then Mars rotates, provided that there is an object the same as Mars’.

Most free logicians regard the restricted version of universal specification as simply making explicit an implicit assumption, namely, that Mars exists. Indeed, free logic is the culmination of a long historical trend to rid logic of existence assumptions with respect to its terms. Just as classical predicate logic purports to be free of the hidden existence assumptions which pervaded the medieval theory of inference with respect to its general terms, so free logic rids classical predicate logic of hidden existence assumptions with respect to its singular terms.

There are various kinds of free logic, with many interesting and novel philosophical applications. These cover a wide range of issues from the philosophy of mathematics to the philosophy of religion. In addition to the issue of how to analyse singular existence statements, of the form ‘3 + 7 exists’ and ‘That than which nothing greater can be conceived exists’, of special importance are issues in the theory of definite descriptions, set theory, the theory of reference, modal logic and the theory of complex general terms.
Second-order logic, philosophical issues in
Authors: Shapiro Stewart
Published: September 2018

Typically, a formal language has variables that range over a collection of objects, or domain of discourse. A language is ‘second-order’ if it has, in addition, variables that range over sets, functions, properties or relations on the domain of discourse. A language is third-order if it has variables ranging over sets of sets, or functions on relations, and so on. A language is higher-order if it is at least second-order.

Second-order languages enjoy a greater expressive power than first-order languages. For example, a set S of sentences is said to be categorical if any two models satisfying S are isomorphic, that is, have the same structure. There are second-order, categorical characterizations of important mathematical structures, including the natural numbers, the real numbers and Euclidean space. It is a consequence of the Löwenheim–Skolem theorems that there is no first-order categorical characterization of any infinite structure. There are also a number of central mathematical notions, such as finitude, countability, minimal closure and well-foundedness, which can be characterized with formulas of second-order languages, but cannot be characterized in first-order languages.

Some philosophers argue that second-order logic is not logic. Properties and relations are too obscure for rigorous foundational study, while sets and functions are in the purview of mathematics, not logic; logic should not have an ontology of its own. Other writers disqualify second-order logic because its consequence relation is not effective – there is no recursively enumerable, sound and complete deductive system for second-order logic.

The deeper issues underlying the dispute concern the goals and purposes of logical theory. If a logic is to be a calculus, an effective canon of inference, then second-order logic is beyond the pale. If, on the other hand, one aims to codify a standard to which correct reasoning must adhere, and to characterize the descriptive and communicative abilities of informal mathematical practice, then perhaps there is room for second-order logic.
Demonstratives and indexicals
Authors: Deutsch Harry
Published: September 2018

Demonstratives and indexicals are words and phrases whose interpretations are dependent on features of the context in which they are used. For example, the reference of ‘I’ depends on conditions associated with its use: as you use it, it refers to you; as I use it, it refers to me. In contrast, what ‘the inventor of bifocals’ refers to does not depend on when or where or by whom it is used. Among indexicals are the words ‘here’, ‘now’, ‘today’, demonstrative pronouns such as ‘this’, reflexive, possessive and personal pronouns; and compound phrases employing indexicals, such as ‘my mother’. C.S. Peirce introduced the term ‘indexical’ to suggest the idea of pointing (as in ‘index finger’).

The phenomenon of indexicality figures prominently in recent debates in philosophy. This is because indexicals allow us to express beliefs about our subjective ‘place’ in the world, beliefs which are the immediate antecedents of action; and some argue that such beliefs are irreducibly indexical. For example, my belief that I am about to be attacked by a bear is distinct from my belief that HD is about to be attacked by a bear, since my having the former belief explains why I act as I do (I flee), whereas my having the latter belief explains nothing unless the explanation continues ‘and I believe that I am HD’. It seems impossible to describe the beliefs that prompt my action without the help of ‘I’. Similarly, some have argued that indexical-free accounts of the self or of consciousness are necessarily incomplete, so that a purely objective physicalism is impossible. In a different vein, some (such as Putnam 1975) have argued that our terms for natural substances, kinds and phenomena (‘gold’, ‘water’, ‘light’) are indexical in a way that entails that certain substantive scientific claims – for example, that water is H2O – are, if true, necessarily true. Thus, reflection on indexicality has yielded some surprising (and controversial) philosophical conclusions.
Existence
Authors: Mackie Penelope
Published: September 2018

Philosophical problems concerning existence fall under two main headings: ‘What is existence?’ and ‘What things exist?’. Although these questions cannot be entirely separated, this entry will concentrate on the first.

The question ‘What is existence?’ has produced a surprising variety of answers. Some hold that existence is a property that every individual has, others that it is a characteristic that some individuals have but other (for example, imaginary) individuals lack, while proponents of the thesis that ‘existence is not a predicate’ hold that existence is not a property or characteristic of individuals at all.

Other philosophical issues concerning existence include: disputes about whether there are abstract objects (for example, numbers, universals) as well as concrete ones, immaterial souls as well as bodies, possible objects as well as actual ones, and so on; and questions about which entities (if any) are the fundamental constituents of reality.
Formal and informal logic
Authors: Walton Douglas
Published: September 2018

Formal logic abstracts the form of an argument from an instance of it that may be encountered, and then evaluates the form as being valid or invalid. The form is the important thing, rather than the concrete instance of the form. Informal logic, on the other hand, evaluates how an argument is used in a given context of conversation. This more practical, real-world orientation requires more judgment in interpreting what a given text of discourse should be taken to argue.