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Most contemporary philosophers of mind regard belief as a propositional attitude.  Propositional attitudes are held to be mental states having the canonical formulation ‘S A that P’, where ‘S’ refers to the entity possessing the mental state, ‘A’ expresses the general type of attitude, and ‘P’ expresses a proposition by means of a complete sentence.  For example: ‘Roshini [the subject] believes [the attitude] that snow is white [the proposition]’; or ‘Jake [the subject] hopes [the attitude] that Kelli kissed Ahmed [the proposition]’.  Besides belief, other widely discussed propositional attitudes include desire and intention.  The full list of propositional attitudes is generally viewed as extensive.

Philosophers willing to describe belief as a propositional attitude hold a wide variety of views about the nature of propositions (see propositions, singular; propositions, structured), including the view that propositions don’t actually exist, and to a considerable extent the debate about the nature of propositions runs separately from the debate about the nature of propositional attitudes such as belief.  At a minimum, a proposition is supposed to be whatever it is that is expressed by a sentence, such that, when two people say the same thing by uttering different sentences, they are expressing the same proposition.  Thus, if Roshini says ‘snow is white’ in English and Uta says ‘Schnee ist weiss’ in German, they are generally thought to be saying the same thing or expressing the same proposition.  Correspondingly, ‘Roshini believes that snow is white’ is supposed to attribute the same belief to Roshini that ‘Uta glaubt, dass Schnee weiss ist’ attributes to Uta.  Likewise, if ‘Kelli kissed Ahmed’ and ‘Ahmed was kissed by Kelli’ express the same proposition, ‘Jake believes that Kelli kissed Ahmed’ and ‘Jake believes that Ahmed was kissed by Kelli’ attribute the same belief.

Although ‘belief’ is not a high-frequency word in everyday English and may ordinarily connote considered opinion on a topic of broad significance (as in ‘religious beliefs’ or ‘the belief that all people are created equal’), analytic philosophers of mind generally use the term more broadly to capture the attitude often expressed by English sentences of the form ‘S thinks that P’.  This broad usage of ‘belief’ avoids the ambiguity inherent in the word ‘thinks’ between what we might call currently entertaining an idea (often expressed by the progressive ‘is thinking’, as in ‘Xinyan is thinking about Beijing’) and what we might call taking a particular proposition to be true (as in ‘Eli thinks that waking early is a healthy habit’, which can be true even if Eli is not currently pondering the matter).  The nominal form ‘thought’ may then be reserved for thinking in the first sense and the nominal form ‘belief’ for thinking in the second sense.

The Representational Approach

It is natural to think of believing as involving entities, beliefs, that are in some sense contained in the mind.  When someone learns a particular fact, for example, when Kai learns that many astronomers no longer classify Pluto as a planet, he or she acquires a new belief -- in this case, Kai acquires the belief that many astronomers no longer classify Pluto as a planet.  The fact in question -- or, more accurately, a representation, symbol, or characterization of that fact -- may be stored in memory and accessed or recalled when necessary.  To have a fact represented in the mind in this way is to possess the corresponding belief.

It is also natural to suppose that beliefs play a causal role in the production of behavior.  Continuing the example, we might imagine that after learning about the potential demotion of Pluto, Kai naturally gets absorbed in other interests and does not consciously consider the matter for several days, until reading his son's science textbook he encounters the sentence "our solar system contains nine planets".  Involuntarily, his new knowledge about Pluto is called up from memory.  He finds himself doubting the truth of the textbook's claim, and he says, "actually, there's some dispute about that".  It seems plausible to say that Kai's belief about Pluto, or his possession of that belief, caused, or figured in a causal explanation of, his utterance.

Various elements of this intuitive characterization of belief have been challenged by philosophers, but it is probably fair to say that the majority of contemporary philosophers of mind accept the bulk of this picture.  A cluster of approaches here termed representational tend to comport rather naturally with it.

Representational approaches to belief hold that central cases of belief involve S's having in his or her head or mind a representation with the content P.  (Perhaps in peripheral cases beliefs need not be underwritten by explicit representations: For example, if Kai believes that the number of planets is eight, a representationalist might grant that it is accurate to describe him as believing that the number of planets is less than eleven even if Kai's mind does not contain an explicit representation with that content.)  Representationalists may disagree about what exactly is involved in having a representation with a particular content, and they may disagree about what further conditions, besides possessing such a representation, are necessary if a being is to qualify as having a belief.

One version of the representational approach, advocated by Jerry Fodor among others, takes mental representations to be sentences in an internal language of thought.  To get a sense of what this view amounts to, it is helpful to start with an analogy.  Computers are sometimes characterized as operating by manipulating sentences in "machine language" in accordance with certain rules.  Consider a simplified description of what happens as one enters numbers into a spreadsheet.  Inputs from the keyboard cause the computer, depending on the programs it is running and its internal state, to instantiate or "token" a sentence (in machine language) with the content (translated into English) of, for example, "numerical value 4 in cell A1".  In accordance with certain rules, the machine then displays the shape "4" in a certain location on the monitor, and perhaps, if it is implementing the rule "the values of column B are to be twice the values of column A", it tokens the sentence "numerical value 8 in cell B1" and displays the shape "8" in another location on the monitor.

Perhaps eventually (though it is a matter of dispute), we will be able to construct a robot whose behavior resembles that of a human being.  One might also imagine that this robot operates along broadly the lines described above: by manipulating machine-language sentences in accordance with rules, in connection with various potential inputs and outputs.  If we can imagine this, then perhaps we can also imagine the robot to store a variety of sentences in machine language corresponding to the ordinary beliefs of human beings.  For example, it might somewhere store the machine-language sentence whose English translation is "the chemical formula for water is H2O".  The robot is able to act as does a human who possesses this belief because it is disposed to access this sentence on relevant occasions: When asked "of what chemicals is water compounded?", the robot accesses the water sentence and manipulates it and other relevant sentences in such a way that it produces a human-like response.

According to the language of thought hypothesis, our cognition proceeds rather like such a robot's.  The formulae we manipulate are not in "machine language", of course, but rather in a species-wide "language of thought".  A sentence in the language of thought with the content P is a "representation" of P.  S stands in the "belief" relation to such a representation just in case the representation plays the right kind of role in S's cognitive economy.  That is, it must not merely be instantiated somewhere in the mind or brain, but it must be deployed, or apt to be deployed, in the kinds of roles that we regard as characteristic of belief.  For example, it must be apt to be called up for use in theoretical inferences toward which it is relevant.  It must be ready for appropriate deployment in deliberation about means to desired ends.  It is sometimes said, in such a case, that S has that proposition tokened in her “belief box” (though of course it is not assumed that there is any literal box-like structure in which S stores her all beliefs).

Another way of characterizing mental representations, not necessarily incompatible with regarding mental representations as sentences in the language of thought, centers on the idea of representational systems as systems with the function of tracking features of the world.  Organisms, especially mobile ones, generally need to keep track of features of their environment to be evolutionarily successful.  Consequently, they generally possess internal systems whose function it is to covary in certain ways with the environment.  For example, certain marine bacteria contain internal magnets that align with the Earth's magnetic field.  In the northern hemisphere, these bacteria, guided by the magnets, propel themselves toward magnetic north.  Since in the northern hemisphere magnetic north tends downward, they are thus carried toward deeper water and sediment, and away from toxic, oxygen-rich surface water.  We might thus say that the magnetic system of these bacteria is a representational system that functions to indicate the direction of benign or oxygen-poor environments.  (This example is due to Fred Dretske (1988), one of the principal articulators of the representational perspective on belief.)  In general, an organism can be said to represent P just in case that organism contains a subsystem whose function it is to enter state A only if P is true, and that subsystem is in state A.

Most representationalists would not regard magnetosome bacteria as having beliefs about magnetic north or oxygen-poor environments.  There is no consensus about precisely what additional further conditions, not satisfied by the bacteria, are necessary for possession of belief.  However, it is widely supposed that the further conditions involve something like the incorporation of the representational system into a larger set of sophisticated representational systems, possibly including systems that can represent representational systems themselves.

The Pattern/Interpretation Approach

Another group of philosophers treats the internal structure of the mind as of only incidental relevance to the question of whether a being is properly described as believing.  One way to highlight the difference is this: Imagine, in contravention of all known science, the existence of a being, Rudolfo, whose actual and potential behavior, and perhaps conscious experience, is perfectly normal by human standards but who has no internal structure of the relevant sort.  Perhaps all Rudolfo has inside is perfectly uniform balsa wood.  We are not to imagine that Rudolfo is a mere puppet controlled by some other intelligent organism or complex system, but rather that he is in the relevant sense self-moving.  Perhaps this scenario is not conceivable, but if it is, it would appear that we cannot properly say that Rudolfo manipulates sentences in the language of thought or possesses subsystems with indicator functions -- nor, indeed, apparently, can we say that his behavior is underwritten by mental representations at all.  Yet we might want to say, in virtue of Rudolfo's pattern of actual and potential behavior (and perhaps experience), that he believes things.

Representationalists need not deny this if they regard representationalism as a partly empirical hypothesis, as a hypothesis partly underwritten by observation of how organisms are actually constituted.  Nonetheless, the thought experiment displays the possibility of an approach to belief different from that of the representationalists, an approach here called the pattern/interpretation approach.  Advocates of the pattern/interpretation approach assert that S believes that P just in case S exhibits, or is disposed to exhibit, certain patterns of behavior -- the sort of behavior that ordinary non-philosophers tend to regard as characteristic of belief.  In response to the concern that any pattern of behavior could be faked by a talented enough actor, advocates of this view sometimes point out that the actor's and the true believer's behavioral dispositions are not in fact identical if one considers sufficiently remote conditions.  It may also be possible to avoid this objection by treating patterns of actual and potential conscious experience as on an equal footing with behavioral patterns.

The most straightforward form of the pattern/interpretation approach is dispositionalist or conditionalist.  On a dispositionalist or conditionalist view, for S to believe that P is for S to be possessed of one or more behavioral dispositions, or for one or more conditional statements to be true of S.  Often cited is the disposition to assent to utterances of P if circumstances are favorable in certain ways (that is, if one understands the language, wishes to reveal one's true opinion, is not physically incapacitated, etc.).  Other relevant dispositions might include the disposition to be, or to act, surprised should the falsity of P make itself evident; the disposition to conclude that Q if one is shown that P implies Q; and the disposition to depend on P's truth in formulating plans of action.  Perhaps these dispositions can all be brought under a single umbrella, which is, most generally, to behave as though P is the case.

Neither of the two most prominent recent advocates of the pattern/interpretation approach, Daniel Dennett and Donald Davidson, take a simple dispositionalist line.  If the motive of dispositionalism is reductive, that is, if dispositionalism aims to characterize mental states like belief and desire wholly in "more basic" terms, such as terms describing outwardly observable behavior, then it appears likely to fail.  The specification of the dispositions for any particular belief seems necessarily to involve appeal to a variety of other mental states, including other beliefs.  The dispositional specification of those beliefs would then require appeal to still more beliefs, and so forth, and it's not clear how this process could be brought to a happy conclusion.

To gain a sense of Dennett's view, consider three different methods we can use to predict the behavior of a human being.  The first method, which involves what Dennett calls taking the "physical stance", is to apply our knowledge of physical law.  We can predict that a diver will trace a roughly parabolic trajectory to the water because we know how objects of approximately that mass and size behave in fall near the surface of the Earth.  The second method, which involves taking the "design stance", is to attribute functions to the system or its parts and to predict that the system will function properly.  We can predict that a particular jogger's pulse will increase as she heads up the hill because of what we know about exercise and the proper function of the circulatory system.  The third method, which involves taking the "intentional stance", is to attribute beliefs and desires to the person, and then to predict that he or she will behave rationally, given those beliefs and desires.  It appears that much of our prediction of human behavior involves such attribution.  Treating people as mere physical bodies or as biological machines will not, as a practical matter, get us very far in social interaction.

On Dennett's view, a system with beliefs is a system whose behavior, while complex when viewed from the physical or the design stance, falls into patterns that may be captured with relative simplicity and substantial if not perfect accuracy by means of the intentional stance.  The system has the particular belief that P if its behavior conforms to a pattern that may be effectively captured by taking the intentional stance and attributing the belief that P.  Belief is thus characterized in terms of (pre-existing) practices of belief attribution.  Dennett acknowledges that his view has the unintuitive consequence that a sufficiently sophisticated chess-playing machine would have beliefs if its behavior is very complicated from the design stance (which would involve appeal to its programmed strategies) but predictable with relative accuracy and simplicity from the intentional stance (attributing the desire to defend its queen, the belief that you won't sacrifice a rook for a pawn, etc.).

Davidson also characterizes belief in terms of practices of belief attribution.  He invites us to imagine encountering a being with a wholly unfamiliar language and then attempting the task of constructing, from observation of the being's behavior in its environment, an understanding of that language.  Success in this enterprise would necessarily involve attributing beliefs and desires to the being in question, in light of which its utterances make sense.  An entity with beliefs is a being for whom such a project is practicable in principle -- a being that emits, or is disposed to emit, a complex pattern of behavior that can productively be interpreted as, in part, linguistic, rational, and expressive of its beliefs and desires.

Although pattern/interpretation approaches to belief treat behavioral (and possibly cognitive or experiential) patterns, rather than mental representations, as fundamental, the representational and pattern/interpretation approaches can be married if one holds that the existence of the relevant patterns implies, or is implied by, the possession of appropriate mental representations.  Dennett, for example, regards it as likely that the intentional stance works because cognition operates somewhat as defenders of the language of thought suppose.  Functionalism, also, which characterizes mental states in terms of their causal relations to inputs, outputs, and other mental states, can be given either a pattern/interpretationist or a representationalist cast, depending on what is emphasized.


Some philosophers have denied the existence of beliefs altogether.  This view, generally known as eliminativism, has been most prominently advocated by Paul Churchland and Stephen Stich (in his 1983 book; he subsequently moderated his opinion).  On this view, people's everyday conception of the mind, their "folk psychology", is a theory on par with folk theories about the origin of the universe or the nature of physical bodies.  And just as our pre-scientific theories on the latter topics were shown to be radically wrong by scientific cosmology and physics, so also will folk psychology, which is essentially still pre-scientific, be overthrown by scientific psychology and neuroscience once they have advanced far enough.

According to eliminativism, once folk psychology is overthrown, strict scientific usage will have no place for reference to most of the entities postulated by folk psychology, such as belief.  Beliefs, then, like "celestial spheres" or "phlogiston", will be judged not actually to exist, the mistaken posits of a radically false theory.  We may still find it convenient to speak of "belief" in informal contexts, if scientific usage is cumbersome, much as we still speak of "the sun going down", but if the concept of belief does not map onto the categories described by a mature scientific understanding of the mind, then literally speaking no one believes anything.


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behaviorism | cognitive science | consciousness and intentionality | Davidson, Donald | functionalism | intentionality | language of thought hypothesis | materialism, eliminative | memory | mental causation | mental content | mental content, causal theories of | mental content, externalism about | mental content, narrow | mental content, nonconceptual | mental content, teleological theories of | mental representation | mind, computational theory of | propositional attitude reports | propositions, singular | propositions, structured

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First published: September 30, 1995
Content last modified: October 30, 2002