Functionalism is a captivating concept, and on WHAT.EDU.VN, we can explore its depths together. Functionalism in the philosophy of mind states that a mental state depends on its function or role within a system, not its internal workings. This perspective offers a unique understanding of the mind.
Are you looking for explanations of what functionalism means to philosophy? Then keep reading to learn more, and remember, what.edu.vn can help you understand complex topics. This article delves into functionalist theories, their historical roots, and major criticisms, perfect for anyone curious about the philosophy of mind, mental state, and topic-neutral analysis.
1. What Does Functionalism Mean?
Functionalism defines a mental state, such as a thought or pain, by its function or role in a cognitive system rather than its internal makeup. This perspective emphasizes how sensory stimulations, other mental states, and behaviors causally relate to each other.
Imagine pain as a state triggered by bodily injury. It leads to the belief that something is amiss, the desire to escape that state, and anxiety, resulting in wincing or moaning unless stronger desires intervene. All beings with internal states that can perform this role are capable of feeling pain, and someone is in pain if they are in a state playing this role.
If neural activity like C-fiber stimulation plays this role in humans, then C-fiber stimulation allows humans to experience pain. However, this theory broadens the scope to include silicon-based Martians or inorganic androids that fulfill these conditions. Functionalists propose that pain can be realized differently across creatures, which means it is multiply realized. Since descriptions using only a state’s causal relations with stimulations, behavior, and other states are “topic-neutral”, mental states could be realized by non-physical states in some systems.
Functionalism is neutral between materialism and dualism but appeals more to materialists. Many believe physical states are more likely to play the required roles (Lewis, 1966). Functionalism offers a materialistic alternative to the Psycho-Physical Identity Thesis, which states that each mental state corresponds to a specific neural state. This thesis implies only creatures with human-like brains can share our sensations, beliefs, and desires. Functionalism counters this by suggesting mental states can be multiply realized, providing a more inclusive theory of the mind compatible with materialism (Block 1980b). However, some argue the identity thesis may be more inclusive than functionalists assume.
There are a few distinctions to be made within the functionalist description. In functionalist theories, functional characterizations of mental states provide analyses of the meanings of our mental state terms. Alternatively, the theories may restrict themselves to a priori information. Functional characterizations of mental states may use information from scientific experimentation or speculation (Shoemaker 1984c, Rey 1997). Other differences between functionalist theories are motivated by criticisms of the thesis and views about psychological explanation.
2. What Are The Backgrounds of Functionalism?
Functionalism as a mental state theory became prominent in the late 20th century but has roots in modern and ancient philosophy, computation, and artificial intelligence theories.
2.1 What Were Some Early Backgrounds?
Aristotle’s theory of the soul (350 BCE) is the earliest ancestor of functionalism. In contrast to Plato, Aristotle argued that the human soul is the form of an organized human body (De Anima Bk. II, Ch. 1). The soul is the powers or capacities that enable the body to express its “essential whatness” by fulfilling its function or purpose. The form of an ax is whatever enables it to cut, and the form of an eye is whatever enables it to see. Therefore, the human soul is identified with the capacities required for a body to live, perceive, reason, and act. Aristotle argues that the soul is inseparable from the body and comprises the capacities required for a body to live, perceive, reason, and act.
Hobbes’s (1651) account of reasoning is a second ancestor of functionalism. Hobbes describes reasoning as a calculation based on mechanistic principles similar to the rules of arithmetic. Reasoning is “nothing but reckoning, that is adding and subtracting, of the consequences of general names agreed upon for the marking and signifying of our thoughts.” (Leviathan, Ch. 5). Hobbes also suggests that reasoning (along with imagining, sensing, and deliberating) can be performed by systems of varying physical types. In his Introduction to Leviathan, he likens a commonwealth to an individual human, saying, “why may we not say that all automata (engines that move themselves by springs and wheels…) have an artificial life? For what is the heart but a spring; and the nerves but so many strings, and the joints but so many wheels…”. The idea that thinking is rule-governed computation that can be carried out by creatures of varying physical types didn’t become common until the middle of the 20th century.
2.2 How Do Thinking Machines And The “Turing Test” Relate?
A.M. Turing (1950) proposed that the question, “Can machines think?” be replaced by, “Is it theoretically possible for a finite state digital computer, provided with a large but finite table of instructions, or program, to provide responses to questions that would fool an unknowing interrogator into thinking it is a human being?” This question is often expressed as “Is it theoretically possible for a Turing machine (appropriately programmed) to pass the Turing Test?”
Turing argues that this question is a legitimate replacement for the original and speculates that its answer is “yes.” Turing identifies thoughts with states of a system defined by their roles in producing internal states and verbal outputs, given verbal inputs. Like Hobbes’s and subsequent functionalist theories, this view states that many physically different systems could have internal states that play these roles. Turing’s work was explicitly invoked by theorists during the beginning stages of 20th-century functionalism and was the inspiration for the “machine state” theories most firmly associated with Hilary Putnam (1960, 1967), which had an important role in the early development of the doctrine.
2.3 What Is Behaviorism?
Behaviorist theories that emerged in the early-to-mid twentieth century are other recent backgrounds of functionalism. These theories include the “logical” or “analytical” behaviorism of philosophers such as Malcolm (1968) and Ryle (1949) and the empirical psychological theories associated with Watson and Skinner.
Logical behaviorism is a thesis about the meanings of our mental state terms or concepts. It states that all statements about mental states and processes are equivalent in meaning to statements about behavioral dispositions. For example, “Henry has a toothache” would mean “Henry is disposed (all things being equal) to cry out or moan and to rub his jaw,” and “Amelia is thirsty” would mean “If Amelia is offered some water, she will be disposed (all things being equal) to drink it.” These statements avoid reference to the organism’s internal states and thus do not denote properties or processes directly observable only by introspection. Logical behaviorists argued that if statements about mental states were equivalent in meaning to statements about behavioral dispositions, there could be an account of how mental state terms could be applied to oneself and others and how they could be taught and learned.
Scientific behaviorism is an empirical theory that attempts to explain the behavior of humans and other animals by appealing to behavioral dispositions. Organisms have lawlike tendencies to behave in certain ways, given certain environmental stimulations. Stimulations and behavior are objectively observable and are part of the natural world. Thus, behavioral dispositions seemed fit to figure centrally in the emerging science of psychology, allowing for a science of human behavior as objective and explanatory as other “higher-level” sciences such as chemistry and biology. Behaviorist theories promised to avoid a regress threatening psychological explanations invoking internal representations. The explanation of behaviors need not appeal to an internal intelligent agent (a “homunculus”) who interprets the representations.
However, both varieties of behaviorism faced a common problem. Logical behaviorism provides an implausible account of the meanings of our mental state terms because a subject can have the mental states without the relevant behavioral dispositions (Chisholm 1957; Geach 1957). For example, Gene may believe that it’s going to rain even if he’s not disposed to wear a raincoat and take an umbrella when leaving the house if Gene enjoys singing in the rain. Subjects can suppress their tendencies to pain behavior even in excruciating pain, while skilled actors can perfect the disposition to produce pain behavior under certain conditions, even if they don’t feel pain (Putnam 1965). The problem is that no mental state, by itself, can give rise to any particular behavior unless one assumes that the subject possesses additional mental states. One cannot give meaning-preserving translations of statements invoking pains, beliefs, and desires in purely behavioristic terms.
Scientific behaviorism faced similar challenges. The theories of Watson, Skinner, et al had some early successes, especially in animal learning, and its principles are still used in various areas of psychology. However, the successes of behaviorism seem to depend upon the experimenters’ implicit control of variables that involve ineliminable reference to organisms’ other mental states (Chomsky 1959). For example, rats are placed into an experimental situation at a certain fraction of their normal body weight, and thus can be assumed to feel hunger and to want food rewards. Similarly, humans in analogous experimental situations want to cooperate with the experimenters, and understand and know how to follow the instructions. Theories that explicitly appeal to an organism’s beliefs, desires, and other mental states, as well as stimulations and behavior, would provide a fuller and more accurate account of why organisms behave as they do. Without compromising the objectivity of psychology, the mental states can be introduced as states that together play a role in the production of behavior, rather than states identifiable solely by introspection. Work began on a range of “cognitive” psychological theories which reflected these presumptions, and “psychofunctionalism” (Fodor 1968, Block and Fodor 1972) is a philosophical endorsement of these new cognitive theories of mind.
3. What Are The Varieties of Functionalism?
Functionalist theories can be thought of as belonging to one of three major types: “machine state functionalism”, “analytic functionalism”, and “psychofunctionalism.” These emerged from early AI theories, empirical behaviorism, and logical behaviorism. However, there is overlap in the bloodlines of these different types, and there are earlier and more recent functionalist theories that fall somewhere in between. For example, Wilfrid Sellars’s (1956) account of mental states as “theoretical entities” is regarded as an early version of functionalism. It takes the characterization of thoughts and experiences to depend partially on their role in providing a scientific explanation of behavior and partially on the logic of the concepts. The three major types of the doctrine are treated separately below.
3.1 What Is Machine State Functionalism?
The early functionalist theories of Putnam (1960, 1967) respond to the difficulties facing behaviorism as a scientific psychological theory and endorse the computational theories of mind that were becoming rivals to it.
Machine state functionalism states that any creature with a mind can be regarded as a Turing machine, whose operation can be fully specified by a set of instructions (a “machine table” or program) having the form:
If the machine is in state Si, and receives input Ij, it will go into state Sk and produce output Ol (for a finite number of states, inputs, and outputs).
This describes the operation of a deterministic automaton, but most machine state functionalists (e.g. Putnam 1967) take the mind to be a probabilistic automaton. In that case, the program specifies, for each state and set of inputs, the probability with which the machine will enter some subsequent state and produce some particular output.
On either model, the mental states of a creature are identified with “machine table states” (S1,…,Sn). These states are not mere behavioral dispositions because they are specified in terms of their relations to inputs and outputs and the state of the machine. For example, believing it will rain is not a disposition to take one’s umbrella after looking at the weather report, but a disposition to take one’s umbrella if one looks at the weather report and wants to stay dry. Machine state functionalism can avoid difficulties for behaviorism. These machines model how internal states whose effects on output occur by means of mechanical processes can be viewed as representations. Machine table states are not tied to any physical realization, as the same program can be run on different computer hardware.
Turing machines provided a model for early functionalist theories. The idea that mental states are computational states appears in many theories of the mind (Rey 1997). Because machine table states are total states of a system, contemporary functionalists have adopted another way of characterizing mental states: as states implicitly defined by the Ramsey-sentence of a psychological theory (common sense, scientific, or something in between).
3.2 How Are Functional Definitions And Ramsey-Sentences Used?
This method, presented by David Lewis (1972), building on a technique introduced by Frank Ramsey, treats mental state terms as defined by the Ramsey sentence of one or another psychological theory (common sense, scientific, or something in between). Analogous steps can be taken to produce the Ramsey-sentence of any theory. For example, consider the generalizations about pain: pain tends to be caused by bodily injury; pain tends to produce the belief that something is wrong with the body and the desire to be out of that state; pain tends to produce anxiety; pain tends to produce wincing or moaning.
To construct the Ramsey-sentence of this “theory”, the first step is to conjoin these generalizations, then replace names of mental states with variables, and then quantify those variables:
∃x∃y∃z∃w(x tends to be caused by bodily injury & x tends to produce states y, z, and w & x tends to produce wincing or moaning).
This includes only quantifiers that range over mental states, terms that denote stimulations and behavior, and terms that specify causal relations. It provides implicit definitions of the mental state terms of the theory. An individual will have those mental states if it possesses a family of first-order states that interact as specified by the theory. Functionalists acknowledge that the first-order states that satisfy the functional definitions may vary from species to species, but they specify that, for each individual, the functional definitions be uniquely satisfied.
The Ramsey sentence of a psychological theory defines a system’s mental states “all at once” as states that interact with stimulations to produce behavior (Lewis 1972). The differences between analytic and psychofunctionalism are differences in the Ramsey-sentences of our “commonsense theory of the mind” versus our empirical psychological theories of the roles of mental states in the production of other mental states and behavior.
3.3 What Is Analytic Functionalism?
Like logical behaviorism, the goal of analytic functionalism is to provide dispositional translations of our ordinary mental state terms or concepts. Analytic functionalism permits reference to causal and transitional relations that a mental state has to stimulations, behavior, and other mental states. So, for example, “Blanca wants some coffee” need not be rendered in terms such as “Blanca is disposed to order coffee when it is offered”, but rather as “Blanca is disposed to order coffee when it is offered, if she has no stronger desire to avoid coffee”. Any theory acceptable to analytic functionalists must include generalizations about mental states, their environmental causes, and their joint effects on behavior. These generalizations are known and “platitudinous” to analyze our ordinary concepts of mental states (Smart 1959, Armstrong 1968, Shoemaker 1984a,b,c, Lewis 1972, Braddon-Mitchell, and Jackson 1996/2007).
A major question is whether a theory that limits itself to “platitudes” about the causal relations between stimulations, mental states, and behavior can make the right distinctions among mental states. It may be so “liberal” that it can be realized by systems without mentality, such as the economy of Bolivia (Block, 1980b). However, commonsense psychology has more resources than it may seem. First, it need not be restricted to platitudes that can be accessed immediately. It may take Socratic questioning to prompt us to recognize similarities and differences among the causal-relational properties of our mental states. The information accessed by questioning was always available to us, and so can count as the deliverances of common sense, rather than empirical investigation. Moreover, commonsense psychology is not stagnant. Over time, it can absorb information acquired by exposure to empirical theories while retaining its platitudinous status.
Many functionalists argue that commonsense theories do not have enough resources to capture the causal roles of the internal states that differentiate us from other cognitive systems. They look to psychofunctionalism, which derives from reflection upon the goals and methodology of the “cognitive” psychological theories that are the descendants of scientific behaviorism.
3.4 What Is Psychofunctionalism?
In contrast to the scientific behaviorists’ insistence that the laws of psychology appeal only to behavioral dispositions, cognitive psychologists argue that the best empirical theories of behavior take it to be the result of mental states and processes, introduced in terms of the roles they play in producing the behavior to be explained. For example, a psychologist may begin to construct a theory of memory by postulating the existence of “memory trace” decay, a process whose occurrence or absence is responsible for effects such as memory loss and retention and which is affected by stress or emotion in certain ways (Fodor’s 1968, Ch. 3).
On a theory of this sort, what makes some neural process an instance of memory trace decay is a matter of how it functions, or the role it plays, in a cognitive system. Its neural or chemical properties are relevant only insofar as they enable that process to do what trace decay is hypothesized to do. The same is true for all mental states and processes invoked by cognitive psychological theories. Cognitive psychology is intended to be a “higher-level” science like biology, and thus to have autonomy from lower-level sciences such as neurophysiology. In biology, physically disparate entities can all be hearts as long as they function to circulate blood. Similarly, disparate physical structures or processes can be instances of memory trace decay (or thoughts, sensations, and desires) if they play the roles described by the relevant cognitive theory.
Psychofunctionalism adopts the methodology of cognitive psychology in its characterization of mental states and processes as entities defined by their role in a cognitive psychological theory. What distinguishes it from analytic functionalism is that the information used in the functional characterization of mental states and processes needn’t be restricted to common knowledge, but can include information available only by careful empirical observation and experimentation. For example, a psychofunctional theory might distinguish depression from sadness or listlessness even though the causes and effects of these syndromes are difficult to untangle by consulting intuitions. Psychofunctional theories will not include characterizations of mental states for which there is no scientific evidence, such as buyer’s regret or hysteria, even if common sense affirms them.
Psychofunctional theories can avail themselves of all the tools of inquiry available to scientific psychology and will make the distinctions that are scientifically sound. However, psychofunctionalism is open to the charge that it may be overly “chauvinistic” (Block 1980b), because creatures whose internal states share the rough, but not fine-grained, causal patterns of ours wouldn’t count as sharing our mental states. Many psychofunctionalists may not regard this as an unhappy consequence and argue that it’s appropriate to treat only those who are psychologically similar as having the same mental states.
If the laws of the best empirical psychological theories diverge from our “folk psychology”, it will be hard to take psychofunctional theories as providing an account of our mental states (Loar 1981, Stich 1983, Greenwood 1991, Braddon-Mitchell, and Jackson 1996/2007). However, theorists (Horgan and Woodward 1985) argue that it’s likely that future psychological theories will be close to “folk psychology”, though this has been debated (Churchland 1981).
Early in the Psycho-Physical Identity Theory, the thesis that each mental state can be identified with some brain state or neural activity, early identity theorists (e.g. Smart 1959) argued that it makes sense to identify pain with C-fiber stimulation. The terms ‘pain’ and ‘C-fiber stimulation’ do not have the same meaning, but they can denote the same state. An identity statement is not a priori. Just because I need not consult some sort of brain scanner when reporting that I’m in pain doesn’t mean that the pain I report is not a neural state that a brain scanner could detect.
Max Black (Smart 1959) argued that the only way terms with different meanings can denote the same state is to express different properties of that state. If terms like ‘pain’, ‘thought’ and ‘desire’ are not equivalent in meaning to physicalistic descriptions, they can denote physical states only by expressing irreducibly mental properties of them. This is the “Distinct Property Argument,” and it undermined a thorough-going materialistic theory of the mind.
In response, Smart (1959) and later, Armstrong (1968) countered that there could be relational, “topic-neutral” terms that are equivalent in meaning to terms such as ‘pain’, ‘thought’, and ‘desire’. These terms are not irreducibly mental. The appeal of meaning-preserving functional characterizations derives from their promise to provide more plausible topic-neutral equivalents of our mental state terms and blunt the anti-materialistic force of the Distinct Property Argument (Lewis 1966).
However, there is a dispute about whether any relational characterizations of our mental states, especially sensations, could fully preserve the meanings of our mental state terms. There is also a dispute about how seriously to take the Distinct Property objection.
There is another distinction between kinds of functional theory, known as “role” functionalism and “realizer” (or “filler”) functionalism (McLaughlin 2006).
3.5 What Is The Difference Between Role-Functionalism and Realizer-Functionalism?
Consider the functional theory of pain introduced in the first section:
Pain is the state that tends to be caused by bodily injury, to produce the belief that something is wrong with the body and the desire to be out of that state, to produce anxiety, and, in the absence of any stronger, conflicting desires, to cause wincing or moaning.
If this functional role is played by C-fiber stimulation in humans, then humans can be in pain simply by undergoing C-fiber stimulation. What is the property of pain itself? Is it the relational property of being in some state or other that plays the “pain role” or the C-fiber stimulation that plays this role?
Role functionalists identify pain with that relational property. Realizer functionalists take a functional theory to provide descriptions of whichever properties satisfy the functional characterizations. If the property that occupies the causal role of pain in human beings is C-fiber stimulation, then pain in humans would be C-fiber stimulation.
Some of the earliest versions of analytic functionalism (Lewis 1966, Armstrong 1968) were presented as functional specification theories that could pave the way for a psycho-physical identity theory by defusing the Distinct Property Argument. However, if there are differences in the physical states that satisfy the functional definitions in different creatures, such theories would violate a key motivation for functionalism: that creatures with states that play the same role in the production of other mental states and behavior possess the same mental states.
There may be physical similarities between the neural states of creatures that satisfy a given functional characterization. Even if this is so, it is unlikely that these similarities hold of all the creatures who could share our functional organization, and thus our theory of mental states would remain overly “chauvinistic” (Block’s 1980). One could counter the charge of chauvinism by suggesting that all creatures with states that satisfy a given functional characterization possess a common disjunctive state or property. Or one could suggest that, even if all creatures possessing states that occupy the pain role are not in the same mental state, they share a closely related higher-level property. However, neither alternative goes far enough to preserve the functionalist intuition that functional commonality outweighs physical diversity in determining whether creatures can possess the same mental states. Thus many functionalists advocate role functionalism, which permits mental state terms to be rigid designators (Kripke 1972), denoting the same items in all possible worlds.
Some functionalists consider realizer functionalism to be in a better position than role functionalism to explain the causal efficacy of the mental. If I stub my toe and wince, my toe stubbing causes my pain, which causes my wincing. If pain is realized in me by some neural event-type, then insofar as there are generalizations linking events of that type with wincings, one can give a complete causal explanation of my wincing by citing the occurrence of that neural event. And thus it seems that the higher-level role properties of that event are causally irrelevant. This is known as the “causal exclusion problem”, which arises for functional role properties, and for any sort of mental states or properties not type-identical to those invoked in physical laws.
4. How Do Plausible Functional Theories Work?
Providing functional characterizations of individual mental states has been vague, and the examples simplistic. Can we improve these and determine which version of functionalism is likely to be successful? Experiential states, such as perceptual experiences and bodily sensations, have qualitative character, and intentional states, such as thoughts, beliefs, and desires, represent the world. Experiential states have representational contents, and intentional states have qualitative character. Nonetheless, they are discussed separately to focus on the features of each.
4.1 What Characterizes Experiential States?
The common strategy in the most successful treatments of perceptual experiences and bodily sensations is to individuate experiences of general types in part by appealing to their positions in the “quality spaces” associated with the relevant sense modalities. So, for example, the experience of a reddish-orange could be partially characterized as the state produced by viewing a color swatch, which tends to produce the judgment that the state is more similar to the experience of red than of orange. Judgments will be characterized in terms of their tendencies to produce sorting or categorization behavior.
This strategy may seem fatal to analytic functionalism, which restricts itself to a priori information to distinguish among mental states, because it’s not clear that the information needed to distinguish experiences such as color perceptions is available to commonsense. However, if sensations and perceptual experiences are characterized in terms of their places in a “quality space” determined by a person’s judgments of similarity and dissimilarity (and also in terms of their tendencies to produce emotional effects), then these characterizations may qualify as platitudinous.
There are limits to this strategy (see Section 5.5.1 on the “inverted spectrum” problem), which seem to leave two options for analytic functionalists: deny that the distinctions that the critics suggest exist, or embrace another version of functionalism in which the characterizations of mental states can provide information rich enough to individuate the states in question.
There has been skepticism about whether any functionalist theory can capture the qualitative character of experiential states such as color perceptions, pains, and other bodily sensations.
4.2 How Do You Characterize Intentional States?
Intentional states such as beliefs, thoughts, and desires (sometimes called “propositional attitudes”) have been thought to be easier to characterize functionally than experiential states (but not always). We can characterize beliefs as states produced by sense-perception or inference from other beliefs, and desires as states with causal relations to the system’s goals and needs. We can specify how beliefs and desires tend to interact with one another and other mental states to produce behavior.
This characterization needs more detail. There are questions about characterizing intentional states, particularly belief. One is whether a subject should be regarded as believing that p if there is a mismatch between her avowals that p and the behaviors associated with believing that p in standard circumstances. Another question is whether the states that interact with desires to produce behavior are best regarded as “full on” beliefs, or rather as representations of the world for which individuals have varying degrees of confidence. Functionalism can accommodate different answers to these questions.
Functionalists need to say more about what makes a state a particular belief or desire, for example, the belief that it will snow tomorrow. Most functional theories describe such states as relations toward the same state of affairs or proposition. Differences in the contents of intentional states can be similarities in the propositions to which these states are related. But what makes a mental state a relation to some proposition P? And can these relations be captured by the functional roles of the states?
The development of conceptual role semantics may answer these questions. For Julian to believe that P is for Julian to be in a state that has causal relations to other beliefs and desires that mirror inferential relations among propositions. This raises questions about whether states capable of entering into such interrelations can be construed as being or including elements of a “language of thought”. Also, whether differences in the inclinations of different individuals make for differences in their intentional states.
A challenge for functionalism are intuitions that support “externalism”, the thesis that what mental states represent cannot be characterized without appealing to features of the environments in which those individuals are embedded. Thus, if one individual’s environment differs from another’s, they may count as having different intentional states, even though they reason the same ways and have the same take on those environments.
The “Twin Earth” scenarios introduced by Putnam (1975) support an externalist individuation of beliefs about natural kinds such as water, gold, or tigers. Twin Earth is a planet on which things look, taste, smell, and feel the way they do on Earth, but which have different microscopic structures. The stuff that fills the streams and comes out of the faucets, though it looks and tastes like water, has molecular structure XYZ rather than H2O. We mean something different by our term ‘water’ than our Twin Earth counterparts mean by theirs, and beliefs we describe as beliefs about water are different from those that our Twin Earth counterparts would describe. Conclusions can be drawn for all cases of belief regarding natural kinds.
The same problem arises for other beliefs as well. Tyler Burge (1979) presents cases in which a person, Oscar, and his counterpart have different beliefs about syndromes and artifacts because the usage of these terms by their linguistic communities differ. In Oscar’s community, the term ‘arthritis’ is used as we use it, whereas in his counterpart’s community ‘arthritis’ denotes inflammation of the joints and various maladies of the thigh. Even if Oscar and his counterpart complain about the ‘arthritis’ in their thighs and make the same inferences involving ‘arthritis’, they mean different things by their terms and must be regarded as having different beliefs. If these cases are convincing, then there are differences among intentional states that can only be captured by reference to the practices of an individual’s linguistic community. These cases suggest that if functionalist theories cannot refer to an individual’s environment, then capturing the content of intentional states is beyond the scope of functionalism.
Externalist individuation of intentional states may fail to capture commonalities between ourselves and our counterparts that are relevant to the explanation of behavior. If my Twin Earth counterpart and I have come in from a long hike, declare that we’re thirsty, say “I want some water” and head to the kitchen, it seems that our behavior can be explained by citing a common desire and belief. Functional theories should capture the “narrow content” of beliefs and desires: representational features individuals share with their Twin Earth counterparts. There is no consensus about how functionalist theories should treat these features, and some philosophers have expressed skepticism about whether such features should be construed as representations. If a generally acceptable account of narrow content can be developed, if the intuitions inspired by “Twin Earth” scenarios remain stable, then the content of intentional states cannot be captured by functional characterizations alone.
4.3 How Are the Inputs And Outputs of a System Characterized?
Considerations about whether certain beliefs are to be externally individuated raise the question about how to characterize the stimulations and behaviors that serve as inputs and outputs to a system. Should they be construed as events involving objects in a system’s environment, or rather as events in that system’s sensory and motor systems? Theories of the first type are “long-arm” functional theories (Block 1990), since they characterize inputs and outputs by reaching out into the world. Adopting a “long-arm” theory would prevent our Twin Earth counterparts from sharing our beliefs and desires and honor intuitions that support an externalist individuation of intentional states.
If functional characterizations of intentional states are intended to capture their “narrow contents”, then the inputs and outputs of the system will have to be specified in a way that permits individuals in different environments to be in the same intentional state. Inputs and outputs may be characterized as activity in specific sensory receptors and motor neurons. This option restricts the range of individuals that can share our beliefs and desires, because creatures with different neural structures will be prevented from sharing our mental states, even if they share all our behavioral dispositions. This option would not be open to analytic functionalist theories, because generalizations that link mental states to neurally specified inputs and outputs would not have the status of platitudes.
Sensory stimulations abstract from the specifics of human neural structure to include any possible creature that seems to share our mental states, but is concrete enough to rule out entities that are not cognitive systems (such as the economy of Bolivia). If there is no such formulation, then functionalists will have to dispel intuitions that certain systems can’t have beliefs and desires or concede that their theories may be more “chauvinistic” than hoped.
The issues here mirror the issues regarding the individuation of intentional states. More work is needed to develop the “long-arm” and “short-arm” alternatives and to assess their merits and deficiencies.
5. What Are The Objections To Functionalism?
There have been many objections to functionalism that apply to all versions of the theory. Some have already been introduced, but they will be addressed here in more detail.
5.1 How Do Functionalism and Holism Relate?
One difficulty for every version of the theory is that functional characterization is holistic. Functionalists hold that mental states are to be characterized in terms of their roles in a psychological theory. However, such theories incorporate information about a variety of mental states. Thus, if pain is interdefined with articulated beliefs and desires, then animals who don’t have internal states that play the roles of our beliefs and desires can’t share our pains. Differences in the ways people reason might make it impossible for them to share the same mental states.
If a creature has states that approximately realize our functional theories or realize some more specific defining subset of the theory, then they can qualify as mental states of the same types as our own. The problem is to specify what it is to be an approximate realization of a theory or what a “defining” subset of a theory is intended to include.
5.2 How Do Functionalism and Mental Causation Relate?
The “causal exclusion problem” is another concern: whether role functionalism can account for the causal efficacy of our mental states. If pain is realized in me by some neural state-type, then insofar as there are physical generalizations linking states of that type with pain behavior, one can give a complete causal explanation of my behavior by citing the occurrence of that neural state. And thus, the higher-level role properties of that state are causally irrelevant.
Some suggest that it arises from an overly restrictive account of causation. Instead, causation should be regarded as a counterfactual dependence between states of certain types, or as a regularity that holds between them. If this is correct, then functional role properties could count as causally efficacious. However, the plausibility of these accounts of causation depends on their prospects for distinguishing causal relations from those that are clearly epiphenomenal, and some have expressed skepticism about whether they can do the job.
Causation is best regarded as a relation between types of events that must be invoked to provide general explanations of behavior. Though many maintain that there is a difference between generalizations that are causal and those that contribute to our understanding of the world, theorists charge that this objection depends on a restrictive view of causation that would rule out too much.
Mental and physical causes would overdetermine their effects, since each would be causally sufficient for their production. And, though some theorists argue that overdetermination is widespread, others contend that there is a relation between role and realizer that provides an explanation of how both can be causally efficacious without overdetermining causes. For example, Yablo suggests that mental and physical properties stand in the relation of determinable and determinate, and argues that our conviction that a cause should be commensurate with its effects permits us to take the determinable property to count as causally efficacious in psychological explanation. Bennett suggests that the realizer properties metaphysically necessitate the role properties in a way that prevents them from satisfying the conditions for overdetermination.
There has been substantial recent work on the causal exclusion problem, which arises for any non-reductive theory of mental states. But there is a worry about causation that arises for role-functionalism and other dispositional theories, the problem of “metaphysically necessitated effects” (Rupert 2006, Bennett 2007). If pain is defined as the state of being in some state that causes wincing, then it seems that the generalization that
