Dualism vs. Materialism: A Response to Paul Churchland
by M. D. Robertson
from http://www.hu.mtu.edu/~mdrobert/churchl.pdf, archived at www.newdualism.org/papers/M.Robertson/churchl.htm
Paul M. Churchland, in his book, Matter and Consciousness, provides a survey of the issues and positions associated with the mind-body problem. This problem has many facets, and Churchland addresses several of them, including the metaphysical, epistemological, semantic, and methodological aspects of the debate. Churchland, of course, has very strong views on the subject, and does not hide his biases on the matter.
In this paper I shall reexamine the metaphysical aspect of the mind-body problem. The metaphysical question concerns the existential status of the mind and the body, and the nature of the relationship between them. Like Churchland, I shall not hide my biases on the matter. What follows may be thought of as a rewriting of the second chapter of Churchland's book ("The Ontological Issue") from a non-naturalistic perspective.
René Descartes argued that the defining characteristic of minds was cogitation in a broad sense, while that of bodies was spatial extension. Descartes also claimed that minds were not spatially extended, nor did bodies as such think. Thus minds and bodies were separate substances. This view has come to be called substance dualism. Descartes's argument for substance dualism can be summarized as follows:
- Minds exist.
- Bodies exist.
- The defining feature of minds is cogitation.
- The defining feature of bodies is extension.
- That which cogitates is not extended.
- That which is extended does not cogitate.
- Minds are not bodies, and bodies are not minds. That is to say, there are at least two distinct kinds of existents: minds and bodies. The mental and the material are completely different substances.
Descartes's contemporaries and successors have raised a number of objections to this view. Among his contemporaries, the problem of how these two completely distinct substances could interact causally, as they apparently do, loomed the largest. Although the notion that distinct substances cannot interact is simply an a priori assumption, many philosophers have found it intuitively compelling.
In response to this problem, philosophers have argued that one or the other of Descartes's substances must not exist, and that a single substance must instantiate both minds and bodies, assuming that both minds and bodies exist in the first place; considerations of parsimony lend further support to this approach. This entails the rejection of one or more premises of the above position. Idealists such as George Berkeley have denied (2), thereby denying the existence of bodies or matter, while materialists have denied (5), (6), and/or (1), thereby asserting either that minds are material or that minds do not exist at all.
I shall not address idealism in this essay. For various reasons that are outside the scope of this discussion, materialism has the greatest following among contemporary philosophers. But philosophers have not been able to agree on a formulation of the materialist position. In this essay, I shall examine five forms of materialism: identity theory, philosophical behaviorism, eliminativism, property dualism, and functionalism.
Paul Churchland suggests four advantages that materialism has over dualism, but these advantages are dubious.
Firstly, as noted, materialism is more parsimonious; but until materialists prove that materialism can explain everything that substance dualism can explain, there is no reason to give parsimony any weight.
Secondly, Churchland claims that materialism can in fact explain things that dualism cannot, and cites various advances in neuroscience in understanding the function of the brain, and the corresponding lack of understanding of the proposed mental substance. Churchland also notes the obvious dualist response: progress in understanding material substance is irrelevant to the question of whether material substance is all there is. Churchland counters that what the dualist takes to be "the central capacities of the nonphysical mind, capacities such as reason, emotion, and consciousness itself" have in fact been elucidated by "materialist research programs":
So far as the capacity for reasoning is concerned, machines already exist that execute in minutes sophisticated deductive and mathematical calculations that would take a human a lifetime to execute. And so far as the other two mental capacities are concerned, studies . . . have revealed many interesting and puzzling facts about the neurochemical and neurodynamical basis of both emotion and consciousness. The central capacities, no less than the peripheral, have been addressed with profit by various materialist research programs. (20)
But this response reveals a deep confusion about the nature of consciousness, on the part of both the dualist and the materialist. Churchland's remarks show a failure to distinguish between consciousness and mere information processing. But evidence from the neurosciences may show that the dualist has also failed to draw some important distinctions. The dualist lumps emotions, reasoning, consciousness, and volition under the same general category--according to Descartes, they are all simply forms of cogitation. This failure to recognize important generic differences between these phenomena makes the dualist position vulnerable to certain materialist objections (I shall explore these differences in greater detail later).
This vulnerability manifests itself in Churchland's third argument against substance dualism, which he calls "the argument from the neural dependence of all known mental phenomena" (20). Churchland is here referring to the effects of drugs and brain damage on reasoning, the emotions, and consciousness. But the dualist can accept the premise of this argument while denying the conclusion. As noted, the claim that two distinct substances cannot affect each other causally is one that the dualist need not accept. The dualist can accept the claim that physical events affect mental phenomena, and reply that mental events (especially volitions) have physical effects. But dualists would be in an intuitively stronger position if they would make the aforementioned distinctions, for volitions are not clearly dependent on neural processes, nor is it clear in what sense consciousness, properly understood, is dependent in this way.
Churchland's last argument is the argument from evolutionary history.
For purposes of our discussion, the important point about the standard evolutionary story is that the human species is a wholly physical outcome of a purely physical process . . . we are notable only in that our nervous system is more complex and powerful than those of our fellow creatures. . . . (21)
Churchland is simply wrong about the import of evolutionary history. Evolutionary theory as it is currently formulated is a diachronic study of material processes. But like the synchronic studies of material processes discussed in Churchland's second argument, above, no amount of explanatory success along these lines has any relevance to the question of whether such material processes are all there is.
The strongest arguments for substance dualism over materialism stems from introspective evidence. Introspection reveals qualia and self-awareness. Materialists have thus far been unable to provide a satisfactory account of "inner" experience, insofar as neither that which introspects nor that which is introspected admits of materialist explanation. Regardless of how much credence introspective evidence merits for scientific purposes, the very fact that introspection occurs at all is a blow to the materialist position. Materialists have thus far failed to provide an account of how qualia or self-awareness could have a material basis. These failures will be examined in greater detail below.
Varieties of Materialism
Materialism can be grouped into two broad categories. Those of the first group, which I shall label non-emergentist materialism, assert that the mind either is reducible to recognizably nonmental structures and processes (such as those studied by biologists or physicists), or that the mind does not exist at all. Those of the second group, which I shall label emergentist materialism, assert that the mind is an irreducible existent in some sense, albeit not in the sense of being an ontological simple, and that the study of mental phenomena is independent of other sciences. The first group includes identity theory, philosophical behaviorism and eliminativism; the second group includes property dualism and functionalism.
Identity theory asserts that mental states "just are" physical states, specifically states of the brain and central nervous system, in exactly the same way that water "just is" H2O. Identity theorists predict that a sufficiently well-developed neuroscience will someday be able to provide one-to-one correspondences between common-sense mentalistic descriptions of moods, thoughts, etc. and states of the central nervous system. Identity theorists make the further claim that such correspondences will not merely indicate the lawful covariance of two separate processes, but will rather be evidence of the type-identity of these processes.
Identity theory allows the use of ordinary mentalistic discourse, while at the same time placing mental phenomena on a material basis, without introducing any additional ontological apparatus. But despite its affirmation of the meaningfulness of talk about inner states, identity theory fails to deal with the introspection issue.
Identity theorists have been accused of committing a "category error" in that the properties that apply to mental phenomena do not apply to material phenomena and vice versa. Thoughts do not have a spatial location, and brain states do not have qualia, and it seems logically possible that mental states could exist in the absence of brain states and vice versa. Churchland suggests that the identity theorists might respond that this is merely a semantic problem, one that can be overcome if we train ourselves to apply brain-state predicates to mental states, in the way that we have learned to talk about temperature in terms of mean kinetic energy.
The following thought-experiment may suggest why such a response is unsatisfactory. Suppose that the occurrence of a certain abdominal pain is invariably and exactly correlated with the occurrence of a certain brain state. The dualist, of course, asserts the correlation is just that--a correlation and nothing more, and just as the correlation between the position of a needle on a fuel gauge and the level of gasoline in the tank does not imply the identity of these phenomena, neither is identity implied in the case of the pain. The identity theorist, however, asserts such an identity. But now suppose that both the pain and the brain state are also correlated with a certain state of the stomach, e.g., the flaring of an ulcer. Now our original identity theorist is joined by three more identity theorists: identity theorist #2 asserts the identity of the mental state and the stomach state, identity theorist #3 asserts the identity of the stomach state and the brain state, and identity theorist #4 asserts the identity of all three states. I leave it to the reader to draw the implications.
One further objection to the identity theory runs along these lines: it seems that is is possible for a deaf person to know everything science could tell us about acoustics, the physiology of the ear, music theory, etc., yet still not know what it is like to hear Beethoven's ninth symphony. After all the physical phenomena are completely understood, still, something remains.
To this objection Churchland responds,
The identity theorist can admit a duality, or even a plurality, of different types of knowledge without thereby committing himself to a duality in types of things known. The difference between a person who knows all about the visual cortex but has never enjoyed the sensation-of-red, and a person who knows no neuroscience but knows well the sensation-of-red, may reside not in what is respectively known by each (brain states by the former, nonphysical qualia by the latter) but rather in the different type, or medium, or level of representation each has of the same thing: brain states. (34)
But in bringing in representation, Churchland cuts his own throat. For if sensation-of-red is a representation of a brain state, then the question becomes, why does such a representation have the experiential quality that it does, or indeed any experiential quality at all? Qualia may constitute representational knowledge of brain states, but representations themselves can be objects of knowledge and description, especially when statements about what they represent do not exhaust all that can be known about them, as is the case with qualia. In addition to the monadic properties of qualia, if qualia are representations of brain states then a further question arises, viz., to what or whom are these brain states represented, which brings self-awareness back into the picture. The questions raised by representation are ones for which the dualist has a ready answer, but not the materialist.
Philosophical behaviorism makes a weaker reduction claim than identity theory does. Philosophical behaviorists cash out their reduction claims in terms of synonymy, rather than identity. According to philosophical behaviorism, talk about minds is synonymous with talk about behavioral dispositions. The model for such a reduction is based the verificationist/operationalist approach to dispositional terms, whereby dispositions are defined in terms of counterfactuals, e.g., "fragile" is defined as "would break if dropped on a hard surface from a height of two feet, etc.". Following such a model, the philosophical behaviorist tries to define mentalistic predicates like "is angry" or "believes in ghosts" or "wants a new car" in terms of counterfactuals about the the subject's observable behavior.
This position does not address the introspective issue at all. Setting aside the usual problems that have largely discredited verificationalist semantic theories, philosophical behaviorism's definition of mental states in terms of publicly observable behaviors simply ignores the issues of whether and how there can be phenomena that are not publicly observable--which is what self-awareness and qualia purport to be.
In any case, specifying the relevant counterfactuals is hard enough for simple physical properties like fragility; it becomes a practical impossibility for many mental terms, as Churchland acknowledges (24).
Eliminativism takes a more radical stance than identity theory or philosophical behaviorism. Eliminativism denies that mental predicates can be reduced to physical predicates, on the grounds that talk of minds and mental properties is incoherent and ultimately does not refer to anything, as is the case with talk of phlogiston and witches. Belief, desire, fear, sensation, pain, joy, etc., are elements of a conceptual framework ("folk psychology") that does such a poor job of representing the phenomena to which it is applied ("conscious intelligence") that it should be discarded.
Eliminativism is Churchland's preferred theory. He offers three arguments in its favor.
Firstly, there is the argument from explanatory poverty. Churchland cites sleep, learning, memory, and mental illness as phenomena that folk psychology either misunderstands or does not explain at all, even unsuccessfully. According to Churchland, the explanatory and descriptive resources of folk psychology are particularly inadequate when applied to people with damaged brains (46).
Secondly, there is the argument from induction. Our folk theories about fire, astronomy, and motion were highly erroneous and had to be discarded. Conscious intelligence is much more complicated than these other phenomena. So it seems extremely unlikely that folk psychology should be any more accurate than the other folk theories mentioned.
Thirdly, there is the argument from a priori probability of eliminativism compared to other sorts of materialism. Comparing eliminativism to identity theory and functionalism, Churchland notes that the identity theorist expects to find "vindicating matchups" of the concepts of folk psychology "in a mature neuroscience" (46) (such matchups would be token identities for functionalism, rather than the type identities of the identity theory). But Churchland notes that there are many ways in which a neuroscience can be explanatorily successful without providing such intertheoretic matchups. So it would seem that eliminativism has a higher probability of being correct.
Regarding the first and second arguments, if Churchland's characterization of folk psychology is correct, then mentalistic predicates are terms in a theory whose function is to explain conscious intelligence. To adequately address this claim would require a long digression into issues that pertain to epistemology and the philosophy of science. I would like to keep focused on the ontological issue as much as possible, so I will merely suggest an alternative characterization and acknowledge that it needs further argument.
The first and second arguments are based on a misconstrual of the nature of the problem. Specifically, Churchland confuses the explanans and the explanandum. Mentalistic predicates are not theoretical terms. Rather, these terms refer to phenomena that are themselves the objects of possible explanation. Churchland's claim is that mentalistic discourse is a theory about conscious intelligence in the way that discourse about Zeus's thunderbolts is a theory about lightning, and that just as discourse about Zeus cannot be reduced to discourse about static electricity, and should simply be discarded as a literal account of what lightning is, so should mentalistic discourse be discarded for analogous reasons. My claim is that mentalistic discourse is like a claim about lightning itself, i.e., it refers to something that can be designated by some sort of ostension.
Presumably Churchland would disagree with Nietzsche's aphorism, "There are no facts, there are only interpretations." Regardless of the lack of a clear dividing line between theory and observation, and regardless of the inseparability of perception and interpretation, one does not beg the question by insisting that there must be something that our theories and interpretations are about. To eliminate the concept of mind is not to do away with a bad explanation; rather, it is to deny that there is anything there to be explained at all.
All the above attempts to reduce or eliminate mental concepts fail because they all try to sweep something under the rug. None of them seriously comes to grips with self-awareness or qualia. At best, non-emergentist materialism provides a consistent picture of a world in which selfawareness and qualia do not exist. Most philosophers and even more non-philosophers find it obvious that these things do exist. This has led materialist philosophers to try to construe the mind as an emergent property. The idea behind emergentist materialism is that organized complexes of matter can have properties that cannot be predicated of the material constituents of such complexes--mental properties being a case in point.
Property Dualism asserts that when matter is organized in the appropriate way (i.e., organized in the way that living human bodies are organized), mental properties emerge. Different versions of property dualism describe this in different ways. Epiphenomenalism and interactionism are two such versions.
Epiphenomenalism asserts that while material causes give rise to sensations, volitions, ideas, etc., such mental phenomena themselves cause nothing further--they are causal dead ends. Thus, our conviction that we have conscious experience is well-founded, but our sense of the connection between our conscious experience and our actions is an illusion.
As materialists, epiphenomenalists are committed to the view that the origin of conscious organisms must be consistent with evolutionary theory, but to achieve this, the epiphenomenalist is forced to use the loopholes in the laws of natural selection. Since, according to epiphenomenalism, consciousness has no effect on activity, and therefore cannot affect survival, epiphenomenalism must claim that consciousness is somehow an unavoidable side effect of an adaptive mutation, or is itself a mutation which has persisted due to a lack of maladaptive consequences.
Epiphenomenalism allows a thoroughly materialist ontology to coexist with self-awareness and qualia, but has little to say about the nature of this coexistence. Epiphenomenalism points to the central nervous system of higher vertebrates and asserts that such a material complex has consciousness, but cannot offer any finer-grained analysis--it cannot tell why this particular material organization is conscious, but rocks, trees, and robots are not.
What little it does say about how self-awareness and qualia depend on matter conflicts with our intuitions about the role the mind plays in our lives. To the extent that epiphenomenailism neither satisfies such intuitions nor explicates the material processes it postulates, epiphenomenalism fails to provide a compelling alternative to substance dualism or non-emergentist materialism.
While epiphenomenalism conflicts with certain intuitions about the mind, interactionism conflicts with intuitions about matter. Interactionism allows mental causes to produce material effects, and vice versa. But having allowed this, interactionism offers no reason why such causes cannot in principle be reduced to material processes that are or someday will be better understood. Interactionism seems to be practically indistinguishable from a pessimistic version of the identity theory, one that claims that mental processes are identical to material processes, but in ways that we cannot understand. Alternatively, the interactionist has the option of asserting that consciousness is a fundamental property of matter, but in that case the practical difference between interactionism and substance dualism becomes unclear--the relationship between mind and matter is equally inexplicable in each case.
Functionalism claims that mental states are functional states. As such, they are individuated in terms of their relationship to environmental inputs, behavioral outputs, and other mental states (unlike behaviorism, which individuates mental states in terms of environmental inputs and behavioral outputs alone). These mental states may be realized by any number of material or even immaterial things--mental states may be thought of as being analogous to chess pieces, whose defining characteristics are specified in terms of the role they play in the game, not in terms of the wood, plastic, or whatever that particular pieces might be made of. Functionalism, which bears a certain resemblance to the medieval theory of hylomorphism, is therefore compatible with substance dualism as well as materialism.
Functionalism has a number of advantages over the materialist theories thus far discussed. It explains how non-human aliens or sufficiently advanced robots might have mental states, in spite of their lack of brains like ours. It explains how mental states emerge from matter in a relatively non-mysterious way. Mental states for the functionalist can be defined in "folk-psychological" terms or in the terms of a more sophisticated psychological theory, so if it turns out that the eliminativists are right about the referential status of ordinary mentalistic discourse, functionalism can accomodate the eliminativists' insight without denying the existence of mental states as an object of theoretical explanation.
But functionalism has a number of shortcomings. Like non-emergentist materialism, functionalism fails to deal with the introspective issue. It seems logically possible that an entity with the same functional organization as humans might not have self-awareness or qualia, and vice versa. And although functionalism identifies mental state tokens with brain-state tokens, unlike the typeidentity claims of identity theory, like the claims of identity theory this claim depends on a substantial quantity of empirical findings which have yet to surface.
Substance Dualism Reexamined
Given the failures of materialist theories to explain how matter could have the properties associated with introspection, substance dualism would seem to have a clear dialectical advantage. But substance dualism as formulated by Descartes fails to make certain important distinctions, and because of this vagueness, Cartesian dualism seems to classify as mental certain processes that are more properly classified as functional or even material. Since materialists can explain these putatively mental processes in material terms, it might be supposed that other mental properties might be explained materialistically also. If the mental is delineated more precisely, these errors can be avoided.
For Descartes, the self is a mind, and a mind is essentially a "thinking thing" (res cogitans). But Descartes uses the term "thinking" very loosely, including reasoning, imagination, emotion, sensation, consciousness, self-awareness and volition under that rubric. Reasoning, emotion, and sensation each have functional and experiential-qualitative aspects, and emotion and sensation are also associated with physiological effects. While the experiential-qualitative aspects of these phenomena resist materialistic explanation, the other aspects do not, which may lead materialists to believe that they are making progress against substance dualism.
Accordingly, I will now suggest a version of substance dualism, which I will label volitional dualism, that does not have this shortcoming. Volitional dualism differs from Cartesian dualism in that the self, the mind, the will, and consciousness are distinguished. A rough characterization of each follows.
The self is the locus of experience, i.e., that which "has" or "undergoes" experiences, or, simply, that which experiences. It is that which unites experiences that are separated in time and space, the "unity of apperception" of Kant's philosophy. It is an irreducible complex consisting of a mind, a will, and consciousness. It is not primarily a "thinking thing", it is a "willing thing".
The mind is a set of perceptual, affective, and information processing functions (a finer grained analysis would separate these functions, but this analysis is adequate for present purposes). As such, it is an abstraction that may be concretized by some combination of the materialist approaches that have been examined so far.
The will is the capacity of the self to originate goals which in turn determine the acts of the self. The self chooses options for action from among those that are (re)presented to the self through the medium of consciousness, in accordance with the goals that the self has willed. While I am assuming that the choice of actions is limited to the options presented to the self, I am purposely leaving open the question of whether there are any limits to the range of goals that the will can originate.
Consciousness is the interaction between the self and all that is not the self via experientialqualitative states. Self-awareness is the inference of self from the unity of conscious experience. Consciousness distills the activity of the mind into qualia, which may represent material or functional states but which are not themselves essentially material or functional. By integrating qualia into a unified experience the self comes to understand what its options for action are, and the relationship between those options and its goals. This understanding allows the self to act in accordance with the goals it has originated.
It would seem that only the mind admits of functional or material explanation. Qualia and self-awareness are constitutive of consciousness, and materialist accounts of these introspective processes have already been shown to be failures. As for the will, I have tacitly assumed that the will is free, and if this assumption is correct, then it would seem difficult to explain the origin of the will in evolutionary terms, since an organism with free will can set goals that jeopardize its ability to survive and reproduce. But if the will is constrained to originate goals that directly or indirectly promote survival and reproduction, then an evolutionary account of volition becomes less improbable.
The application of the above concepts to instrumental rationality may help clarify how the self and its constituents relate to each other, and to the body. Once a goal has been originated, the decision-theoretic procedures involved in evaluating whether a given course of action will promote a given goal may be accounted for using some sort of information processing model, which may in turn be realized materially, in states of the central nervous system. But the origination of (ultimate) goals in the first place cannot be accounted for in terms of information processing. In other words, the will originates goals, and the mind performs the calculations that pertain to the attainment of those goals. But the will can only choose from the options that are presented to it. Consciousness abstracts the huge mass of information involved in mental functions and converts it into qualitative experience, much as Locke's secondary qualities are an abstraction of great masses of data about primary qualities. It is through qualitative experience that the self understands what its options are. The self wills its priorities and chooses options in terms of qualitative experiences; through the medium of consciousness these selections are translated into mental activity and ultimately behavior.
So, for example, a self might select the pursuit of a career as a pitcher in professional baseball as one of its goals. This will entail the performance of numerous activities in various situations, such as attempting to strike out an opposing player in a game. But the pitcher has no direct qualitative experience of the enormous amount of information that is processed by his central nervous system pursuant to the execution of a even a single pitch (experimenters in robotics have found that just programming a bipedal machine to walk is a daunting task). His consciousness abstracts this information into a form that represents the import that this information has with respect to his actual or potential goals.
This of course is only a bare outline of volitional dualism, and therefore suffers from vaguenesses of its own. But I think it suffices to show that, if suitably developed, volitional dualism could be an alternative to both materialism and Cartesian dualism.
Owing partly to a priori considerations and partly to a certain vagueness in Descartes's formulation of substance dualism, many philosophers have been drawn to some form of materialism when confronted with the traditional mind-body problem. Materialism successfully accounts for certain functions that Cartesianism associates with the mind but fails to account for the most interesting features of our inner life. Volitional dualism is a reformulation of substance dualism that takes both the explanatory successes and failures of materialism into account. Such a reformulation emphasizes the importance of consciousness, rather than information processing, as an object of philosophical understanding.
Brenner, William H. Elements of Modern Philosophy: Descartes through Kant. Englewood Cliffs: Prentice Hall, Inc., 1989.
Churchland, Paul. Matter and Consciousness, revised edition. Cambridge: Massachusetts Institution of Technology, 1988.
Descartes, René. Meditations, in Reason and Responsibility, 7th ed.; Joel Feinberg, editor. Belmont: Wadsworth Publishing Co., 1989.
Eliminative materialism (also called eliminativism) is the claim that people's common-sense understanding of the mind (or folk psychology) is false and that certain classes of mental states that most people believe in do not exist. It is a materialist position in the philosophy of mind. Some supporters of eliminativism argue that no coherent neural basis will be found for many everyday psychological concepts such as belief or desire, since they are poorly defined. Rather, they argue that psychological concepts of behaviour and experience should be judged by how well they reduce to the biological level. Other versions entail the non-existence of conscious mental states such as pain and visual perceptions.
Eliminativism about a class of entities is the view that that class of entities does not exist. For example, materialism tends to be eliminativist about the soul; modern chemists are eliminativist about phlogiston; and modern physicists are eliminativist about the existence of luminiferous aether. Eliminative materialism is the relatively new (1960s–1970s) idea that certain classes of mental entities that common sense takes for granted, such as beliefs, desires, and the subjective sensation of pain, do not exist. The most common versions are eliminativism about propositional attitudes, as expressed by Paul and Patricia Churchland,and eliminativism about qualia (subjective interpretations about particular instances of subjective experience), as expressed by Daniel Dennett and Georges Rey. These philosophers often appeal to an introspection illusion.
In the context of materialist understandings of psychology, eliminativism stands in opposition to reductive materialism which argues that mental states as conventionally understood do exist, and that they directly correspond to the physical state of the nervous system.[need quotation to verify] An intermediate position is revisionary materialism, which will often argue that the mental state in question will prove to be somewhat reducible to physical phenomena—with some changes needed to the common sense concept.
Since eliminative materialism claims that future research will fail to find a neuronal basis for various mental phenomena, it must necessarily wait for science to progress further. One might question the position on these grounds, but other philosophers like Churchland argue that eliminativism is often necessary in order to open the minds of thinkers to new evidence and better explanations.
Various arguments have been put forth both for and against eliminative materialism over the last forty years. Most of the arguments in favor of the view are based on the assumption that people's commonsense view of the mind is actually an implicit theory. It is to be compared and contrasted with other scientific theories in its explanatory success, accuracy, and ability to allow people to make correct predictions about the future. Eliminativists argue that, based on these and other criteria, commonsense "folk" psychology has failed and will eventually need to be replaced with explanations derived from the neurosciences. These philosophers therefore tend to emphasize the importance of neuroscientific research as well as developments in artificial intelligence to sustain their thesis.
Philosophers who argue against eliminativism may take several approaches. Simulation theorists, like Robert Gordon and Alvin Goldman argue that folk psychology is not a theory, but rather depends on internal simulation of others, and therefore is not subject to falsification in the same way that theories are. Jerry Fodor, among others, argues that folk psychology is, in fact, a successful (even indispensable) theory. Another view is that eliminativism assumes the existence of the beliefs and other entities it seeks to "eliminate" and is thus self-refuting.
Eliminativism maintains that the common-sense understanding of the mind is mistaken, and that the neurosciences will one day reveal that the mental states that are talked about in everyday discourse, using words such as "intend", "believe", "desire", and "love", do not refer to anything real. Because of the inadequacy of natural languages, people mistakenly think that they have such beliefs and desires. Some eliminativists, such as Frank Jackson, claim that consciousness does not exist except as an epiphenomenon of brain function; others, such as Georges Rey, claim that the concept will eventually be eliminated as neuroscience progresses. Consciousness and folk psychology are separate issues and it is possible to take an eliminative stance on one but not the other. The roots of eliminativism go back to the writings of Wilfred Sellars, W.V. Quine, Paul Feyerabend, and Richard Rorty. The term "eliminative materialism" was first introduced by James Cornman in 1968 while describing a version of physicalism endorsed by Rorty. The later Ludwig Wittgenstein was also an important inspiration for eliminativism, particularly with his attack on "private objects" as "grammatical fictions".
Early eliminativists such as Rorty and Feyerabend often confused two different notions of the sort of elimination that the term "eliminative materialism" entailed. On the one hand, they claimed, the cognitive sciences that will ultimately give people a correct account of the workings of the mind will not employ terms that refer to common-sense mental states like beliefs and desires; these states will not be part of the ontology of a mature cognitive science. But critics immediately countered that this view was indistinguishable from the identity theory of mind. Quine himself wondered what exactly was so eliminative about eliminative materialism after all:
|“||Is physicalism a repudiation of mental objects after all, or a theory of them? Does it repudiate the mental state of pain or anger in favor of its physical concomitant, or does it identify the mental state with a state of the physical organism (and so a state of the physical organism with the mental state)?||”|
On the other hand, the same philosophers also claimed that common-sense mental states simply do not exist. But critics pointed out that eliminativists could not have it both ways: either mental states exist and will ultimately be explained in terms of lower-level neurophysiological processes or they do not. Modern eliminativists have much more clearly expressed the view that mental phenomena simply do not exist and will eventually be eliminated from people's thinking about the brain in the same way that demons have been eliminated from people's thinking about mental illness and psychopathology.
While it was a minority view in the 1960s, eliminative materialism gained prominence and acceptance during the 1980s. Proponents of this view, such as B.F. Skinner, often made parallels to previous pseudoscientific theories (such as that of the four humours, the phlogiston theory of combustion, and the vital force theory of life) that have all been successfully eliminated in attempting to establish their thesis about the nature of the mental. In these cases, science has not produced more detailed versions or reductions of these theories, but rejected them altogether as obsolete. Radical behaviorists, such as Skinner, argued that folk psychology is already obsolete and should be replaced by descriptions of histories of reinforcement and punishment. Such views were eventually abandoned. Patricia and Paul Churchland argued that folk psychology will be gradually replaced as neuroscience matures.
Eliminativism is not only motivated by philosophical considerations, but is also a prediction about what form future scientific theories will take. Eliminativist philosophers therefore tend to be concerned with the data coming from the relevant brain and cognitive sciences. In addition, because eliminativism is essentially predictive in nature, different theorists can, and often do, make different predictions about which aspects of folk psychology will be eliminated from folk psychological vocabulary. None of these philosophers are eliminativists "tout court".
Today, the eliminativist view is most closely associated with the philosophers Paul and Patricia Churchland, who deny the existence of propositional attitudes (a subclass of intentional states), and with Daniel Dennett, who is generally considered to be an eliminativist about qualia and phenomenal aspects of consciousness. One way to summarize the difference between the Churchlands's views and Dennett's view is that the Churchlands are eliminativists when it comes to propositional attitudes, but reductionists concerning qualia, while Dennett is an anti-reductionist with respect to propositional attitudes, and an eliminativist concerning qualia.
Arguments for eliminativism
Problems with folk theories
Eliminativists such as Paul and Patricia Churchland argue that folk psychology is a fully developed but non-formalized theory of human behavior. It is used to explain and make predictions about human mental states and behavior. This view is often referred to as the theory of mind or just simply theory-theory, for it is a theory which theorizes the existence of an unacknowledged theory. As a theory in the scientific sense, eliminativists maintain, folk psychology needs to be evaluated on the basis of its predictive power and explanatory success as a research program for the investigation of the mind/brain.
Such eliminativists have developed different arguments to show that folk psychology is a seriously mistaken theory and needs to be abolished. They argue that folk psychology excludes from its purview or has traditionally been mistaken about many important mental phenomena that can, and are, being examined and explained by modern neurosciences. Some examples are dreaming, consciousness, mental disorders, learning processes, and memory abilities. Furthermore, they argue, folk psychology's development in the last 2,500 years has not been significant and it is therefore a stagnating theory. The ancient Greeks already had a folk psychology comparable to modern views. But in contrast to this lack of development, the neurosciences are a rapidly progressing science complex that, in their view, can explain many cognitive processes that folk psychology cannot.
Folk psychology retains characteristics of now obsolete theories or legends from the past. Ancient societies tried to explain the physical mysteries of nature by ascribing mental conditions to them in such statements as "the sea is angry". Gradually, these everyday folk psychological explanations were replaced by more efficient scientific descriptions. Today, eliminativists argue, there is no reason not to accept an effective scientific account of people's cognitive abilities. If such an explanation existed, then there would be no need for folk-psychological explanations of behavior, and the latter would be eliminated the same way as the mythological explanations the ancients used.
Another line of argument is the meta-induction based on what eliminativists view as the disastrous historical record of folk theories in general. Ancient pre-scientific "theories" of folk biology, folk physics, and folk cosmology have all proven to be radically wrong. Eliminativists argue the same in the case of folk psychology. There seems no logical basis, to the eliminativist, for making an exception just because folk psychology has lasted longer and is more intuitive or instinctively plausible than the other folk theories. Indeed, the eliminativists warn, considerations of intuitive plausibility may be precisely the result of the deeply entrenched nature in society of folk psychology itself. It may be that people's beliefs and other such states are as theory-laden as external perceptions and hence intuitions will tend to be biased in favor of them.
Specific problems with folk psychology
Much of folk psychology involves the attribution of intentional states (or more specifically as a subclass, propositional attitudes). Eliminativists point out that these states are generally ascribed syntactic and semantic properties. An example of this is the language of thought hypothesis, which attributes a discrete, combinatorial syntax and other linguistic properties to these mental phenomena. Eliminativists argue that such discrete and combinatorial characteristics have no place in the neurosciences, which speak of action potentials, spiking frequencies, and other effects which are continuous and distributed in nature. Hence, the syntactic structures which are assumed by folk psychology can have no place in such a structure as the brain. Against this there have been two responses. On the one hand, there are philosophers who deny that mental states are linguistic in nature and see this as a straw man argument. The other view is represented by those who subscribe to "a language of thought". They assert that the mental states can be multiply realized and that functional characterizations are just higher-level characterizations of what's happening at the physical level.
It has also been argued against folk psychology that the intentionality of mental states like belief imply that they have semantic qualities. Specifically, their meaning is determined by the things that they are about in the external world. This makes it difficult to explain how they can play the causal roles that they are supposed to in cognitive processes.
In recent years, this latter argument has been fortified by the theory of connectionism. Many connectionist models of the brain have been developed in which the processes of language learning and other forms of representation are highly distributed and parallel. This would tend to indicate that there is no need for such discrete and semantically endowed entities as beliefs and desires.
Arguments against eliminativism
The thesis of eliminativism seems to be so obviously wrong to many critics, under the claim that people know immediately and indubitably that they have minds, that argumentation seems unnecessary. This sort of intuition pumping is illustrated by asking what happens when one asks oneself honestly if one has mental states. Eliminativists object to such a rebuttal of their position by claiming that intuitions often are mistaken. Analogies from the history of science are frequently invoked to buttress this observation: it may appear obvious that the sun travels around the earth, for example, but for all its apparent obviousness this conception was proved wrong nevertheless. Similarly, it may appear obvious that apart from neural events there are also mental conditions. Nevertheless, this could equally turn out to be false.
But even if one accepts the susceptibility to error of people's intuitions, the objection can be reformulated: if the existence of mental conditions seems perfectly obvious and is central in people's conception of the world, then enormously strong arguments are needed in order to successfully deny the existence of mental conditions. Furthermore, these arguments, to be consistent, need to be formulated in a way which does not pre-suppose the existence of entities like "mental states", "logical arguments", and "ideas", otherwise they are self-contradictory. Those who accept this objection say that the arguments in favor of eliminativism are far too weak to establish such a radical claim; therefore there is no reason to believe in eliminativism.
Some philosophers, such as Paul Boghossian, have attempted to show that eliminativism is in some sense self-refuting, since the theory itself presupposes the existence of mental phenomena. If eliminativism is true, then the eliminativist must permit an intentional property like truth, supposing that in order to assert something one must believe it. Hence, for eliminativism to be asserted as a thesis, the eliminativist must believe that it is true; if that is the case, then there are beliefs and the eliminativist claim is false.
Georges Rey and Michael Devitt reply to this objection by invoking deflationary semantic theories that avoid analysing predicates like "x is true" as expressing a real property. They are construed, instead, as logical devices so that asserting that a sentence is true is just a quoted way of asserting the sentence itself. To say, "'God exists' is true" is just to say, "God exists". This way, Rey and Devitt argue, insofar as dispositional replacements of "claims" and deflationary accounts of "true" are coherent, eliminativism is not self-refuting.
Another problem for the eliminativist is the consideration that human beings undergo subjective experiences and, hence, their conscious mental states have qualia. Since qualia are generally regarded as characteristics of mental states, their existence does not seem to be compatible with eliminativism. Eliminativists, such as Daniel Dennett and Georges Rey, respond by rejecting qualia. This is seen to be problematic to opponents of eliminativists, since many claim that the existence of qualia seems perfectly obvious. Many philosophers consider the "elimination" of qualia implausible, if not incomprehensible. They assert that, for instance, the existence of pain is simply beyond denial.
Admitting that the existence of qualia seems obvious, Dennett nevertheless states that "qualia" is a theoretical term from an outdated metaphysics stemming from Cartesian intuitions. He argues that a precise analysis shows that the term is in the long run empty and full of contradictions. The eliminativist's claim with respect to qualia is that there is no unbiased evidence for such experiences when regarded as something more than propositional attitudes. In other words, they do not deny that pain exists, but that it exists independently of its effect on behavior. Influenced by Ludwig Wittgenstein's Philosophical Investigations, Dennett and Rey have defended eliminativism about qualia, even when other portions of the mental are accepted.
Efficacy of folk psychology
Some philosophers simply argue that folk psychology is a quite successful theory. Simulation theorists doubt that people's understanding of the mental can be explained in terms of a theory at all. Rather they argue that people's understanding of others is based on internal simulations of how they would act and respond in similar situations.Jerry Fodor is one of the objectors that believes in folk psychology's success as a theory, because it makes for an effective way of communication in everyday life that can be implemented with few words. Such an effectiveness could never be achieved with a complex neuroscientific terminology.
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