The Mind-Body Problem IA
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The Mind-Body Problem IA
Consciousness and Property Dualism or Mere-Property Dualism
How can mere matter originate consciousness? How did evolution convert the water of biological tissue into the wine of consciousness? Consciousness seems like a radical novelty in the universe, not prefigured by the after-effects of the Big Bang; so how did it contrive to spring into being from what preceded it?
Colin McGinn, The Mysterious Flame
It seems to me that science is increasingly giving us a viewpoint whereby organisms are able to be seen as physicochemical mechanisms. . . . There does seem to be, so far as science is concerned, nothing in the world but increasingly complex arrangements of physical constituents. All except for one place: in consciousness. . . . I just cannot believe that this can be so. That everything should be explicable in terms of physics . . . except the occurrence of sensations seems to me to be frankly unbelievable.
J. J. C. Smart, “Sensations and Brain Processes”
We commonly think that we, as persons, have a mental and bodily dimension. . . . Something like this dualism of personhood, I believe, is common lore shared across most cultures and religious traditions.
Jaegwon Kim, “Lonely Souls: Causality and Substance Dualism”
1—Introduction
It is virtually self-evident to most people that they are different from their bodies. Almost all societies throughout history (unless they are taught to think otherwise) have believed in some form of life after death, and this belief arises naturally when a human being reflects on his or her own constitution. Moreover, throughout church history, the vast majority of Christian thinkers have correctly understood the Scriptures to teach the following: (1) Human beings exhibit a holistic functional unity. (2) While a functional unity, humans are nevertheless a duality of immaterial soul/spirit and material body, both of which are intrinsically good. Setting aside the question of whether the soul and spirit are the same or different, and acknowledging that the biblical terms for soul (nepeš, psychē) and spirit (rûaḥ, pneuma) have a wide variety of different meanings, it is still clear that the Scriptures teach that the soul/spirit is an immaterial component different from the body (Eccles 12:7; Mt 10:28), that death involves the soul’s leaving the body (Gen 35:18; 1 Kings 17:21-22), and that after death the soul continues to exist in a disembodied intermediate state while awaiting the resurrection of the body (Lk 23:46; 2 Cor 5:1-10; Phil 1:21-24; Heb 12:23). (3) Since animals are living creatures, they have souls as well, those souls are different from human souls, and animals are not likely to survive death (Gen 1:30; Rev 8:9).
This biblical teaching must be integrated with an area of philosophy known as philosophy of mind. A main part of the philosophy of mind is something called the mind-body problem, which will occupy our attention in this and the next three chapters.
There are two central areas of debate regarding the mind-body problem. First, there is a debate about the nature of consciousness or mental properties/states, which we shall discuss in chapters eleven and twelve. In this chapter we shall look at issues involving property dualism (and mere-property dualism defined below)—the claim that consciousness or mental properties/states are immaterial and not physical. In chapter twelve, we shall continue our discussion of the nature of consciousness or mental properties/states by looking at physicalist alternatives to property dualism regarding consciousness. In chapters thirteen and fourteen we shall follow the same pattern in discussing the second central area of debate regarding the mind-body problem: the nature of the subject, bearer or possessor of consciousness. In chapter thirteen we shall examine issues involving different versions of substance dualism—the claim that the subject of consciousness is immaterial, not physical. These versions all hold that the subject of consciousness is a soul, self, or mind that is distinct from the body. In chapter fourteen we shall investigate physicalist alternatives to substance dualism which claim that something physical is the bearer of consciousness.
In this chapter, we will look at the following topics: preliminary issues, the nature of consciousness, arguments for property dualism (or mere-property dualism), and arguments against property dualism.
2—Preliminary Issues
2.1 The Mind-Body Problem(s)
In some contexts, it is possible and important to make a distinction among the mind, the soul, the spirit, and the ego or the self. But for our purposes, we will use these interchangeably. Our main concern here is to clarify two preliminary issues beginning with a statement of the mind-body problem, which, in turn, involves two main issues. First, is consciousness, or are mental properties, physical or irreducibly mental, and is the human self (if there is such a thing) physical or immaterial? If the answer is that consciousness/mental properties are not physical and the human person involves two components, do mind and matter interact, and if so, how does that interaction take place?
The second preliminary issue is to provide an overview of the main options regarding the nature of consciousness and the nature of the human person. Let us begin with the different positions regarding consciousness (e.g., sensations, thoughts) as depicted in figure 11.1.
Figure 11.1. Positions taken on the nature of consciousness/mental properties
The two main views of mental consciousness/mental properties are physicalism and dualism. As we can see in figure 11.1, there are different versions of each. Physicalists claim that in one way or another, consciousness is completely physical. We will examine and critique each version of physicalism regarding mental properties in the next chapter. Dualism regarding consciousness comes in two versions. First, mere-property dualism acknowledges that mental properties/consciousness are in no way physical and, in fact, are irreducibly mental. But mere-property dualists go on to assert that the brain or some other physical object (e.g., the body) is the bearer or subject of consciousness. This is usually (though not always) associated with emergentism, the view that when matter reaches a certain level of complexity, a new kind of simple property (e.g., painfulness) arises that in no way characterizes the physical base (the brain) that gave rise to it. Consciousness is in and dependent on the brain. By contrast, property dualism simpliciter (which we will refer to as “property dualism”) holds that not only is consciousness immaterial, but so is the bearer or subject of consciousness—for example, a soul, mind, self. In this way property dualism implies substance dualism but mere-property dualism does not. From figure 11.1 you can see that there are two versions of nonreductive physicalism. In the next chapter we will clarify version 1 (usually expressed as a version of functionalism). But for now, we note that version 2 is actually a form of mere-property dualism. Thus version 2 is physicalist regarding the possessor/subject of consciousness but dualist regarding consciousness itself.
Now look at figure 11.2 regarding that to which a human person is identical.
Figure 11.2. Positions taken on the identity of the human person or the subject of consciousness
As with figure 11.1, the physicalist views in 11.2 will be treated in a subsequent chapter.
What exactly is physicalism? It is hard to say precisely because, as noted above, several different views go by this name. Sometimes physicalism refers to whatever version of it is currently fashionable. However, we can be more precise. Note first of all that, historically speaking, materialism was the view that the only substances that exist are material substances, but (1) some of these substances (living organisms) may possess a duality of material and immaterial properties and (2) immaterial abstract objects (e.g., sets, universals) may also exist (see chap. 10 for a discussion of substance, i.e., a whole that is a deep unity of properties, parts, and capacities). Today, physicalism often means something more restrictive than materialism so defined: physicalism can be understood as the view that all entities whatsoever are merely physical entities. This view should be called “strict physicalism.” There are no abstract objects (although some who identify with strict physicalism would accept abstract objects), and all substances, properties, and events are merely physical entities. By contrast, some physicalists hold that while there are only physical substances, there are genuinely mental properties that emerge from and are dependent on their physical bases. This view seems to be a version of mere-property dualism, and we will treat it as such.
What is meant by a physical entity? Three different things can be meant here. First, physical can mean whatever can be described using the language of physics and chemistry. Second, physical can include the sense just given and be extended to include whatever can be described in any physical science, especially biology. Third, physical can be extended beyond the first two senses to include any commonsense notion of physical. This is often taken to include the primary qualities (shape, mass, size, motion) and to exclude the secondary qualities (those experienced through only one sense organ such as color, smell, texture, sound, taste). The restricted sense of physicalism, therefore, implies that all entities whatever are merely physical in one of these three senses.
We will use physicalism in this more restricted sense and understand physical to mean whatever can be described using the language of physics and chemistry: Only various configurations and hierarchies of elementary particles can be said to exist. This sense of physical is widely used by physicalists in stating and defending their views, and it captures what is, for many, the driving force behind physicalism: the unity and authority of science. The unity of science means, among other things, that a completely developed physics and chemistry could give a complete, unified description and explanation of all phenomena because the world is one physical system. The authority of science means either that the hard sciences and the hard sciences alone give us rational beliefs and knowledge about the real world (strong scientism) or that while disciplines outside the hard sciences may give us fairly weakly justified beliefs, nevertheless, the authority of science is vastly superior to these other disciplines.
According to strict physicalism, a human being is merely a physical entity. The only things that exist are physical substances, properties, and events. When it comes to humans, the physical substance is the living body or brain and central nervous system. The physical substance called the brain has physical properties, such as a certain weight, volume, size, electrical activity, and chemical composition.
There are also physical events that occur in the brain. For example, the brain contains a number of elongated cells that carry various impulses. These cells are called neurons. Various neurons make contact with other neurons through connections or points of contact called synapses. C fibers are certain types of neurons that innervate the skin (i.e., supply the skin with nerves) and carry “pain impulses.” According to physicalism, when someone has an occasion of pain or an occurrence of a thought, these are merely physical events, namely, events where such and such C fibers are firing or certain electrical and chemical events are happening in the brain and central nervous system. Thus physicalists believe that a human is merely a physical thing (a brain and central nervous system or a living body) that has physical properties and in which physical events occur.
What is matter? There is no clear definition of matter, and in fact we know precious little about what matter actually is. But examples of matter are not hard to come by. Material objects are things like computers, neurons, carbon atoms, and billiard balls.
Physical properties are the properties that are possessed only by physical objects. They are the properties that one finds listed in chemistry or physics books, for example, hardness; occupying and moving through space; having a certain shape; possessing certain chemical, electrical, magnetic, and gravitational properties; having density and mass; and being breakable, malleable, and elastic. A physical event is the continued possession, coming, or going of one or more of these properties by a physical substance (or among physical substances) at a time.
There is one very crucial observation to make about material substances, properties, and events. No material thing presupposes or requires reference to consciousness for it to exist or be characterized. You will search in vain through a physics or chemistry textbook to find consciousness included in any description of matter. A completely physical description of the world would not include any terms that make reference to or characterize consciousness.
Property and substance dualists disagree with physicalists. According to the former two, mental entities are real, and the mind and its contents are radically nonphysical. As with matter, it is hard to give a definition of mental entities. Some have defined a mental entity as something such that it would not exist if there were no sentient creatures. Others define a mental entity as something about which the subject is in a better position to know than is anyone else, or something to which a subject has private, first-person access. Mental entities belong to the private world of inner experience.
Regardless of how we define a mental entity, examples of them are easy to supply: feeling anger or pain, thinking about lunch, believing that 2 + 2 = 4, desiring ice cream, and so on. In the next section we will give a fuller analysis of consciousness, followed by a section presenting arguments for its irreducibly mental nature.
2.2 Dualist Strategies Regarding Consciousness and the Soul
Our discussion of identity in chapter nine stated that if two entities x and y are identical, then whatever is true of x will be true of y and vice versa, because x is the very same entity as y. Moreover, something does not just happen as a matter of contingent fact to be identical to itself. Thus, if x is identical to y, then it is necessarily the case that x is identical to y. It is metaphysically impossible to have one without the other because “they” are necessarily identical. Physicalists are committed to the claim that alleged mental entities either do not exist at all or if they do, are really identical to physical entities, for example, brain states, properties of the brain, overt bodily behavior, or dispositions to behave (e.g., pain is just the tendency to shout “ouch!” when stuck by a pin instead of being a certain mental feel, namely, hurtfulness). If physicalism is true and if mental entities exist but are really nothing but physical entities, then everything true of the brain or the living body (and its properties, states, and dispositions) is true of the mind (and its properties, states, and dispositions) and vice versa. If we can find one thing true, or even possibly true, of the mind (or its states) and not the brain or living body (or its states), or vice versa, then some form of dualism is established. The mind or its states are not physical.
Keep in mind that the relation of identity is different from any other relation—for example, causation or constant connection. It may be that brain events cause mental events or vice versa (e.g., having certain electrical activity in the brain may cause one to experience a pain, and having an intention to raise one’s arm may cause bodily events). It may be that for every mental activity a neurophysiologist can find a physical activity in the brain with which it is correlated or upon which it is dependent. But just because A causes B (or vice versa), or just because A and B are constantly correlated with each other, that does not mean that A is identical to B. Something is trilateral if and only if it is triangular. But trilaterality (the property of being three-sided) is not identical to triangularity (the property of being three-angled), even though they are necessarily constantly conjoined.
To establish physicalism, it is not enough that mental states and brain states are causally related or constantly conjoined with each other in an embodied person. Physicalism needs identity to make its case, and if something is true, or possibly true of a mental substance, property, or event that is not true, or possibly true of a physical substance, property, or event, physicalism is false.
Thus the first dualist strategy is to establish nonidentity between mental properties/states and physical properties/states (chaps. 11 and 12) and between the self/soul and the brain or living body (chaps. 13 and 14). A second dualist strategy is to argue that certain features seem to be true of us—we sustain literal identity over time even though we change in accidental ways, we possess libertarian free will—that could not be true of us if we were identical to a physical particular. These features are best explained if we are souls/immaterial selves.
3—An Overview of Consciousness
The nature of consciousness is pretty commonsensical. Suppose you are in the recovery room immediately after surgery. You are still deeply under anesthesia. Suddenly and somewhat faintly, you begin to hear sounds. It is not long until you can distinguish two different voices. You begin to feel a dull throb in your ankle. The smell of rubbing alcohol wafts past your nose. You remember a childhood accident with the same smell. You feel an aversion toward it. You feel thirsty and desire a drink. As you open your eyes to see a white ceiling above, you begin to think about getting out of the hospital. What is going on? The answer is simple: you are regaining consciousness.
Note two things about this example. First, whereas any physical object (state, process, property, relation) can and only can be completely described from within a third-person perspective, descriptions of states of consciousness require an approach from within the first-person point of view. Second, states of consciousness are best defined ostensively: by citing or pointing to specific examples. In fact, a fairly good characterization of consciousness is this: consciousness is what you are aware of when you engage in first-person introspection. Both of these observations are exactly what the dualist approach to consciousness would predict.
Besides defining consciousness, we can also characterize different features of consciousness. First, there is phenomenal consciousness. Phenomenal properties (also called qualia [the plural of quale]) or phenomenal conscious states are such that there is a raw feel or a what-it-is-like to be in that state. There is a what-it-is-like to being in pain, tasting a lemon, hearing the note C, or being yourself. Some philosophers limit phenomenal consciousness to sensations. Now it seems correct to say that the what-it-is-like to feeling pain or tasting a lemon is more vivid than the what-it-is-like to having a thought (say, the thought that George Washington was the first president of the United States) or a belief (e.g., entertaining your belief that snow is white). But it is far too restrictive to limit phenomenal consciousness to sensations. If thoughts, beliefs, and desires have no introspectively discernible difference among them, one could never know what thought, belief, or desire one was having by simple introspection. But we do this all the time. Two different thoughts, for example, the one about Washington and the one about snow, have introspectively discernible differences, and these differences amount to there being a different what-it-is-like to having each thought.
Second, there is what we may call the epistemic subjectivity of consciousness, which involves three different aspects of consciousness. For one thing, consciousness exhibits direct access. I can be aware of a physical object or state (e.g., water’s being solid) by means of having a sensation of the physical entity. But my access to my own conscious states, for example, a state of pain, is direct and does not require me to be aware of the pain by having a second-order state of awareness directed at the pain (though, of course, I can do this if I wish). No, by simply having the pain, I have a pain awareness that is direct to me and not presented by means of another sensation. Sometimes this point is put by saying that the properties of consciousness are self-presenting properties. If I instantiate the property of being-a-sensation-of-red while looking at an apple, this property presents two different objects to me: the intentional object—the apple’s surface—which is indirectly presented to me by means of the sensation of red, and the sensation of red itself, which is directly accessible to me. By contrast, no physical object, state, or property is such that I have direct access to it. For example, my access to one of my own brain states is achieved indirectly by directing my awareness to my brain state or by reading a monitor that registers my brain states.
Additionally, the epistemic subjectivity of consciousness exhibits epistemic authority. Assuming I am focusing on my inner life and not daydreaming, I am in a position to know what is happening in my own mental life with greater epistemic certainty than other people have in knowing what is in my conscious life. A neuroscientist could know with greater certainty what is happening in my brain, but cannot know with greater certainty what is going on in my own mind. One might think that the day will come in which scientists have so precisely correlated mental and brain states that a scientist could, indeed, know better than I what is going on in my mental life by simply reading my brain states. But this is not true. Why? In order for scientists to develop a detailed chart correlating specific mental and physical states, he must ask his experimental subjects what is going on inside them as he reads the bran monitor. Thus any correlation chart will be epistemically dependent on and weaker than a subject’s own introspective knowledge of his conscious states because the chart is dependent on the accuracy of experimental subjects’ reports of their own consciousness.
Finally, the epistemic subjectivity of consciousness exhibits private access. Take any physical entity whatsoever—a rock, an organic chemical, or a state of the brain. Any way you have of knowing things about that physical entity (e.g., its size, shape, mass) is available to me. If you need to measure it to know its length, then I can do that too. But I have a way of knowing about my own conscious states that is not available to you—by direct introspection. As Thomas Nagel and others have pointed out, we could know everything there was to know about the physical aspects of a bat, but we would still have no clue as to the facts about what-it-is-like to be a bat. These are privately accessible to the bat.
Now some philosophers claim that that epistemic subjectivity and its three features are mere epistemic items that have no ontological implications. More specifically, epistemic subjectivity does not show that conscious states are irreducibly immaterial and not identical to brain states. Just as there are two ways of knowing an apple (by seeing and feeling it), yet it is the same object known in each case (the apple), in the same way, there may be two ways of knowing states of the brain (by first-person introspection, characterized by direct access, epistemic authority and private access, and by grasping third-person neuroscientific theory about brain states). But that does not show there are two different things—conscious and brain states. No, all it shows is that there are two different ways of knowing brain states.
In response, we make two points. First, it is far from clear that a “way of knowing” is physical. For example, ways of knowing have intentionality (ofness about the object of knowledge) and normativity (under certain circumstances, one ought to accept the knowledge provided by a certain way of knowing), but mere physical states of the brain possess neither. Second, the three features of epistemic subjectivity mentioned above are straightforwardly ontological and not merely epistemic. How so? If a person is merely a physical object, say, a brain, consisting entirely of physical states, then the three features of epistemic subjectivity would not be genuine because they do not apply to physical states. It is only if conscious states are immaterial that we have an explanation as to why these three features are genuine: they involve different ways of relating to a nonphysical state; they do not even apply to ways of relating to physical states.
Third, consciousness exhibits what is called point-of-view subjectivity, which, in turn, involves at least two different features of consciousness. To begin with, it seems that, necessarily, for any conscious state whatsoever, it belongs to a subject of experience. The ideal of a subjectless conscious state just floating around without being owned by a subject is ridiculous. However, it is hard if not impossible to make a case that some physical states are necessarily such that they must belong to a subject. Further, conscious states are always features of a subjective point of view. That is, they characterize the subject’s unique and distinct standing point in the world in virtue of which he is aware of and thinks about the world.
Some philosophers, for example, Lynne Rudder Baker, believe that the first-person point of view is a property that a person has (exemplifies). An example would be the person Smith having the property of being-the-first-person-point-of-view. But for two reasons, this seems to be mistaken. For one thing, if there is such a property, it is an impure one. An impure property, for example, being-identical-to-Socrates or to-the-left-of-a-desk, requires reference to a particular (Socrates, the desk) to be described. Such a property cannot constitute the particular (Socrates, the desk) without being circular: the property being-identical-to-Socrates presupposes and, therefore, cannot constitute or individuate the particular—Socrates—to which reference is made.
In the same way, if the person Smith has the property of being-the-first-person-point-of-view, the property already presupposes the existence of a person, in this case, Smith, to have the property. If this is correct, then Smith is already a person ontologically prior to having the first-person-point-of-view. Philosopher Kevin Corcoran is in agreement with Lynne Baker about the role of the first-person perspective in constituting personhood. He notes, “Persons are also the only sorts of thing that have what Lynne Baker calls a first-person perspective.” Note that things like an apple have a property (being red) by way of exemplification. The apple exemplifies being red. But regarding exemplification, the thing having the property (the apple) has to exist ontologically prior to exemplifying the property (being red). Similarly, if, as Corcoran correctly notes, persons have—that is, exemplify—being-the first-person perspective, then persons must exist ontologically prior to having this property. If follows, then, that having the property of being-the-first-person-perspective cannot constitute what it is to be a person, since that property presupposes persons exist in order to exemplify the property in the first place.
For another thing, there most likely is no such property. In general, one may give a reductive analysis of the first-person perspective as follows: S has the property of being-a-first-person perspective if S is a personal, viewing kind of point, that is, S is a kind of substance (point), a sentient (viewing) substance, with the properties (including ultimate potentialities) characteristic of persons (e.g., self-awareness). The first-person perspective is not a property persons have; it is the thing persons are—substantial centers of a personal kind of consciousness. Persons qua substantial, unified centers exemplify ordinary mental properties—being-a-thought-that-P, being-a-sensation-of-red, being painful. But they do not have, in addition to these, the property of being-a-first-person-perspective. When a substantial personal ego exemplifies an ordinary mental property, that is ipso facto a first-person perspective. There is no additional fact that needs grounding in a superfluous property—being-a-first-person-perspective. The “first-person perspective” is just a way of describing/referring to an ontologically prior substantial, sentient person with ordinary mental properties to which the “first-person perspective” can be reduced.
So far, we have provided an ostensive definition of consciousness and offered different ways of characterizing it. In addition to these, philosophers sometimes distinguish two different kinds of consciousness—phenomenal consciousness and access consciousness. We have already characterized phenomenal consciousness as the raw feel/texture or the what-it-is-like to a conscious state. But further, a state of consciousness is an example of access consciousness if and only if that state is available for (1) guiding speech and verbal reports, (2) directing and controlling action and body movements, or (3) use in reasoning.
It is clear that you can have phenomenal consciousness without access consciousness. Suppose you are looking at a chart with three columns and four rows with each place on the chart containing a different number. Clearly, there would be a what-it-is-like to be aware of the chart (you would have phenomenal consciousness with respect to the chart), but you would not have access consciousness toward the chart because each number on the chart would not be available to you for verbally reporting that number, guiding your behavior (e.g., reproducing a chart from memory with each number in the right place), and for reasoning (e.g., reasoning that a given number is even and not odd). There is no puzzle to this. We are often aware of more than we can recall and to which we have access.
More controversially, some think you can have access consciousness without phenomenal consciousness. Consider cases of blind sight. These cases involve people who have a large “hole” in the center of their visual field such that they don’t seem to be aware of objects in the center of their field, but they are aware of objects outside the “hole” on the periphery of their field. In experiments, psychologists place different shaped objects in the area where the subjects have blind sight and, thus, apparently no awareness of the object (no phenomenal consciousness). Yet when asked about the shape of the object, blind sight subjects report those shapes in a statistically relevant, accurate way. What should we make of these findings? At least two interpretations are possible. First, the subject has no phenomenal consciousness of the objects, but the wavelengths that still reach and stimulate the brain trigger familiar neural pathways that fire when a certain shape appears, and those pathways produce accurate verbal reports spontaneously. Second, the subjects do, indeed, have a first-order awareness of the objects and their shapes, but their defect blocks them from having a second-order awareness of this first-order awareness. Thus, while the subjects are aware of the objects, they are not aware of being aware of them, and it is this second-order awareness that is required for accurate verbal reports.
Finally, we should mention that at least five kinds of conscious states exist. In our view, all of them exhibit phenomenal consciousness. A sensation is a state of awareness or sentience, for example, a conscious awareness of sound or pain. Some sensations are experiences of things outside me like a tree or the color red. Others are awarenesses of states within me like pains. Emotions are a subclass of sensations, and as such, they are forms of awareness of things. I can be aware of something in an angry way. A thought is a mental content that can be expressed in an entire sentence. Some thoughts logically imply other thoughts. For example, “All dogs are mammals” entails “Some dogs are mammals.” If the former is true, the latter must be true. Some thoughts don’t entail but merely provide evidence for other thoughts. For example, certain thoughts about evidence in a court case provide grounds for the thought that a person is guilty. Thoughts are the sorts of things that can be true or false, reasonable or unreasonable. A belief is a person’s view, accepted to varying degrees of strength, of how things really are. A desire is a certain felt inclination to do, have, or experience certain things or to avoid such. An act of will is a choice, an exercise of power, an endeavoring to act, usually for the sake of some purpose.
4—Arguments for Property Dualism or Mere-Property Dualism and the Immaterial Nature of Mental States
Are properties such as being a pain or a thought, and the states/events composed of them (a pain or thinking event), genuinely mental or are they physical? In this section, we will look at a case for property dualism or mere-property dualism, the view that conscious properties/events are mental and not physical. In order to follow the case, remember the law of identity: if x is identical to (is the same thing as) y, then whatever is true of x is true of y and vice versa. If we can find one thing true or possibly true of x not true or possibly true of y, they are not the same thing, even if one of the two depends on the other for its functioning.
4.1 Clear Differences Between Conscious and Physical Properties/States
Property dualists argue that mental states are in no sense physical since they possess five features that do not characterize physical states:
(a) There is a raw qualitative feel or a “what-it-is-like” to having a mental state such as a pain.
(b) At least many mental states have intentionality—ofness or aboutness—directed toward an object.
(c) Mental states are inner, private, and immediate to the subject having them.
(d) Mental states require a subjective ontology—namely, mental states are necessarily owned by the sentient subjects who have them.
(e) Mental states fail to have crucial features (e.g., spatial extension, location, being a structural property composed of parts like the state of being a neuron) that characterize physical states and, in general, cannot be described using physical language.
Once one gets an accurate description of consciousness (see above), it becomes clear that mental properties/events are not identical to physical properties/events. Mental states are characterized by their intrinsic, subjective, inner, private, qualitative feel, made present to a subject by first-person introspection. There is a what-it-is-like to being a pain, a sensation of pleasure, a thought of George Washington, and so forth. But there is no what-it-is-like to being an electron, being a neuron, being a pattern of synaptic firing, or to any physical state whatsoever. Further, mental states cannot be intrinsically described by physical language, even if, through study of the brain, one can discover the causal/functional relations between mental and brain states. But brain states can be exhaustively and intrinsically described by physical language.
As mentioned in the previous section, mental states have a nonphysical nature that qualifies them to be related to the three features of epistemic subjectivity—direct access, epistemic authority, private access. By contrast, physical states—for example, brain states—are such that they must be accessed indirectly, and they are public entities such that epistemic authority and private access do not make any sense with respect to them.
Some sensations are pleasurable or unpleasant, but nothing physical has these properties. A cut in the knee is, strictly speaking, not unpleasant. It is the pain event caused by the cut that is unpleasant. Mental states can have the property of familiarity (e.g., when a desk looks familiar to someone), but familiarity is not a feature of a physical state. When one has a pain, a number of neurons called C fibers engage in synaptic firing. Now, the property of being a C fiber firing is an extremely complicated structural property made up of myriads of atoms, molecules, and neurons all placed in very complicated geometrical structure and exhibiting a complicated structure of synaptic firing. But being a pain is a simple quality; it is not built up out of myriads of parts placed in a complicated structure.
Since mental states have these features and physical states do not, mental states are not identical to physical states. Some physicalists have responded by denying that consciousness has the features in question. For example, dualists have argued that thinking events have no geometrical properties (size, shape, location) even though the brain event associated with them does. Physicalists counter that thoughts are, after all, located in certain places of the brain. But there is no reason to accept this claim, since dualists can account for all the spatial factors in terms of the brain events causally related to thoughts. It is the brain events associated with thoughts that have spatial features (size, shape, location), features that can be projected onto a computer screen; it is not the thinking events that have these spatial features. Indeed, it seems to be a category fallacy to ask how large and what is the shape of my thought of George Washington, and whether it is closer to or further away from my left ear than my thought of snow. Moreover, through introspection, subjects seem to know quite a bit about the features of their thoughts, and spatial location is not one of them. Similar responses are offered by dualists for physicalist claims about the other features of consciousness.
4.2 The Knowledge Argument
A second argument for property/event dualism is the knowledge argument, variously formulated by Thomas Nagel, Frank Jackson (who has subsequently abandoned the argument for reasons we believe are inadequate), and Saul Kripke. A standard presentation of the thought experiment has it that Mary, a brilliant scientist blind from birth, knows all the physical facts relevant to acts of perception. When she suddenly gains the ability to see, she gains knowledge of new facts. Since she knew all the physical facts before recovery of sight, and since she gains knowledge of new facts, these facts must not be physical facts, and moreover, given Mary’s situation, they must be mental facts.
To appreciate the argument, it is necessary to focus on the nature of self-presenting properties and three kinds of knowledge. First, recall that a self-presenting property, such as being an appearing of red, presents both its intentional object (say, the red apple) and itself to the subject exemplifying it. When a person is sensing an apple, he is aware of the apple and he is also having the experience of seeing the apple. Second, arguably, there are three forms of knowledge, irreducible to each other, though of course one form may be the epistemic ground for another: (1) Knowledge by acquaintance: One has such knowledge when one is directly aware of something; for example, when one sees an apple directly before him, one knows it by acquaintance. One does not need a concept of an apple or knowledge of how to use the word apple to have knowledge by acquaintance of an apple. (2) Propositional knowledge: This is knowledge that a proposition is true. For example, knowledge that “the object there is an apple” requires having a concept of an apple and knowing that the object under consideration satisfies the concept. (3) Know-how: This is the ability to do certain things, for example, to use apples for certain purposes.
Generally, knowledge by acquaintance provides grounds for propositional knowledge that, in turn, provides what is necessary to have genuine know-how. It is because one sees the apple that one knows it is an apple, and it is in virtue of one’s knowledge of apples that one has the skill to do things to or with them.
By way of application, Mary comes to have the self-presenting mental property of being-an-appearing-of-red (she experiences a sensation of redness). In this way, Mary gains six new kinds of knowledge—she gains knowledge by acquaintance, propositional knowledge, and skill both with regard to the color red and her sensation of red. Mary now knows by acquaintance what redness is. Upon further reflection and experience, she can now know things like “Necessarily, red is a color.” She also gains skill about comparing or sorting objects on the basis of their color, about how to arrange color patterns that are most beautiful or natural to the eye, and so on. Assuming a realist, and not a representative, dualist construal of secondary qualities (secondary qualities are colors, sounds, tastes, smells, textures, and a realist view of them implies that objects in the world have these features; so when a tree falls in the forest with no one around, there is, indeed, a sound!), we may say that the three kinds of knowledge just listed are not themselves knowledge of mental facts, but are forms of knowledge that can be gained only by way of mental states that exemplify the relevant self-presenting property (only by having a sensation of red can I have these forms of knowledge about redness).
Further, Mary gains knowledge about her sensation of red. She is now aware of having a sensation of red for the first time and can be aware of a specific sensation of red being pleasurable, vague, and so on. She also has propositional knowledge about her sensations. She could know that a sensation of red is more like a sensation of orange than it is like a sour taste. She can know that the way the apple appears to her now is vivid, pleasant, or like the way the orange appeared to her (namely, redly) yesterday in bad lighting. Finally, she has skill about her sensations. She can recall them to memory, reimage things in her mind, adjust her glasses until her sensations of color are vivid, and so forth.
Physicalists David Papineau and Paul Churchland have offered slightly different versions of the most prominent physicalist rejoinder to this argument: When Mary gains the ability to see red, she gains no knowledge of any new facts. Rather, she gains new abilities, new behavioral dispositions, new know-how, new ways to access the facts she already knew before gaining the ability to see. Before the experience, Mary knew all there was to know about the facts involved in what-it-is-like to experience red. She could third-person describe what it would be like for some other person to experience red. She could know what it is like to have an experience of red due to the fact that this is simply a physical state of the brain and Mary had mastered the relevant physical theory before gaining sight. But now she has a prelinguistic representation of redness, a first-person ability to image redness or re-create the experience of redness in her memory. She can re-identify her experience of red and classify it according to the type of experience it is by a new inner power of introspection. Prior to the experience, she could merely recognize when someone else was experiencing red “from the outside,” that is, from observing the behaviors of others. Thus the physicalist admits a duality of types of knowledge but not a duality of facts that are known.
For three reasons, this response is inadequate. First, it is simply not true that Mary gains a new way of knowing what she already knew instead of gaining knowledge of a new set of facts. Above, there are listed some aspects of Mary’s new factual knowledge, and it seems obvious that Mary failed to have this factual knowledge prior to gaining the ability to see.
Second, to be at all plausible, this physicalist rejoinder seems to presuppose a course-grained theory of properties according to which two properties are identical just in case they are either contingently or necessarily coexemplified. (For a property like being red to be exemplified is just for something, e.g., an apple, to have that property; for two properties to be coexemplified is for them to be jointly possessed by an object.) This assumption allows the physicalist to identify the relevant property in the knowledge argument (being red, being an-appearing-of-red) with a property employed in physical theory isomorphic with it (being brain state A). According to the course-grained theory, if being an-appearing-of-red and being brain state A occur together, they are really just the same property. But the course-grained theory is false. Being triangular and being trilateral are different properties even though necessarily coexemplified. The same may be said of various unexemplified (e.g., being a unicorn, being a Vulcan) or unexemplifiable (e.g., being a square circle, being a four-sided triangle) properties. These properties (e.g., being a unicorn, being a Vulcan) are possessed by the same objects, namely, no objects at all (!), yet they are not thereby the same properties as the course-grained theory implies.
Third, when Churchland and Papineau describe Mary’s new know-how, they help themselves to a number of notions that clearly seem to be dualist. They are listed in italics above: prelinguistic representation, image, first-person introspection, and so forth. These dualist notions are the real intuition pumps for the physicalist rejoinder. Remove the dualist language and replace it with notions that can be captured in physicalist language, and the physicalist response becomes implausible.
4.3 Consciousness and Intentionality
The third argument for property/event dualism is based on intentionality: some (perhaps all) mental states have intentionality. No physical state has intentionality. Therefore (at least) some mental states are not physical. Intentionality is the “ofness” or “aboutness” of various mental states. Consider the following facts about intentionality:
Many physicalists, especially functionalists, try to reduce intentionality to physical causal/functional relations. Functionalists describe mental properties/states in terms of bodily inputs, behavioral outputs, and other mental state outputs. For example, a pain is whatever state is produced by pin sticks and so on, and which causes a tendency to grimace and desire pity. The state of desiring pity is, in turn, spelled out in terms of other mental states and bodily outputs. Mental properties are functional kinds. A pain is not a state with a certain intrinsic quality, namely, hurtfulness; rather, it is a function an organism performs. Thus a completely inanimate computer can be “conscious,” say, have a thought or be in pain, if it performs the right outputs (produces “Ouch!” given the correct inputs, e.g., a pin stick).
Dualists respond by offering thought experiments in which causal/functional relations are not the same thing as intentionality. An example of this response comes from John Searle and is known as the Chinese room:
Imagine that you are locked in a room, and in this room are several baskets full of Chinese symbols. Imagine that you (like me) do not understand a word of Chinese, but that you are given a rule book in English for manipulating the Chinese symbols. The rules specify the manipulations of symbols purely formally, in terms of their syntax, not their semantics. So the rule might say: “Take a squiggle-squiggle out of basket number one and put it next to a squoggle-squoggle sign from basket number two.” Now suppose that some other Chinese symbols are passed into the room, and that you are given further rules for passing back Chinese symbols out of the room. Suppose that unknown to you the symbols passed into the room are called “questions” by the people outside the room, and the symbols you pass back out of the room are called “answers to the questions.” Suppose, furthermore, that the programmers are so good at designing the programs and that you are so good at manipulating the symbols, that very soon your answers are indistinguishable from those of a native Chinese speaker. There you are locked in your room shuffling your Chinese symbols and passing out Chinese symbols in response to incoming Chinese symbols. . . . Now the point of the story is simply this: by virtue of implementing a formal computer program from the point of view of an outside observer, you behave exactly as if you understood Chinese, but all the same you don’t understand a word of Chinese.
The Chinese room with the person inside would simulate a computer to an outside person and represents a functionalist account of mental states like thinking and understanding meaning. For a person outside, the room receives input and gives output in a way that makes it appear that the room understands Chinese. But of course, all the room does is imitate mental understanding, it does not possess it. Computers are just like the Chinese room. They imitate mental operations, but they do not really exemplify them.
We have seen reasons to affirm property dualism: consciousness and conscious states are mental and not physical. We now turn to an examination of some central arguments against property dualism—the view that conscious properties and events are not physical.
5—Arguments Against Dualism
A number of arguments have been raised against dualism. We will list three of them and offer brief responses.
5.1 The Problem of Interaction
1. Objection: Physicalists claim that on a dualist construal of a human being, mind and body are so different that it seems impossible to explain how and where the two different entities interact. How could a soul, totally lacking in any physical properties, cause things to happen to the body or vice versa? How can the soul move the arm? How can a pin-stick in the finger cause pain in the soul?
2. Response: This objection assumes that if we do not know how A causes B, then it is not reasonable to believe that A causes B, especially if A and B are different. But this assumption is not a good one. We often know that one thing causes another without having any idea of how causation takes place, even when the two items are different. Even if one is not a theist, it is not inconceivable to believe it possible for God, if he exists, to create the world or to act in that world, even though God and the material universe are very different. A magnetic field can move a tack, gravity (construed as a force) can act on a planet millions of miles away, protons exert a repulsive force on each other, and so forth. In these examples, we know that one thing can causally interact with another thing, even though we may have no idea how such interaction takes place. Further, in each case the cause would seem to have a different nature from the effect—forces and fields versus solid, spatially located, particle-like entities.
In the case of mind and body, we are constantly aware of causation between them. Episodes in the body or brain (being stuck with a pin, having a head injury) can cause things in the soul (a feeling of pain, loss of memory), and the soul can cause things to happen in the body (worry can cause ulcers, one can freely and intentionally raise his arm). We have such overwhelming, direct evidence that causal interaction takes place that there is no sufficient reason to doubt it.
Furthermore, it may even be that a “how” question regarding the interaction between mind and body cannot arise. A question about how A causally interacts with B is a request for an intervening mechanism between A and B that can be described. One can ask how turning the key starts a car because there is an intermediate electrical system between the key and the car’s running engine that is the means by which turning the key causes the engine to start. The “how” question is a request to describe that intermediate mechanism. But the interaction between mind and body may, and most likely is, direct and immediate. There is no intervening mechanism, and thus a “how” question describing that mechanism does not even arise.
However, the objection from interaction may be getting at something else. The argument may be that if a mental state or conscious agent were, in fact, to act on the brain or body, that would involve the creation of energy interjected into the brain/body, and thus mental causation violates the first law of the conservation of mass/energy.
In response, we make three points. First, the first law is not a metaphysical principle that necessarily rules out the creation of new energy; it is a mere scientific, heuristic, guiding principle that is employed while one is doing science. Moreover, it applies only to closed systems, those not subject to outside influence. But it would be question-begging to assert that the brain/body is a closed system. The dualist holds that, in fact, the brain/body does receive causal input from mental entities that are outside the physical system. In this case, the scientific, heuristic principle, while accurate and helpful in studying most systems, is just not applicable to mental causal influence. Second, the energy created when a mental agent intervenes and changes the direction of the flow of brain events (that flow would have gone one way without the interjection of mental causality, but with that interjection, it flows in a different direction) may be so small as to be virtually undetectable. Suppose that all the potential energy contained in the water held back by the Hoover Dam could be released by flipping a switch that opens up the dam and releases the water. The energy involved in flipping the switch is miniscule compared to the vast amount of energy released by the corresponding torrent of water flow. It may be that mental action on the brain/body is like flipping the switch, and the main energy (like the flow of water) is the triggering of potential energy in the brain. If this were the case, the energy created by mental action would be very hard to detect. Third, the phenomenon of quantum entanglement shows that A and B can causally interact without the creation of new energy. Quantum entanglement occurs when two (or more) particles interact in such a way that properties like spin or momentum are correlated with each other. For example, if the spin of one particle is measured to be clockwise, then the spin of the other will be counterclockwise. It seems that the measurement of one particle causes the other particle to have certain features and not others. But often the two particles are too far away from each other for the entanglement to involve an exchange of energy. Here, causal influence does not involve an interjection of energy into the system, and it may well be that mental/physical causation is the same.
A final way of understanding the objection from interaction is the claim that mental causation violates the causal closure of the physical; namely, if one traces the causal antecedents of a caused physical event, one will never have to leave the level of the physical. Only the physical can cause the physical. Unfortunately, this principle is, again, not a metaphysical principle stipulating what can or cannot happen; it is a pragmatically useful guiding principle used in science that amounts to a helpful assumption most but not all of the time. And there is no empirical evidence for the principle if it is construed as one that cannot be violated. Thus there is no good reason to accept this principle when we are dealing with questions about mental/physical causation. Further, as we have seen, mental states are real. Given this, the closure principle implies that mental states are epiphenomenal—they are caused by the brain, but they, in turn, contribute no causal influence whatever. Mental states are free riders on the brain that don’t do anything. This would imply, for example, that a feeling of thirst does not cause one to get a drink; it is the brain state that causes one to get a drink. But this is just implausible. Moreover, epiphenomenalism seems to be self-refuting. It is the propositional claim that no propositional content in thoughts or beliefs ever do anything to change people’s minds. People do not accept certain propositions and reject others due to mental processes of reasoning; no, they are determined by nonrational, purely physical processes to do what they do. If this is true, then asserting epiphenomenalism to persuade others of its truth is pointless and self-refuting.
5.2 Dualism Is Inconsistent with Naturalistic Evolutionary Theory
1. Objection: It is well known that one of the driving forces behind physicalism is naturalistic evolutionary theory. Evolutionist Paul Churchland makes this claim:
The important point about the standard evolutionary story is that the human species and all of its features are the wholly physical outcome of a purely physical process. . . . If this is the correct account of our origins, then there seems neither need, nor room, to fit any nonphysical substances or properties into our theoretical account of ourselves. We are creatures of matter. And we should learn to live with that fact.
In other words, this objection claims the following: since humans are merely the result of an entirely physical process (the processes of evolutionary theory) working on wholly physical materials, then humans are wholly physical beings.
2. Response: Dualists could point out that this objection is clearly question-begging. To see this, note that the objection can be put into the modus ponens form (see chap. 2):
However, the dualist could adopt the modus tollens form of the argument:
In other words, the evolutionary argument begs the question against the dualist. If the evidence for dualism is good, then the modus tollens form of the argument should be embraced, not the modus ponens form.
Further, Churchland’s claim invites us to formulate an argument for God’s existence from the existence of consciousness:
It is not our purpose here to defend this argument. We simply point out that the argument against irreducible, genuinely mental entities from evolutionary naturalism can backfire by providing the context for a theistic argument from the existence of the mental.
5.3 Dualism Is Ruled Out by Ockham’s Razor
1. Objection: Ockham’s razor states that people should not multiply entities beyond what is needed to explain something. Given two explanations of the same thing, people should prefer the one that is simpler, that is, the one that uses the fewest number of entities or kinds of entities to explain the thing in question. Now physicalism is simpler than dualism because it postulates only one type of entity (matter) to explain a human being instead of two (matter and mind). Thus in keeping with the requirements of Ockham’s razor, physicalism is preferred to dualism.
2. Response: There are two main problems with the application of Ockham’s razor to the mind-body problem. First, if Ockham’s razor is understood to be the fairly obvious, commonsense principle that an explanation of a phenomenon should include only elements within it necessary to explain that phenomenon, then the principle is uncontroversial. But it becomes question-begging when applied to the debate about dualism. Why? Because the dualist cites several phenomena for which physicalism as a theory is inadequate.
Dualists can agree that one should not postulate dualism needlessly, but they insist that dualism is, in fact, needed to honestly and fairly explain important, uneliminable features of human beings. The real debate, then, is not about Ockham’s razor, but about the relative merits of dualism versus physicalism. Furthermore, if Ockham’s razor is used to place a burden of proof on the dualist, the following can be pointed out. In light of both first-person awareness of one’s own self and the self-presenting nature of my mental states—one’s knowledge of them is often incorrigible and one has private access to them, neither of which is true for physical states—one is more certain one has genuine mental states than one is about the claim that physicalism is true. So the burden of proof may very well be on the physicalist. Remember, Ockham’s razor is a tiebreaker. It is applicable only if the competing theories are equal on other grounds. But the dualist will deny this.
5.4 Neuroscientific Discoveries Make Dualism Highly Implausible
1. Objection: In one way or another, this scientific objection implies that scientific evidence makes dualism, while possible, quite unlikely. To cite one example, Nancey Murphy claims that physicalism is not primarily a philosophical thesis, but the core commitment of scientific research, for which there is ample evidence. This evidence consists in the fact that “biology, neuroscience, and cognitive science have provided accounts of the dependence on physical processes of specific faculties once attributed to the soul.” Dualism cannot be proved false—a dualist can always appeal to correlations or functional relations between soul and brain/body—but advances in science make it a view with little justification. According to Murphy, “Science has provided a massive amount of evidence suggesting that we need not postulate the existence of an entity such as a soul or mind in order to explain life and consciousness.”
2. Response: This objection is misguided in two ways. First, people do not postulate the existence of conscious states in order to provide an explanation of, say, one’s own behavior, a postulation that could be rejected when a better (physicalist) postulation becomes available. No, people are directly aware of the nature of their conscious states, and they simply report to others what they introspectively know. Moreover, the claim that neuroscience is the most relevant and authoritative field in dealing with mind-body issues is hard to substantiate. Examining the relevant arguments in this and the next chapter makes evident that science could not even formulate, much less resolve most of the issues. For example, even if certain mental states are dependent on specific regions of the brain (and there is evidence for dependency in the other direction as well), a dualist can explain the dependence as a form of correlation or causation, rather than as some sort of identity relation. Indeed, the central issues regarding the mind—what is a thought, feeling, or belief; what is that to which my self is identical—are basically commonsense and philosophical issues for which scientific discoveries are largely irrelevant. Science is helpful in answering questions about what factors in the brain and body generally hinder or cause mental states to obtain, but science is largely silent about the nature of mental properties/states.
To see this, consider the following: we have discovered that if a certain type of neuron—mirror neurons—are damaged, then one cannot feel empathy for another. How are we to understand this? To begin with, we need to get before our minds the notion of empirically equivalent theories. If two or more theories are empirically equivalent, then they are consistent with all and only the same set of empirical observations. Thus an appeal to empirical data cannot be made in favor of one such theory over the others. Three empirically equivalent solutions to the discovery of the function of mirror neurons come to mind: (1) strict physicalism (a feeling of empathy is identical to the firings of mirror neurons); (2) mere-property dualism (a feeling of empathy is an irreducible state of consciousness in the brain whose obtaining depends on the firing of mirror neurons); (3) substance dualism (a feeling of empathy is an irreducible state of consciousness in the soul whose obtaining depends [while embodied] on the firing of mirror neurons). Of these three, no empirical datum can pick which is correct, nor does an appeal to epistemic simplicity help. Epistemic simplicity is a tiebreaker, and the substance dualist will insist that the arguments and evidence for substance dualism are better than those for the other two options mentioned above.
We have looked at the mind-body problem regarding mental properties/states, and examined the nature of consciousness along with the arguments for and against its nonphysical nature. In the next chapter we will investigate substance dualism and its rivals.
Chapter Summary
The mind-body problem regarding mental properties/states involves two main issues: Is consciousness physical or genuinely mental? If the latter, how do they interact? Various versions of physicalism and property dualism are the two main rivals in this area of inquiry. What a physical entity is and the main dualist strategies for defending property/event dualism were clarified and presented.
Next, we looked at the definition of consciousness, analyzed its main characteristics, listed five different types of conscious states, and noted the difference between phenomenal and access consciousness.
The final two sections covered important arguments for property dualism followed by a presentation and response to the main arguments against it.
Checklist of Basic Terms and Concepts
access consciousness
act of will
belief
blind sight
causal closure of the physical
Chinese room
consciousness
desire
direct access
emergentism
empirically equivalent theories
epiphenomenal
epistemic authority
epistemic subjectivity
first law of the conservation of mass/energy
intentionality
interaction (mind/body)
knowledge argument
knowledge by acquaintance
know-how
mental property/state
mere-property dualism
mirror neurons
neuron
nonreductive physicalism
Ockham’s razor
ostensive definition
phenomenal consciousness
physicalism
point-of-view subjectivity
property dualism
propositional knowledge
quale (plural: qualia)
secondary quality
self-presenting property
sensation
strict physicalism
synapse
thought
quantum entanglement
what-it-is-like