Michael Pauen
Painless Pain
Property Dualism and the Causal Role of 
Phenomenal Consciousness 
Running Head: Painless Pain

PD Dr. Michael Pauen
Institut für Philosophie
Philipps-Universität Marburg
35032 Marburg
Tel. ++49 (7071)  369296
email: pauen@mailer.uni-marburg.de

Painless Pain
American Philosophical Quarterly 37, 2000 p. 51-64.
Property Dualism and the Causal Role of 
Phenomenal Consciousness
Some of the issues in the philosophy of mind that have recently attracted much attention are based on the assumption that a distinction between mental and neural properties can be made without a commitment to substance- or event-dualism. These properties may be instantiated by one single physical event and the distinction between them can be maintained even if it turns out that there are strict correlations between certain mental and neural properties. 
This distinction fits in well with some deeply rooted intuitions concerning the relation between mind and brain; it has motivated some of the famous thought experiments like those that underlie the “absent qualia” and the “inverted spectrum” argument, and it supports objections against neurophysiological reductionism. David Chalmers’s diagnosis of the “hard problem” of consciousness and—at least one interpretation of—the “explanatory gap argument,” established by Joseph Levine, seem to be based on this position, too. The distinction has been defended by physicalists but it has also found supporters among those who have their reservations against physicalism. Kripke has tried to illustrate the distinction between mental and neural properties: after creating the physical substrate of pain God had to do additional work in order to create the phenomenal experience itself. 
In what follows, I will argue that a central assumption of most adherents of this position is not defensible: Property dualists usually maintain that there is a lawful relationship between the mental and neural properties they distinguish. It will turn out, however, that this assumption is unwarranted. As a result, not only the causal relevance of mental properties for the explanation of external behavior is put in doubt. Even our ability to provide reliable verbal reports on our own phenomenal states, say pain-experiences or olfactory sensations, or to remember these states truthfully is jeopardized if we subscribe to property dualism. 
In section one, I will discuss terminological questions and the requirements for the distinction of mental and neural properties. Although there are two versions of property dualism, I will demonstrate in section two that only one of them is acceptable for materialist philosophers. This version is based on the assumption that mental and neural properties are lawfully related. In section three, I will introduce a thought experiment in order to demonstrate that this assumption is unwarranted. Finally, I will discuss possible objections and further implications, particularly for the “explanatory gap argument” and for the status of first person experience, in section four. 
I
Some clarifications concerning the terminology seem to be in place. In talking about “neural properties,” I will refer to any property of the brain that has a physical or physiological description, without committing myself to a particular scientific theory of the brain.  The minimal requirement for “physical” descriptions, in turn, will be that they are given from the third person perspective. Different observers may have equal access to the same physical event or property. “Mental” properties, by contrast, can be described directly only from the first person perspective. I have an access to my present feeling that is precluded to anyone else—although another person may have a different mode of access to the very same state. 
I will take phenomenal properties and particularly pain as paradigm cases of mental properties. I assume that the neurobiological basis of pain-episodes is constituted by AS-activity, where AS-activity is supposed to be a complex set of neural processes in different areas of the brain, particularly in the anterior cingulate cortex and the somatosensory cortex. The expression “pain event” is used as an ontologically neutral term for the instantiation of both pain-related neural and mental activities likewise; thus a “pain event” may have a mental and a neurophysiological description or just one of them. Finally, since descriptions are underdetermined by the events, objects, and properties they refer to, different descriptions can refer to a single object or—as matters stand—to a single property. 
Property dualists usually agree that there is at least a theoretical chance that mental and neural properties may be instantiated separately. Thus, a distinction of a mental property P and a neural property N would require that there is a possible world where an object that instantiates the neural property N at time t does not instantiate the mental property P at t. It should be clear that even a nomological connection leaves room for such a distinction between neural and mental properties, since the connection does not hold across all possible worlds. 
II
Given these premises, property dualism has two alternatives. The stronger version would deny that there is, in fact, a lawful relation between mental and neural properties. This position doesn’t strike us as too attractive: the property dualist would have to admit that the relation between mental and neural properties is completely arbitrary. It would be possible at any time that a person is not conscious although she instantiates all the relevant neural properties. This violates the principle of “physical determination” which is essential especially for physicalists. According to this principle, physical facts determine all the positive facts about our world. But if mental properties can vary without a variation of neural properties, then there would be facts about the world, namely mental facts, that are not determined by physical facts. 
Since many property dualists regard themselves as physicalists, the weaker version of this position seems to be more attractive. In this case, a nomological connection would be accepted, thus it would be assumed that there is an empirically observable, lawful relation between mental and neural properties, a “psycho-physical law.” As a result, the physical determination requirement would be met. Chalmers, for instance, believes that “there appears to be a systematic dependence of conscious experience on physical structure in the cases with which we are familiar.” Nevertheless, the above requirement for property distinction is met; it is conceded that there might have been no lawful relation between mental and neural properties. Chalmers admits the logical possibility of a world that, although physically identical to our world, does not instantiate consciousness. Similar statements can be found in Kripke or Levine. However, our empirical observations show that this lawful relation holds in our world. As far as we know to date, mental properties are “realized” by certain neural properties, or they supervene on them. 
Unlike the identity theory, property dualism assumes that the causal roles of both properties differ. According to the majority of the proponents of this position, only the neural, but not the mental properties are causally relevant. This assumption is essential especially for physicalists. They would violate the principle of “causal closure” if they were to grant mental, i. e. non-physical properties an independent causal role. But even those who do not regard themselves as dyed-in-the-wool physicalists should be wary of assigning independent causal powers to mental properties since this would lead directly to an interactionist dualism. 
It would follow that, strictly speaking, the neural processes subsequent to a pain event depend only on the neural properties of this event, not on its mental properties. Language-related activity in the brain that is caused by AS-activity and leads to a pain statement can serve as an example. If mental properties do no causal work then the activity in the language system might have occurred even if no phenomenal pain had accompanied the AS-activity. This case, however, appears as a purely theoretical proviso since our empirical knowledge tells us that mental and neural properties are lawfully related, at least in humans. 

But let’s go a bit more into the details of the “weak” version of property dualism. Suppose, we have a pain event E1, with a phenomenal property P1 (pain), and a neural property N1 (AS-activity), and, in addition, we have E2, a subsequent language-related activity in our brain that leads to a verbal expression of pain. In this case, the following would hold under the above premises: 

(1) 	E2 would not have happened if E1 had not instantiated property N1. 

The following, however, would not hold:

(2) 	E2 would not have happened if E1 had not instantiated property P1. 

The consequences of a rejection of (2) don’t appear too serious: after all, the property dualist can refer to the psycho-physical law that connects N1 and P1. If this law holds, then E1 will not instantiate N1  without instantiating P1 at the same time: AS-activity won’t occur in the absence of pain. Therefore, we can be sure that E2 will not happen if E1 does not instantiate P1—as long as the law holds. Note however, that even this law would not establish an immediate dependence of E2 upon P1; it establishes only an additional dependence of P1 upon N1. Thus, the law does not govern the consequences that would follow if E1, for whatever reason, would instantiate N1 but not P1: if something like this would happen, then E2 would still follow. The law says only that a dissociation of N1 and P1 will not occur in our world. 
Still, this law is of central importance for property dualism because it warrants scientific access to mental properties under the premises of this theory. Since we have no direct access to the mental states of test persons in our experiments, we must rely on verbal statements or on nonverbal behavior which, in turn, depend on events like E2, say language-related activity in Broca’s  and Wernicke’s area. Since these events are caused by the neural properties of pain events only, verbal statements about pain can be regarded as reliable indications of mental properties only if the psycho-physical law holds. Otherwise, these statements might occur also in the absence of phenomenal  pain, due to AS-activity only. 
It should be noted that the identity theory gets along without such a law. It can rely on verbal statements because mental properties, due to their identity with neural properties, are among the causes of these statements, likewise of self reports, pain behavior, etc. Thus, identity theorists get the mental properties “for free” as soon as they have determined the relevant physical properties. Property dualists have to do more work: they must establish the psycho-physical law.
III
In what follows, I would like to ask how the property dualist can establish this law on the basis of empirical knowledge. Like any empirical test that is supposed to yield evidence in support of a law or a hypothesis in general, the procedure in question should be able, in principle, to provide evidence against the hypothesis, should the hypothesis be wrong. Take an example from physics: empirical observations of stones falling down to earth provide some initial evidence for the law of falling bodies only because we have reason to believe that the same type of observation would enable us to detect it if stones would start to move upward. The same must be true for an empirical test of the psycho-physical law: we must make sure that we would detect a violation of this law, should such a violation occur. Note that, at this point, we cannot rule out such a violation with reference to the psycho-physical law because what’s at stake is the empirical basis of this very law. 
Many property dualists seem to suppose that the usual correlation studies can serve to establish the psycho-physical law. But do studies of this type meet the above requirement? In order to answer this question, it is necessary to find out what would happen if AS-activity would occur in the absence of phenomenal pain. 

(3) 	Suppose, two persons, A and B, instantiate the same neural properties at time t. Only A instantiates also a certain phenomenal property. AS-activity is identical, but at time t only A experiences a sharp pain which is not felt by B. For reasons of simplicity, let’s assume that B, too, usually has mental states as well: she has episodic and semantic memories, she usually has phenomenal consciousness and she feels pain under normal circumstances. 

(4) 	Because both persons instantiate the same neural properties, there will be no difference between them as far as the physical processes are concerned that depend on these properties. Since, due to the causal closure, mental states are assumed to have no direct causal effects, the processes in B’s brain that occur subsequently to the AS-activity will not differ from the processes in A’s brain. 

As a consequence, A and B will not differ in their external behavior. Because the physiological processes in the brains of both persons are identical, A and B should not differ in their verbal statements either. Hence, both would probably try to get rid of the presumed cause of their suffering and both would tend to express their pain-experience verbally. An experimenter or another observer would therefore be unable to distinguish A and B. 
This outcome has serious consequences not only for this hypothetical situation, rather, it forces us to change our evaluation of the “real” empirical procedures that are thought to provide evidence in support of the psycho-physical law. If self-reports and pain behavior of our test subjects would not indicate a possible absence of the properties in question, then they cannot be taken to support the psycho-physical law because they do not meet the above requirement. 

It seems, however, that property dualism has another option. We could imagine that B herself realizes the absence of the phenomenal properties of the pain event and subsequently makes a verbal report. The difficulties concerning the causal relation between E1 and E2 will disappear, since B must have direct access to her actual or, for that matter, missing phenomenal experiences. The above requirement would be met, and as long as nobody reports dissociations of this type in experiments or in everyday life, the property dualist could conclude that they do not happen and that his lawful relation holds. 
On closer inspection, the problems recur. Given the causal inertness of mental properties, B’s missing phenomenal experience will not make any difference in her memory traces of the event in question, either. The encoding of suchlike traces is a physiological process which, according to property dualism, depends on the neural properties of the preceding memorized event only. The encoding of a memory trace of E1 would be an event like E2, and this event would not change if E1 had no properties like P1. Thus, the absence of mental properties would not affect the memory traces of an event as long as the event instantiates the relevant neural properties.
As a consequence, if B would try to remember the pain event later, her apparent memories would not differ from A’s memories. Hence, it would appear to her as if she had experienced pain at time t: her memory traces, after all, can not differ from the traces of A. B has to rely on her own memories, and if she is questioned afterwards, her answers will be subject to this “deception” too. Thus, this option doesn’t seem to be a solution for the property dualist’s problems either. 
Under the premises of property dualism, similar difficulties may become apparent whenever we remember our own phenomenal states. If I think back to an event like E1 that has happened to me some days ago, it would seem to me as if I would remember a painful event, even if the relevant phenomenal property was not instantiated at that time. The temporal distance between the pain event and our efforts to recall it may be very short, since short term memory, too, is causally related to the original events. So even if the painless pain event happened only seconds ago, I would not remember it as such. 
 But if these dissociations never turn up in our memories, it would follow that the property dualist cannot judge how widespread they actually are. Our phenomenal experience might be interrupted quite frequently, it would even be possible that all my present memories refer to phenomenal states that I have never experienced directly. Hence, the claim that dissociations happen only in exceptional cases would also be unwarranted. 

However, at least one response seems to be left to property dualists: they could refer to the existence of phenomenal states in their own present experience and could carry out the famous autocerebroscope-experiment in order to verify the presence of the relevant neural properties.
Serious objections can be raised against such an undertaking. Apart from problems pertaining to the autocerebroscope-experiment itself, authors such as Dennett/Kinsbourne (1992) and Metzinger (1993, 102) have argued that mental states, although they appear to be directly present in the first person perspective, are in fact intricate constructive processes that may extend over a considerable period of time. As Pöppel has demonstrated, this process requires memory activities that cover a period of some three seconds. Although I accept these objections, I will leave them aside for the sake of the argument because I would like to give some further clarification on the problems of property dualism. 
So, suppose we were able to observe AS-activity in an autocerebroscope exactly in parallel with our phenomenal experience of pain. It seems that the above difficulties could be sidestepped: since we are talking only about those phenomenal states we have immediate access to, no “deception” due to memory encoding or other causal processes can occur. 
Imagine then, I would be B at time t. The autocerebroscope right before me indicates heavy AS-activity, I show the avoidance-behavior which is characteristic for someone who experiences a sharp pain, but as in the case of B, the phenomenal properties are absent although I’m conscious. It seems obvious that I should be seriously irritated, I should start to argue with the experimenter, complain about the bad autocerebroscope, etc. 
I’m perfectly  sure, in fact, that this is what I would do, should something similar happen to me, but, given the premises of property dualism, I could not do so. Again, if only neural properties are causally efficacious, then the absence of the matching phenomenal properties can’t affect my behavior and, what is more, it can’t even affect the subsequent mental processes. This does not only mean that I will be unable to report or remember these dissociations; if the above premises hold and if cognitive processes cannot occur without underlying neural processes, then I couldn’t even think about the dissociation between experience and behavior, since the absence of phenomenal properties would have no effect on those neural processes that are the basis of my thoughts. As soon as the dissociation is over, everything will be as if it never happened: I won’t remember the painless pain and I won’t even ponder on these mysterious goings on. 
IV
It would seem, then, that this option doesn’t help property dualism out of its difficulties either. It is obviously impossible to find an empirical test that would detect a possible violation of the psycho-physical law. The outcome of the experiments above would not be affected if the hypothesis had been wrong, that is, if the psycho-physical law would not hold. As a consequence, the above requirement is not met. It is impossible to rule out that the presumed evidence came about in the absence of just those phenomenal properties it is intended to indicate. Of course, we could take our commonsense opinion about the relation between pain and AS-activity for granted and rule out any dissociation by fiat. This move, however, would violate the basic rules of empirical hypothesis-testing. 
Since it is impossible to establish the desired lawful relation between mental and neural properties, property dualism can’t be restricted to the weaker version of this account. If the psycho-physical law can not be established, then the difference between both versions of property dualism collapses, since this difference depends upon the nomological connection between mental and neural properties. Moreover, since, on this account, the neural or, for that matter, the physical facts do not determine the phenomenal facts, the principle of physical determination is also violated.
I would like to emphasize the difference between these objections and a skeptic position: unlike skeptic scenarios, the thought experiments above agree completely with our scientific or folk knowledge except, of course, the psycho-physical law. Skepticism, by contrast, contradicts physics as well as our folk theories because it assumes that these theories talk about a world that does not exist—or did not exist five minutes ago. Because of this fundamental difference, the adherent of property dualism won’t get rid of the above objections just by pointing out that nobody believes in skepticism although we can’t disprove it formally. 

Property dualism shouldn’t strike us, therefore, as a very attractive account in the philosophy of mind. But do the considerations above really disprove the basic assumptions of this position? After all, my arguments referred to epistemic problems, namely difficulties in our access to mental properties. It is unclear, however, whether these difficulties amount to a serious ontological argument against the distinction of mental and neural properties. Imagine—as is still conceivable—it would be true that causally inert mental properties exist: should this truth be put in doubt just because we are unable to establish it empirically? 
I agree that property dualism is a logical possibility, thus, it might be an ontological truth that causally inert mental properties exist apart from any physical properties. However, two principal objections that follow from the considerations above make it doubtful whether it is reasonable to subscribe to such an ontology. First, contrary to one of the central claims of the “weak” and most popular variety of property dualism, there is no empirically observable “systematic dependence of conscious experience on physical structure” (Chalmers). The second reason why I doubt that this is a reasonable ontological position is based on the assumption that ontology has to make sense of our empirical knowledge about the world. So, if it turns out that there are strict and specific correlations between reports on phenomenal pain and AS-activity, we could still insist on the distinction between neural and mental properties, we could also continue to believe that our verbal and nonverbal behavior as well as our thoughts and memories about phenomenal states are determined only by neural properties, and we could, finally, stick to the belief that phenomenal properties are causally inert and make no difference to the physical world. However, the above arguments demonstrate that such an ontology would fail to make sense of our empirical knowledge: Of course, property dualism offers explanations. But, as we have seen above these explanations would force us to believe that phenomenal properties are not among the causes why we talk about them, remember them, think about them, or, as the case may be, write papers on them. Therefore, this ontology would not help us to understand why we do so, that is, it would fail to make sense of these facts. 
That’s why the above considerations should lead us to a different result, namely to the conclusion that mental properties are causally relevant. It should be noted that this implies not only some sort of causal relevance in general, rather, it implies specific causal relevance. Differences at the phenomenal level must be paralleled by causal differences: If the causal role of a certain pain experience would not differ from the causal role of an experience of joy, both types of experiences would affect behaviour and memory in exactly the same way. As a consequence, we could not distinguish these types of pain and joy in memory and behavior, thus we might remember an episode of joy as an episode of pain or vice versa. 
As long as we want to avoid interactionist dualism, the identification of mental and neural properties seems the best way to do justice to these considerations. In this case, mental properties would be regarded as causally efficacious due to their identity with causally efficacious physical properties. 

This leads me to some—admittedly very sketchy—remarks that should indicate how the above results fit into the present discussion. I am not going to argue for a specific position, but rather, I will try to outline the consequences, that the above considerations have for the debate on the explanatory gap argument and, particularly, for the scientific status of first person experience. 
According to property dualism, phenomenal properties can be regarded as something ‘over and above’ the physical features of the world. Being causally inert, these states can not be accounted for by science because they are not susceptible to the usual explanations in terms of causes and effects: That’s the bottom-line of the explanatory gap argument. At the same time, one may argue that phenomenal states need not be accounted for because they do not interact with the objects of scientific study.
But this separation of physical processes and phenomenal states, plausible as it may appear at the face of it, is put in doubt by the results of the present study. If phenomenal properties are causally efficacious, they will interact with other entities, so we have to take them into account in some way or other. It might seem, however, that the identity theory can achieve this very easily, provided that we are able to account for neural states. If a phenomenal state is identical with a neural state then, due to the substitutivity of identity relations, every valid explanation of the neural state has to be counted as a valid explanation of the corresponding (i. e. identical) mental state as well—after all, the mental state is the neural state. 
One might conclude that this would solve the explanatory gap problem, but unfortunately, the argument has a severe drawback: if the identity claim implies the transfer of neurophysiological explanations to the corresponding mental states, then doubts that neurophysiological explanations actually apply to mental states are ipso facto doubts that the identity claim is true. Those doubts have persisted so far: knowledge about the emergence of AS-activity doesn’t seem to help us very much if we want to understand why pains feel the way they do. Thus, the identity claim can be challenged as long as it remains unclear how to use knowledge about the emergence of AS-activity in order to answer questions about the emergence of pain. 
It should be obvious, however, that the problem now has shifted to the epistemic level. Under the premises of the identity theory the question is not: “How do we explain the relation between mental and neural properties?” Rather, the question would be: “What is the relation between neurobiological theories about AS-activity and psychological or first person knowledge about pain?” This is exactly where the first person experience comes in: a precise description of the relevant phenomenal states is one of the most important prerequisites for a solution of this problem. In fact, it is widely accepted that the problem could be solved if we could capture phenomenal properties in terms of their causes and effects. 
It has been vigorously denied that suchlike descriptions are possible. I agree that any effort to provide such a description may fail. But if, as the considerations above seem to indicate,  phenomenal properties actually have causal powers that reflect their first person qualities in some way or other, then we can’t rule it out that this connection may be sooner or later discovered by scientific research. Thus, it seems that we can account for phenomenal states as well—at least in principle. 
It is beyond the scope of this paper to determine whether this theoretical possibility can be turned into a promising strategy. However, two observations might be in place here. First, it should be noted that our vernacular concepts of emotions already have certain functional implications. This becomes obvious if we try to use these words in a way that contradicts those implications. Take the word “disgust.” It doesn’t make sense to say that it was a feeling of disgust—and not a secondary purpose—that caused us to reach out for an object. Conversely, we would say that someone who claims that his desire has motivated him to avoid the desired object doesn’t know the meaning of this word. Second, several approaches in the psychology of emotion try to bring some systematicity into the seemingly chaotic realm of phenomenal experience. What is more, converging evidence indicates that we can refine, enrich, and correct our knowledge about the functional implications of emotions on a scientific basis. It has been forcefully argued by Damasio (1994), LeDoux (1996), Griffiths (1997), and others that bodily states and action tendencies are among the constituents of emotional states—not just among their effects or concomitants. 
Presently, the available functional descriptions of emotions are obviously insufficient and it is still uncertain whether they will ever be adequate. But if they can be improved significantly, then they might capture what we mean when we talk about a certain phenomenal state. In this case, they could serve as a basis for the desired transfer of explanations. Since the functional description would apply to the phenomenal and the neural level likewise, a physiological explanation of the neural processes that implement these functions could also be regarded as a plausible explanation of the identical phenomenal processes: after all, our descriptions of these processes refer to just those functional properties. Thus, the explanation in question would not only support the identity claim, it should also help us to understand the emergence of the phenomenal state, that is, it should explain why the instantiation of AS-activity leads to pain rather than joy or fear.
It is unclear whether we will ever arrive at this point. In any case, these considerations demonstrate that a careful examination of mental and particularly phenomenal states is a constitutive element of every serious philosophical effort to make progress on the problems of consciousness. While the identity hypothesis does provide a basis for such an examination, property dualism fails, because it sets first person experiences apart from the legitimate objects of scientific study and even jeopardizes the very existence of these experiences. Of course, many of us wouldn’t mind if pain became painless, but we certainly would not want to dismiss our phenomenal experiences altogether: colorless colors and mute sounds might become a bit boring in the long run.

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