Chapter 10 – p-Zombies

This chapter is about p-zombies: whether they are behaviorally and physically identical to human beings or not and whether, in reality, they can physically exist or not.

10.1. p–Zombie

A p-zombie (philosophical zombie) is generally defined as “a being that is physically identical to a normal human except that it lacks qualia and consciousness (conscious awareness and experience)” [1-16]. For example, when a p-zombie sees a red color, it will have unconscious perception of the red color: its brain will register the physical characteristics, such as the wavelength, the frequency, and the intensity, of the red color and will react to these physical characteristics, but all of these occur unconsciously, and, because the red color quale does not occur in its mind, the p-zombie will not have the conscious perception of the red color quale, i.e., it will not be consciously aware of and will not consciously experience what the red color quale is like in its mind. This is different from a normal human: the red color quale occurs in his/her mind, and, in addition to the unconscious perception of the red color, he/she will have the conscious perception of the red color quale, i.e., he/she will be consciously aware of and will consciously experience what the red color quale is like in his/her mind.

However, although the above definition is philosophically possible, it is not certain that it is physically tenable. This is because, if qualia and consciousness have physical effects, these physical effects will not exist in the p-zombie, who lacks qualia and consciousness, while these physical effects will exist in the human, who has qualia and consciousness; the lack of these physical effects will make the p-zombie physically different from the human and make the definition’s clause “physically identical to a normal human except that it lacks qualia and consciousness” impossible to be true physically. This problem will become obvious if we consider this definition in the form of equations:

A human = a being with qualia and consciousness and their effects … (1)

A p–zombie (philosophical definition) = A human – qualia – consciousness

 = a being without qualia and consciousness but with their effects … (2)

Thus, if qualia’s and consciousness’s effects exist, Equation (2) will define a being that is impossible to exist physically because qualia’s and consciousness’s effects cannot occur without qualia and consciousness. And comparing a human with an entity that may not exist physically will have no definite conclusion in the physical world. Therefore, if we want to do an experiment to see whether, physically, a being with qualia and consciousness and a being without them are behaviorally identical or not, we must use the definition that all the beings in the experiment can definitely exist physically. In doing so, we must take the possibility that qualia and consciousness may have physical effects into account. Thus, the appropriate definition must instead be a p-zombie is “a being that is physically identical to a normal human except that it lacks qualia and consciousness and their effects”, as in the following equation:

A p–zombie (physical definition) = A human – qualia – consciousness – their effects

= a being without qualia and consciousness and their effects … (3)

Whether qualia’s and conscious experiences’ effects exist or not is to be proved by separate investigations.

This is similar to the scenario that we define that a p-zombie is “a being that is physically identical to a normal human except that it lacks the pineal gland”. Again, although this definition is imaginarily possible, it is not physically possible. Because the pineal gland has a hormone and its physical effects, if the being lacks the pineal gland, it will lack the pineal gland hormone and its physical effects; while the human, with the pineal gland inside, still has the pineal gland hormone and its physical effects. The lack of the hormone and the physical effects will make the p-zombie physically different from the human and make the definitions’s clause “physically identical to a normal human except that it lacks the pineal gland” impossible to be true physically. The definition that is physically applicable has to be a p-zombie is “a being that is physically identical to a normal human except that it lacks the pineal gland and pineal gland’s effects”. These definitions can be summarized as the following equations (in which “pineal gland’s effects” stands for “pineal gland hormone and its physical effects”):

A human = a being with the pineal gland and pineal gland’s effects … (1)

A p–zombie (imaginary definition) =A human – pineal gland =

a being without the pineal gland but with pineal gland’s effects … (2)

(physically impossible, pineal gland’s effects cannot occur without the pineal gland)

A p–zombie (physical definition) =A human – pineal gland – pineal gland’s effects =

a being without the pineal gland and pineal gland’s effects … (3)

(physically possible)

From the definitions, a human (1) and a p-zombie (imaginary definition) (2) are different in only that the human has the pineal gland while the p-zombie does not. Everything else, including the pineal gland hormone and its effects (on behavior, other biological activities, and other things) in the p-zombie, who has no pineal gland, is the same. So, if we compare the two beings, we will find that they behave identically, and the conclusion will be that the world of p-zombies and the world of humans are behaviorally identical*. However, this conclusion is valid only imaginarily but not physically because a p-zombie as defined by the imaginary definition is physically impossible. Such a p-zombie cannot really exist, and neither can the world of such p-zombies. So, the conclusion that the world of p-zombies and the world of humans are behaviorally identical must be treated as an imaginary conclusion – this conclusion is not physically valid and is irrelevant to the real world.

(* Although this cannot be true in the present world due to advanced medical technology [such as MRI, CT scan, brain autopsy, or brain surgery] that can reveal the absence of the pineal gland and differentiate a p-zombie from a human, it could be true in the primitive world because, due to the lack of advanced medical technology, the lack of the pineal gland in the p-zombies would have been unnoticeable and thus virtually without physical consequences.)

On the other hand, from the definitions, a human (1) and a p-zombie (physical definition) (3) are different in that the human has the pineal gland and its effects while the p-zombie lacks both of them. Even if we grant that just the lack of the concealed tiny pineal gland in the head does not have any physical effects, the pineal gland hormone and its physical effects have significant physical effects that cannot be assumed to be null, and the lack of them definitely has physical consequences. So, if we compare the two beings, we will find that they behave differently, and the conclusion will be that the world of p-zombies and that of humans are behaviorally different. This conclusion is physically valid and is relevant to the real world.

In the case of qualia and consciousness, everything is similar. Let’s investigate the case of qualia first.

A human = a being with qualia and qualia’s effects(1)

A p–zombie (philosophical definition) = A human – qualia

= a being without qualia but with qualia’s effects … (2)

(physically impossible if qualia’s effects do exist; they cannot occur without qualia)

A p–zombie (physical definition) = A human – qualia – qualia effects

= a being without qualia and qualia’s effects … (3)

(physically possible)

From the definitions, a human (1) and a p-zombie (philosophical definition) (2) are different in only that the human has qualia while the p-zombie does not. Everything else, including the qualia’s effects (on behavior, other biological activities, and other things) in the p-zombie, who does not have qualia, is the same. So, if we compare the two beings, we will find that they behave identically, and the conclusion will be that the world of p-zombies and the world of humans are behaviorally identical. However, although this is a philosophically valid conclusion, it is not certain that it is a physically valid conclusion. If qualia’s effects do exist, a p-zombie defined by this philosophical definition will be physically impossible to exist (because qualia’s effects without qualia are not physically possible). This conclusion, which may involve an impossible physical entity, thus may be physically invalid.

On the other hand, from the definitions, a human (1) and a p-zombie (physical definition) (3) are different in that the human has qualia and their effects while the p-zombie lacks both of them. If qualia’s physical effects exist, they will occur in the human, but not in the p-zombie; therefore, the p-zombie, who lacks qualia’s effects, will behave differently from the human, who has qualia’s effects. So, if we compare the two beings, we will find that they behave identically if qualia’s effects do not exist but will find that they behave differently if qualia’s effects do exist.  So, whether the p-zombies behave differently from the humans and whether the world of p-zombies is behaviorally different from that of humans depend on whether qualia’s effects exist or not. This will be discussed later.

The comparisons are the same in the case of consciousness. Just replace qualia in the previous equations with consciousness.

At this point, it should be noted that one may believe and assert that qualia and consciousness do not have any physical effects, so they can be compared by using the philosophical definition, and the result will also be valid physically. However, using an inappropriate definition is not a correct way of doing a scientific experiment, even if it is a thought one, and can lead to confusion and misconception. Also, if one is committed to the belief that qualia and consciousness do not have any physical effects, then it is no use making the physical comparison between the human and the p-zombie – they are physically identical by the definition and the belief already. Because, by the definition, the difference between the human and the p-zombie is qualia and consciousness, if qualia and consciousness do not have any physical effects, then the difference between the human and the p-zombie does not have any physical effects. That is, the difference between the human and the p-zombie is physically null, and the human and the p-zombie, with no physical difference, are physically identical. Stating in equations:

A humana p-zombie = qualia and consciousness (by the definition) … (1)

Qualia and consciousness = no physical effects (by the belief) … (2)

A humana p-zombie = no physical effects … from (1) & (2)

A humana p-zombie = 0 (physically)

A human = a p-zombie (physically)

Thus, by the definition and the belief, a human and a p-zombie are already physically identical, and there is no use in doing thought experiments examining physical differences between physically identical entities. This is like comparing an ordinary computer with an n-computer, which is a computer with a name (e.g., Alice, Bob, or Charlie) called by a human but not registered in the computer’s system. Because such names do not have any physical effects on computer functions, ordinary computers and n-computers will function identically, and the world of ordinary computers and that of n-computers will be physically identical. Undoubtedly, everyone knows that they are physically identical entities, and no one will spend time doing thought experiments examining physical differences between them. But do qualia not have physical effects on humans as names do not have physical effects on computers?

Actually, this problem has been discussed in detail in Chapter 5 and 6, and it has been proven that qualia and consciousness have physical effects (section 5.4 and 6.4). This is simply because both qualia and consciousness induce the brain to create conscious awareness and conscious experiences of themselves (this is evident by the fact that we do have conscious awareness and conscious experiences of both the qualia and our consciousness). Because conscious awareness and conscious experiences in the brain require specific neural processes to occur to function accordingly, qualia and consciousness induce the occurrences of specific neural processes. And because neural processes are physical processes, qualia and consciousness induce the occurrences of physical processes. They thus have physical effects. And these physical effects are the physical effects that are to occur, at the minimum. (See the summary of this matter in the next section.)

Qualia    occurrence of conscious awareness and experiences of the qualia

Consciousness    occurrence of conscious awareness and experience of the consciousness

Thus, qualia and consciousness to humans are not like names to computers, and the above belief (that qualia and consciousness do not have any physical effects) is not correct. Therefore, the philosophical definition is not physically tenable, and the result of thought experiments using philosophical definition is not physically valid.

In conclusion, we have to be careful how we define entities. If we define them philosophically or imaginarily, although such defined beings can exist in those realms, in some cases, such as the p-zombie cases above, they cannot exist in the physical realm, which is the real-life world. And the experiment conclusions pertaining to those definitions in such cases will be valid only imaginarily. Such conclusions are irrelevant to the real-life world. But if we define them physically, all the entities will exist in the physical realm, which is the real-life world. And the experiment conclusions pertaining to the physical definition will be valid physically. Such conclusions are relevant to the real-life world.

Now, let’s compare a human with a p-zombie (physical definition) to see their differences. Consider what happens in a human and a p-zombie when they see a tiger (Figure 10.1).

Figure 10.1 Human’s perception vs. p-Zombie’s perception

The early neural events in their visual pathways from the eyes to the cortical areas just prior to the cortical areas for perception are exactly the same. But once perception areas begin to function, further events are different. In the p-zombie, there will be a visual perception of the tiger, but this occurs without a quale, conscious awareness, and conscious experience, like an image registration in the motherboard of a present-day computer. In the human, in addition to the perception like the one that happens in the p-zombie, a visual quale of a tiger occurs. Subsequently, conscious awareness (C.A.) and a conscious experience (C.E.) of the quale occur in his mind. And, subsequently to this, conscious awareness and a conscious experience of the conscious awareness and the conscious experience of the quale also occur. Therefore, there are neural processes that function to create these conscious awareness and conscious experiences occurring in the human, while there are no such neural processes occurring in the p-zombie. The brain of the human and that of the p-zombie, having different neural processes, are thus in different physical states and therefore function differently. The additional neural processes that function to create conscious awareness and conscious experiences, being physical processes, must have some physical effects that do not occur in the p-zombie: they may cause more intense fear, more alertness, more sympathetic stimulation, etc., and additional and/or different behaviors will occur in the human. Thus, the human is physically and behaviorally different from the p-zombie. The world of p-zombies is, therefore, physically and behaviorally different from that of humans. And it can be concluded generally that a world with no qualia and consciousness is physically and behaviorally different from a world with qualia and consciousness.

This can be more obvious if we consider this matter in the opposite way. A present-day computer does certainly not have conscious awareness and a conscious experience of any quale that may occur in it because there are no circuits built to do these specific functions. Conscious awareness and a conscious experience of a quale are additional functions with additional information, and a computer needs additional circuits to manage them. Therefore, all functions else being the same, a computer that can function to have conscious awareness and experiences of qualia must have additional circuits and will thus be physically and functionally different from computers that cannot function to have conscious awareness and experiences of qualia.

10.2. Effects of qualia and consciousness

* The awareness and experiences of what the phenomenal characteristics are like occur in IVb and Vb.

Now, let’s summarize how qualia and consciousness can have effects in the nervous system.

1. Suppose there are visual stimuli from the outside world entering into the central nervous system of a zombie and a human.

2. Unconscious visual perceptions (II) occur similarly in both the zombie and the human. Their effects are the same in both beings at this level. If the zombie does not have qualia and consciousness, these unconscious visual perceptions will be the only kind of perceptions that occur in the zombie and that have effects in the nervous system.

3. But if some advanced zombies have visual qualia (III) occurring but still do not have conscious awareness and experiences of what the phenomenal characteristics of the visual qualia are like occurring (i.e., still do not have consciousness), only visual qualia (III) and unconscious perceptions of visual qualia (by some sub-conscious neural processes) (IVa) will occur in them (in addition to II above).

4. In the human, in addition to unconscious visual perception (II), visual qualia (III), and unconscious perceptions of visual qualia (IVa), conscious perceptions of visual qualia (IVb) occur. Moreover, unconscious perceptions of IVb (Va) and conscious perceptions of IVb (Vb) also occur. These are phenomena that do not occur in the zombie who has neither qualia nor conscious awareness and experiences of qualia, and the effects of these phenomena do not occur in the zombie.

5. Because qualia (III) induce the occurrences of conscious perceptions of themselves (IVb) and because conscious perceptions require specific neural processes, qualia induce the occurrences of physical processes. Qualia thus have physical effects.

6. Likewise, the conscious perceptions of qualia (IVb) induce the occurrences of conscious perceptions of themselves (Vb) and because conscious perceptions require specific neural processes, the conscious perceptions of qualia (IVb) induce the occurrences of physical processes. They thus have physical effects. That is, the conscious perceptions (conscious awareness and experiences of what the phenomenal characteristics are like) have physical effects – the consciousness itself has physical effects.

7. Other effects are also possible theoretically, such as effects from unconscious perceptions in IVa and Va by some sub-conscious neural processes, but there is no definite evidence for them yet.

In summary, qualia and consciousness have effects on the brain because they induce conscious perceptions of themselves in the brain. Because conscious perceptions require specific neural processes and because neural processes are physical processes, qualia and consciousness induce the occurrences of physical processes – qualia and consciousness thus have physical effects. And they are physical effects that are to occur at the minimum – other effects from sub-conscious neural processes that are affected by qualia and consciousness are also possible. Because qualia and consciousness have physical effects, the philosophical definition of a p-zombie is physically invalid because the definition does not take their physical effects into account.

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References

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Keywords: p-zombie, philosophical zombie, lying zombie, confabulating zombie

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