Consciousness

Rocco J Gennaro, Rocco Gennaro

• Publisher: Routledge
• Year: 2016
• Print ISBN: 9781138827707
• eBook ISBN: 9781315521510
• Topic: Philosophy
• Subtopic: Philosophy History & Theory

Consciousness is arguably the most important interdisciplinary area in contemporary philosophy of mind, with an explosion of research over the past thirty years from philosophers, psychologists, and scientists. It is also perhaps the most puzzling aspect of the world despite the fact that it is familiar to each of us. Consciousness also seems resistant to any straightforward physical explanation.

This book introduces readers to the contemporary problem of consciousness, providing a clear introduction to the overall landscape and a fair-minded critical survey of various theories of consciousness. Beginning with essential historical background to the problem of consciousness, Rocco Gennaro explores the following key topics and debates:

• the metaphysical problem of consciousness, including varieties of dualism and materialism;
• consciousness and neuroscience, particularly the question of whether consciousness can be reduced to brain activity or attentional mechanisms;
• representational and cognitive theories of consciousness;
• consciousness and psychopathology;
• animals, machines, and consciousness.

Extensive use is made of interesting phenomena throughout the book, ranging from blindsight, synaesthesia, and change blindness to phantom limb syndrome, split-brain cases, and dissociative identity disorder (DID).

The inclusion of chapter summaries, annotated further reading, and a glossary make this book essential reading for anyone seeking a clear and informative overview of the problem of consciousness, not only in philosophy but related fields such as psychology and cognitive science.

1

THE METAPHYSICS OF CONSCIOUSNESS

1.1 Dualism and materialism

Metaphysics is the branch of philosophy concerned with the ultimate nature of reality. As such, the issue of the nature of human beings arises and, in particular, how the human mind is related to the human body. Are we exclusively physical things with a physical mind (or brain)? Are our minds something over and above our physical bodies? Can our conscious minds continue to exist after bodily death? There are two broad traditional and competing metaphysical views concerning the nature of the mind and conscious mental states: dualism and materialism. While there are many versions of each, the former generally holds that the conscious mind, or a conscious mental state, is non-physical in some sense. On the other hand, materialists typically hold that the mind is the brain or that conscious mental activity is identical to neural activity. More generally, one can define materialism as the view that everything is material. One might instead opt for the somewhat weaker claim that mental activity depends upon brain activity without being identical or reducible to it.

It is important to recognize that by “non-physical,” dualists do not merely mean “not visible to the naked eye.” Many physical things fit this description, such as the atoms that make up the air in a typical room. For something to be non-physical, it must literally be outside the realm of physics; that is, not in space at all and undetectable in principle by the instruments of physics (though some dualists, such as Descartes in the seventeenth century, may have had “material” in mind when he used the term “physical”). It is equally important to understand that the category “physical” is broader than the category “material.” Materialists are called such because there is the understandable tendency to view the brain, a material thing, as the most likely physical candidate to identify with the mind. However, something might be physical but not material such as an electromagnetic or energy field. One might therefore instead be a “physicalist” in some broader sense and still not a dualist. Some authors prefer to use the term “physicalist” anyway but it is still no easy task to interpret the basic thesis that “everything is physical” (Stoljar 2008). Still, to say that the mind is non-physical is to say something much stronger than that it is non-material. Dualists, then, tend to believe that conscious mental states are radically different from anything in the physical world at all.

1.2 Dualism

There are a number of reasons why some version of dualism has been held throughout the centuries. For one thing, especially from the introspective or first-person perspective, our conscious mental states just do not seem like physical things or processes. That is, when we reflect on our conscious perceptions, pains, and desires, they do not seem to be physical in any sense. It was especially difficult, say, at the time of Descartes, to conceive of how a chunk of matter of any complexity could be conscious, let alone perform mental activities such as reasoning. That is, at that time, it was hard to understand how mental activity in general, not just conscious activity, could be wholly material. Consciousness seems to be a unique aspect of the world not to be understood in any physical way. Although materialists will urge that this completely ignores the more scientific third-person perspective on the nature of consciousness and mind, this idea continues to have force for many today. Indeed, as we shall see, it is arguably the crucial underlying intuition behind historically significant “conceivability arguments” against materialism and for dualism. Such arguments typically reason from the premise that one can conceive of one’s conscious states existing without one’s body or, conversely, that one can conceive of one’s own physical duplicate without consciousness at all. The metaphysical conclusion ultimately drawn is that consciousness cannot be identical to anything physical, partly because there is no essential conceptual connection between the mental and the physical. Arguments such as these go back to Descartes and continue to be used today in various ways (Kripke 1972; Chalmers 1996), but it is highly controversial as to whether they succeed in showing that materialism is false. As we shall see later in this chapter, materialists have replied to such arguments and the relevant literature has grown dramatically in recent years.

Historically there has been a link between dualism and a belief in immortality, and hence a more theistic perspective than one tends to find among materialists. Indeed, belief in dualism is sometimes even explicitly theologically motivated. If the conscious mind is not physical, it seems more plausible to believe in the possibility of life after bodily death. On the other hand, if conscious mental activity is identical to, or even merely depends on, brain activity, then it would seem that when all brain activity ceases, so do all conscious experiences and thus no immortality. After all, what do many people believe continues after bodily death? Presumably, one’s own conscious thoughts, memories, experiences, beliefs, and so on. Nonetheless, we should try to evaluate the dualism–materialist debate on its own merits to the extent possible.

One might of course wonder, “even if the mind is physical, what about the soul?” Maybe it’s the soul, not the mind, which is non-physical as one might have learned in many religious traditions. While it is true that the term ‘soul’ (or ‘spirit’) is often used instead of ‘mind’ in such religious contexts, it is unclear just how the soul is supposed to differ from the mind. The terms are often even used interchangeably in many historical texts and by most philosophers because it is unclear what else the soul could be other than “the mental substance.” It is difficult to describe the soul in any way that doesn’t make it sound like what we mean by “the mind.” Again, that is what many believe goes on after bodily death, namely conscious mental activity. The term ‘soul’ carries a more theological connotation, but it doesn’t follow that the words ‘soul’ and ‘mind’ refer to entirely different things. Further, relying purely on religion to answer a scientific question has been disastrous in many past cases, such as the age of the Earth, that diseases were punishments from God, and that schizophrenia involved demon possession. Time after time, there has been long-standing resistance to scientific progress based on religious belief, with little to justify it especially when one looks back in retrospect.

1.2.1 Near-death and out-of-body experiences

Somewhat related to the issue of immortality, the existence of near-death experiences (NDEs) is also used as some evidence for dualism and immortality. Some patients, often in cardiac arrest at a hospital, experience a peaceful moving through a tunnel-like structure to a light and are often able to see doctors working on their bodies while hovering over them in an emergency room (sometimes akin to what is called an “out-of-body experience” or an OBE). These are often very moving emotional experiences which have a profound effect on those who experience them. In some cases, the patient sees other deceased relatives and exhibits little or no electroencephalograph (EEG) activity. In response, materialists will point out that such experiences can be artificially induced in various experimental situations, and that starving the brain of oxygen is known to cause hallucinations. This “dying brain hypothesis” is also bolstered by the notion that the release of endorphins during times of stress and fear can explain the feelings of peacefulness and pleasure. Interestingly, air force pilots can have at least somewhat similar experiences and often pass out when testing their ability to handle centrifugal force while training in a centrifuge which whips pilots around in a circle at high speeds. We must remember that NDEs are supposed to be “near death” not “after death,” and thus some brain activity is presumably still present during the time of the NDE (even if not always detected by the EEG which measures only very surface brain activity). Of course, if it could ever be shown that one is having a conscious experience at the time there is no brain activity, then this would indeed be strong evidence for dualism. I am not aware of this scenario actually occurring. Part of the problem of course is the methodological difficulty of performing controlled and repeatable experiments. Some mystical and religious experiences can often share some of the features of NDEs but some also result from temporal lobe epilepsy.¹

An OBE occurs when one seems to perceive the world (and often one’s own body) from above or outside one’s body. You feel like you have left your body and are “floating” above it. This seems to indicate a separate “mind” or “soul” separating out from the body. However, materialists explain how very similar experiences can be easily induced by stimulating neurons in the temporoparietal junction in the right side of the temporal lobe (Blanke et al. 2004; Blanke and Arzy 2005). In the late 1960s and 1970s, five-digit numbers were placed on a shelf above an emergency room bed with very poor results as patients having OBEs were unable to “see” the numbers. As odd as it sounds, it seems that the normal correlation between body image and visual input can become dissociated, which is sometimes also seen in patients with seizures. This would seem to take much of the force out of the OBE-related arguments in favor of dualism. Also, how exactly is dualism supposed to help to explain these phenomena? What is the “phantom body” made out of? How can it interact with the physical body? If it is really non-physical, then how can it have a physical location over one’s body?

Various paranormal and psychic phenomena, such as clairvoyance, faith healing, and mindreading, are sometimes also cited as evidence for dualism. However, materialists (and even many dualists) will first likely wish to be skeptical of the alleged phenomena themselves for numerous reasons. There are many modern-day charlatans who should make us seriously question whether there really are such phenomena or mental abilities in the first place. They unethically take advantage of the gullible and vulnerable, often with methods used by magicians. One might think that such astounding abilities could be captured on video and really lead to some incredible repeatable results and accurate predictions. Second, it is again not quite clear just how dualism follows from such phenomena, even if they are genuine. A materialist, or physicalist at least, might insist that though such phenomena, if genuine, are puzzling and perhaps currently difficult to explain in physical terms, they are nonetheless ultimately physical in nature; for example, having to do with very unusual transfers of energy in the physical world. The dualist advantage is perhaps not as obvious as one might think, and we need not jump to supernatural conclusions so quickly.

1.3 Substance dualism and objections

1.3.1 Interactionism

Interactionist dualism, or interactionism, is the most common form of “substance dualism.” Its name derives from the widely accepted fact that mental states and bodily states causally interact with each other. For example, my desire to drink something cold causes my body to move to the refrigerator and get something to drink and, conversely, kicking me in the shin will cause me to feel pain and get angry. Due to Descartes’ influence, it is also sometimes referred to as “Cartesian dualism.” Knowing nothing about just where such causal interaction could take place, Descartes speculated that it was through the pineal gland, a now almost humorous conjecture. The pineal gland is a small gland in the vertebrate brain located between the two hemispheres. But a modern-day interactionist would certainly wish to treat various areas of the brain as the location of such interactions.

Three serious objections are worth mentioning here: (1) One is simply the issue of just how do or could such radically different substances causally interact. How does anything non-physical causally interact with something physical, such as the brain? No such explanation is forthcoming or even seems in principle possible since one side of the causal relation is, by definition, non-physical. Gilbert Ryle (1949) mockingly calls the Cartesian view about the nature of mind a belief in the “ghost in the machine.” Moreover, if causation involves a transfer of energy from cause to effect, then how is that possible if the mind is really non-physical? Energy is still a physical constant embedded in every system of physics.

(2) Assuming that some such energy transfer makes any sense at all, it is also then often alleged that interactionism is inconsistent with the well-established scientific Conservation of Energy principle, which says that the total amount of energy in the universe, or any controlled part of it, remains constant. So any loss of energy in the cause must be passed along as a corresponding gain of energy in the effect, as in standard billiard ball examples. But if interactionism is true, then when mental events cause physical events, such as when my desire to drink something cold causes my body to move to the refrigerator, energy would literally come into the physical world. On the other hand, when bodily events cause mental events, energy would literally go out of the physical world. At the least, there is a very peculiar and unique notion of energy involved, unless one wished even more radically to deny the conservation principle itself.

(3) Perhaps most importantly, a materialist might use the well-known fact that brain damage (even to very specific areas of the brain) causes mental defects as a serious objection to interactionism (and thus indirectly as support for materialism). Surely the most straightforward explanation for this fact is that the brain area in question is identical to the normal mental activity in question. It has long been known that brain damage has negative effects on one’s mental state and alters (or even eliminates) one’s ability to have certain conscious experiences. Even centuries ago, a person would much prefer to suffer trauma to one’s leg, for example, than to one’s head. The implications of this have not been completely lost on most philosophers. For example, it thus stands to reason that when all of one’s brain activity ceases upon death, consciousness is no longer possible and so neither is an afterlife. It seems clear from all the empirical evidence that human consciousness is at least dependent upon the functioning of individual brains. Having a functioning brain is, at minimum, necessary for having conscious experience, and thus conscious experience must end when the brain ceases to function.

The level of detailed knowledge about the mental function of brain areas has of course increased dramatically in recent years. Very specific mental changes occur when, and only when, very specific brain damage occurs. It is true that such a “correlation” is not the same as an identity or cause, but the simplest explanation for the neuropsychological evidence is clearly that conscious mental activity is, or at least depends upon, the relevant brain activity. For example, in humans, damage to particular brain regions, such as due to disease, trauma, or stroke, is associated with specific impairments of perception, memory, cognition, emotion, and decision-making. Drugs that alter brain activity produce corresponding changes in perception, memory, cognition, emotion, or personality, depending upon the neurotransmitter systems involved and particular brain regions affected. Loss of vision results from damage to areas of the visual cortex (in the back of the brain). Loss of hearing or the ability to recognize sounds, including speech, results from damage to regions of auditory cortex within the temporal lobes. Prosopagnosia, the inability to recognize familiar faces, is typically caused by damage to the occipito-temporal cortex (the fusiform gyrus). Damage to brain regions involved in emotional regulation, which include the limbic system, particularly the amygdala, commonly results in impaired processing of emotional stimuli. Furthermore, numerous neurological disorders and diseases, such as Alzheimer’s, bipolar disorder, amnesia, depression, schizophrenia, epilepsy, and mental retardation, which are all characterized by profound changes in cognitive function and awareness, are all associated with specific biochemical, neurophysiological, or neuroanatomical changes in the brain (see Chapter 4 as well). While some of the specifics are still not fully understood, w...

Table of contents

• Cover Page
• Consciousness
• New Problems of Philosophy
• Title
• Copyright
• Contents
• Acknowledgements
• Introduction: The Problem of Consciousness
• 1 The Metaphysics of Consciousness
• 2 Consciousness, Neuroscience, and Attention
• 3 Representational and Cognitive Theories of Consciousness
• 4 Consciousness and Psychopathology
• 5 Animal and Machine Consciousness
• Concluding Thoughts and Future Directions
• Glossary
• Bibliography
• Index