Phenomenal Consciousness

Understanding the Relation Between Experience and Neural Processes in the Brain

Dimitris Platchias

• Publisher: Routledge
• Year: 2014
• Print ISBN:
  9781844652495
• eBook ISBN:
  9781317491866
• Topic: Philosophy
• Subtopic: Philosophy History & Theory

How can the fine-grained phenomenology of conscious experience arise from neural processes in the brain? How does a set of action potentials (nerve impulses) become like the feeling of pain in one's experience? Contemporary neuroscience is teaching us that our mental states correlate with neural processes in the brain. However, although we know that experience arises from a physical basis, we don't have a good explanation of why and how it so arises. The problem of how physical processes give rise to experience is called the 'hard problem' of consciousness and it is the contemporary manifestation of the mind-body problem. This book explains the key concepts that surround the issue as well as the nature of the hard problem and the several approaches to it. It gives a comprehensive treatment of the phenomenon incorporating its main metaphysical and epistemic aspects, as well as recent empirical findings, such as the phenomenon of blindsight, change blindness, visual-form agnosia and optic ataraxia, mirror recognition in other primates, split-brain cases and synaesthesia.

1. THE NATURE OF THE MIND

1.1 SUBSTANCE DUALISM

In this chapter, I shall present the main philosophical positions on the nature of mentality, such as substance dualism, physicalism and functionalism. This will enable us to locate the subject matter of this book within broader discussions of the mind-body problem. In this section, I shall look at substance dualism and, in particular, at the Cartesian conception of the mind. René Descartes’ project in the Meditations on First Philosophy is a quest for indubitable truths. Descartes famously applies the method of universal doubt to “all things” in an attempt to empty the mind completely of all traditional views and preconceived ideas in order to show beyond all further doubt that truth is possible. To do this, he lays down three increasingly powerful layers of doubt. He begins his enquiry by doubting the “deliverances” or the “testimony” of the senses. Surely there is a clear sense in which our senses can deceive us; cases of perceptual error, such as illusions and hallucination, are suggestive enough. His next step was to claim that he sees “so manifestly that there are no certain indications by which we may clearly distinguish wakefulness from sleep that I am lost in astonishment. And my astonishment is such that it is almost capable of persuading me that I now dream” (1996: 13). According to Descartes, since his vivid dreams were indistinguishable from waking experience, it was possible that everything he “saw” to be part of the external (physical) world outside him was, in fact, nothing more than a fabrication of his own imagination. It was then possible to doubt that any physical thing really existed or whether there was an external world at all. Descartes’ final step was to introduce the “demon” hypothesis: the possibility that there is “a malignant demon who is at once exceedingly potent and deceitful” (1998: 12) that not even these items of knowledge can survive.

These three grounds of doubt share the same structure: the senses may or may not deceive you, you may or may not be dreaming, and there may or may not be a demon around trying to deceive you at all times. The underlying idea is that we think we are in the good circumstance where our experiences are veridical and accurate, or where we are not dreaming and an external world exists, or where there is no deceitful demon. However, we might be in the bad circumstance where the opposite is true and where an evil demon is deceiving us. Our evidence would be just the same in the bad circumstance as in the good circumstance. Therefore we cannot know that we are in the good circumstance rather than in the bad: since our evidence in the good circumstance is the same as in the bad circumstance (there are no distinguishing marks between them) then even if we are in the good circumstance, we do not know that we are.

Descartes eventually lands on a bedrock certainty capable of withstanding even his worries about a deceptive demon: “But I have convinced myself that there is absolutely nothing in the world, no sky, no earth, no minds, no bodies. Does it follow from that I too do not exist? No: if I convinced myself of something then I certainly existed” (1996: 16–17). If I can be deceived, then I must exist. Cogito ergo sum. From establishing that I am, Descartes wants to know what I am. Following his general line of argument, it seems that one cannot say more than “I am a thing that thinks”, res cogitans. Thinking that one has a body, or big arms, or that, say, he was born in Greece, are all immediately vulnerable to doubt. All that Descartes seems to know as to his nature is that he is a thinking thing, not that, say, he has a body. He can doubt that he has a body, but he cannot doubt that he has a mind.¹

This can be summarized in what some philosophers call the Cartesian epistemological argument for the idea that minds and bodies are distinct, as follows:

P1.	I cannot doubt that my mind exists.
P2.	I can doubt that my body exists.
Conclusion.	My mind is not identical with my body.

How good is this argument? Arguments are generally tested for validity and soundness. An argument is valid if it is impossible for its premises to be true and its conclusion false. Here is an example:

P1.	Andrea Bocelli is an opera singer.
P2.	All opera singers are musicians.
Conclusion.	Andrea Bocelli is a musician.

When we ask whether an argument is valid or invalid we look at the argument as a whole to see whether its premises are related in this particular way: it would be impossible for the premises to be true but the conclusion false. If an argument is invalid then even if the premises were true, it would still be possible for the conclusion to be false. In other words, if the argument is invalid then the conclusion does not follow from the premises. An argument is sound if and only if it is valid and all its premises are (actually) true. So if the argument is valid, this means that if the premises are true then the conclusion cannot be false. Hence, if the argument is valid, it is worthwhile examining whether the premises are in fact true. Since a sound argument is a valid argument with true premises, it follows that there cannot be a sound argument with a false conclusion. There are, then, two steps in assessing an argument (in that order): test the argument for validity and test the argument for soundness.

So, is the above stated argument valid? This argument has the following structure:

P1.	I cannot doubt that a is F.
P2.	I can doubt that b is F
Conclusion.	a ≠ b

If we can find an argument with this form, then, that has true premises and a false conclusion, we will know that this argument is not valid.

P1.	I cannot doubt that Spiderman is Spiderman.
P2.	I can doubt that Peter Parker is Spiderman.
Conclusion.	Spiderman ≠ Peter Parker.

You can imagine a situation where both P1 and P2 are true (e.g. Gwen Stacy, Peter’s first girlfriend, was in this situation) but obviously the conclusion is false. So even if both premises of the epistemological argument were true, that would not be sufficient for establishing the truth of the conclusion. Here is another example where both premises are true but the conclusion is false:

P1.	I cannot doubt that 12 is 12.
P2.	I can doubt that ^3✓l728 is 12.
Conclusion.	12 ≠ ^3✓l728.

So the epistemological argument is not valid and we should not believe that the mind is not the body because of it.²

Descartes however, observes a number of differences between minds and bodies. According to him, there are certain attributes that can be ascribed to minds only and not to bodies, and vice versa. If that is right, then it does make sense to say that the mind is not the same thing as the body. This is because of Leibniz’s law of the indiscernibility of identicals, crudely put as follows: X is the same thing as Y if and only if (iff) whatever is true of X is also true of Y or, in other words, iff whatever holds for X holds also for Y.³

Recall the Spiderman example. Although it does not make much sense to ask if Peter Parker is Peter Parker (or if Spiderman is Spiderman, for that matter), it makes perfect sense to ask if Peter Parker is the same person as Spiderman. Are they the same person? If they are, then it must be the case that whatever is true of Peter Parker it is also true of Spiderman. It cannot be for instance, that Peter Parker occupies a certain location in space at a certain time and Spiderman is not there, or that Spiderman is to the left or to the right of Peter Parker (as it happens with things that are qualitatively, but not numerically identical, such as identical twins or MP3 players).

The apparent differences between minds and the bodies – that certain things are true of only the former and certain other things are true of only the latter – led Descartes to the conclusion that minds and bodies are, in fact, distinct. But he did not stop there. Descartes observed that the differences between minds and bodies were so eminent and of such a fundamental nature that he exclaimed that minds and bodies are not only distinct or different things, but that they are different kinds of things; they are different substances, made of fundamentally different stuff, mental and material (or physical) stuff, respectively. In his view, a human person is a composite entity consisting of a mind and a body, each of which is an entity in its own right.

According to Descartes, then, in a position invariably called substance dualism, there are two sorts of substance: mental and material (or physical). These are substances of two fundamentally and irreducibly distinct kinds in this world; namely, minds and bodies. A “substance”, according to Descartes, is a thing that exists in such a way as to stand in need of nothing beyond itself in order to exist. The main characteristic of a substance is the capacity for independent existence. So if you think that minds and bodies are different substances then they need nothing beyond themselves in order to exist, that is, they do not depend on each other in order to exist: the mind can exist without the body existing and vice versa.⁴

A helpful way to imagine a “substance” is to think of it as some sort of an object that persists through time. Objects (or things) are subjects of predication, that is, we normally attribute predicates or properties to them, such as “green”, “tall”, “low-fat”, “fast” or “to the left of”. Objects do not have to be concrete; we attribute properties to human and non-human primates and to chairs and tables but we also attribute properties to things such as clouds, flames and the sea. But we cannot attribute them, both concrete and non-concrete objects, to anything else. Further, the properties attributed to those objects cannot exist without these objects existing: “redness” cannot exist without the rose existing and “small” and “cuteness” cannot exist without the piggybank existing. A substance, then, can be thought of as an object that persists through time and changes, and has properties the existence of which requires the existence of the object.⁵

In what respects, then, do minds and bodies differ according to Descartes? As I said in the Introduction, it seems plausible to say that bodies can be accessed by means of the five senses and our knowledge of them involves precisely the exercise of our five modalities (and, possibly, proprio-ception). Contrariwise, knowledge of minds seems to necessarily involve the exercise of introspection, that is, the capacity to reflect on our mental lives, not perception. Thus, no matter how accurate your brain scanning is, no matter whether you are using positron emission tomography (PET) or functional magnetic resonance imaging (fMRI) scanning, or even if you use a very advanced technique and painlessly cut someone’s brain open, you will not be able to spot any of their perceptual experiences, beliefs or desires. Further, it seems that bodies, and material objects in general, have a location in space as well as properties, such as shape, size, weight and spatial orientation, whereas minds do not; you do not find yourself saying things such as “there’s a mind over there”, or “my beliefs are behind or to the left of this chair”, or “my memories of 2009 are 9 feet long and weight 14 stones”. Mental states just do not seem to be the sorts of things that are here or there or anywhere in the relevant sense and do not have any of the above characteristics that we normally attribute to material objects, or so it seems. Finally, it seems that minds can think and understand and imagine whereas bodies do not: intuitively, you do not believe that your body or your brain cells can, strictly speaking, understand, nor do you think that when John Lennon asks you to “imagine all the people living life in peace” he invites your left arm or medial temporal lobe of your brain to do this (Table 1.1).

There are other variants of substance dualism, apart from Descartes, such as Leibniz’s parallelism, Malebranche’s occasionalism and Huxley’s epiphe-nomenalism. The main difference between these views and Cartesian dualism is that Descartes held that the mind and the body could causally interact: minds and bodies causally influence each other; some mental phenomena are causes of physical phenomena and vice versa. This view is called interactionist dualism. Indeed, if you hold a substance dualist position, interactionism would seem the obvious position for there seem to be obvious truths of the following kind:

Table 1.1 Summary of the differences between mental and material substance according to Descartes

Physical substance: res extensa	Mental substance: res cogitans
Extended in space	Not extended in space
Has a spatial location	Has no spatial location
Not a thinking thing	Of essence a thinking thing
Known by perception	Known by introspection

Physical → causes → mental

Light hitting your eyes will cause you to have a visual experience.

Mental → causes → physical

Your decision can cause your arm to move.

If you are not careful enough and touch the red-hot oven with bare hand...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Acknowledgements
• Excerpts
• Introduction
• 1. The nature of the mind
• 2. Phenomenal consciousness: the hard problem
• 3. Phenomenal consciousness and the "sufficiency" claim
• 4. Experience and first-order representationalism
• 5. Experience and the explanatory gap
• 6. Experience and higher-order representationalism
• Notes
• Bibliography
• Index