Consciousness refers to the experience of being.

Each being's consciousness is distinct to a degree we can not know without making some metaphysical and other assumptions.

We assume that particular beings, like you, have a consciousness that is aware of any number of events in and upon you at any given time. Because consciousness is not publicly available, we all must assume the consciousness of others. By others, I mean not only other humans but also any other entity that displays the behavioral characteristics of a conscious being.

Beings with nervous systems, we assume, can feel pain because we can observe their reactions. But, our ability to create assumptions about the consciousness of entities fails as we stray further from our own composition. The question of whether there is anything it is like to be a tree is forever open because such beings cannot report or react in a way that we can translate into our own experience.

We assume that a tree can not feel pain because it does not have the apparatus that creates pain in humans and animals. But, that does not mean the tree does not experience at all or even that the tree does not experience pain. What the tree's experience is or is not like can simply not be assumed or expressed at all.

It is at least conceptually possible that you are the only conscious being in existence and everyone and everything else is not. This is called solipsism. But, there is certainly no reason to assume this possibility. There is, however, good reason, in the form of not wanting to cause pain, to assume that everyone and everything that behaves as if it ihas consciousness does, in fact, posess consciousness.

From 2000:

A Skeptical Solution to the Problem of Consciousness

“Consciousness is what makes the mind-body problem really intractable.” (Opening line of Thomas Nagel’s What Is It Like to Be a Bat?)

The problem of consciousness, which is a fundamental difficulty in the mind-body problem, has been diagnosed in a variety of ways in recent philosophical, psychological, and neuroscientific literature. However, if one surveys this literature, there is little agreement upon what the term consciousness actually refers to. In scientific models of consciousness, what I take to be an ordinary understanding of the term consciousness is consistently missing.

The common understanding of the so-called ‘hard’ problem of consciousness is what Block defines as phenomenal consciousness, as opposed to the more mundane access consciousness. Phenomenal consciousness, I believe, is the type of consciousness we mean to refer to when we speak of consciousness. Phenomenal consciousness includes awareness, presentness, and other characteristics that are absent from accounts of access consciousness.

My thesis is that we have no epistemic justification for believing that consciousness is anything other than a conceptual model through which we externally and internally communicate intentional states. In furthering this skeptical hypothesis, I will demonstrate that the type of consciousness argued for in various thought experiments (Block, Searle) is not actually existent in the physical world and is not even possibly existent in any physical world.

In support of this view, I will demonstrate that (1) a priori analyses of our concepts reveals nothing about the metaphysical nature of consciousness, (2) if consciousness does not exist, then there still may be systems that firmly believe that they are conscious, (3) the notion of consciousness, like the notion of self, has no special referent, and (4) we have no reason to suppose that physical systems which satisfy certain basic criteria would not internally and externally seem to posses (a) minds, (b) selves, and (c) consciousness.

If my thesis that consciousness is not a possible property of any physical system is true, then the persistant gap in philosophy of mind between the brain and consciousness will turn out not to be an actual gap, but a gap stemming from a misconception about the metaphysical nature of our concept of mind.

Introduction: What is Consciousness?

One of the most pressing problems in all of the various discussions surrounding consciousness is that there is no agreement upon exactly what consciousness actually is. A number of attempts have been made at clarifying what we mean when we speak of consciousness. Ned Block has argued that we should distinguish access consciousness from phenomenal consciousness.

However, as a number of philosophers have pointed out , access consciousness does not seem to be the type of consciousness being referred to when we ordinarily speak of consciousness precisely because there is no phenomenal awareness involved in access consciousness.

A prime example of this is the much-discussed case of blindsight, in which someone can react to her environment based purely on instinctual guessing rather than awareness. In a classic example of this, a blindsighted subject is presented with a cup and asked if she sees a cup in her visual field.

The subject responds negatively. However, if the subject is asked to point to the cup if she had to guess at the location of such an object, the blindsighted subject can, in most cases, point to the location of the cup that she has no phenomenal consciousness of.

This empirical finding demonstrates that there are processes in the brain that can recognize objects, categorize them according to conceptual kinds, and relate the spatial location of these objects to motor functions that point out such objects without the phenomenal awareness of the subject.

It may be pointed out that the subject must first be prompted, but this is a necessity of the experiment. It is likewise a possibility that upon wanting a cup of coffee, the subject may reach out for the cup without realizing that the cup is actually there, only to find through tactile sensation, that there is a cup in front of her.

From 1999: Pain and Black Holes:

An example of a concept of consciousness comes about when we think of pain. If I were to lay a man on a machine that could somehow trace and collect all of the physical data from his body, then I could see, at every moment, what the physical mechanisms in his body are doing. If I prod this man with a sharp stick in his arm, then this physical stick will cause him to have pain, but we would not deny that the pain can be seen physically. At the moment I poke this man in his arm, his nervous system has an electro-chemical response through his arm, to his spine, up to his brain, and back again. Once this signal is in the brain, it acts in such a way to make this man react. And, we can see that these physical things must happen for him to have a "mental" impression of pain. In this way, the physical happenings trigger "mental" happenings. The problem lies in how he sees this pain, he is experiencing pain, but not in the way that I can see with all of my medical instruments. He is subjectively feeling this pain, he is experiencing a "painfulness" that can not be tested by an external observer. Therefore, this "painfulness" is something unexplainable, something we can not touch, something we will never see. This is true.

"Unstill Life of Wine Glass, Grapes, and Decanter", 2005, by Anthony Peter Iannini

But, the same is true of a black hole in space. We will never be able to test a black hole. We can never get inside of it, we can never see what is really in there.

But, does this mean we should assume that the black hole is somehow a substance beyond that of the physical substance from which it was made? What reason do we have to assume that something new is created in this ultimately dense body of physical matter?

The Hand Meditation: Lift up your hand and hold it in front of you, so that you can clearly see it. Stretch out your fingers and then make a fist. What are you doing here? You are thinking. You are moving matter by using your mental abilities, you are thinking and moving something directly connected to that thought.

Directly connected must mean some ability to stimulate that matter in question in such a way as to move it, or to cause some change in it. Take a pencil, for example. You can think about it forever and it will not move. Your hand is merely matter, but it is somehow linked to your mental processes. Severe your arm, and what is left?

Is it still the same arm at the moment it is amputated from the rest of the body? Is there anything about the arm that we see as not having the same properties as it did when it was still attached to the body? If the connection between the arm and the mind is physically severed, and we can no longer control it mentally, then it is also mentally severed.

And if thought were something other than physical, how would we be able to break the mental connection as well as the physical connection at the same time?

This would mean that a knife can cut (like the arm) through mental substance, or that mental substance is so attached to the physical substance, that it is directly proportional to the physical substance in question. So, if the mind exists in the brain (somewhere) and we cut out a piece of someone's brain, then we have too, cut out a piece of their mind.

If this is not the case, then you would still be able to move the detached arm unless there is something I am not seeing in this argument. Why is it that we see a mental substance when it is so completely joined with the physical substance that the two are completely inseparable?

The Hand Meditation in Sequence:

[a] Move your hand in front of you.

[b] You are somehow controlling the movement of your hand through thought.

[c] You can not do the same with objects that are not part of your body (a pencil).

Lets say that anything you are in physical contact with becomes a "part" of your body.

[d] Cut off your arm and it becomes an object not part of your body.

• The physical connection has been severed.

• The mental connection has been severed.

• The mental and physical connections are either (1) or (2) or (3).

(1) So dependent on one another that they are inseparable.

(2) There is no physical connection, but only a mental one.

(3) There is no mind connection, but only a physical one.

One (1) is like the modern distinction between matter and energy. One can not exist without the other, and when things are so closely related as to be inseparable, we may as well call everything 'matter' or call everything 'energy', but not waste time calling it both matter and energy when its nature is really in one thing.

If case (1) were true then either case (2) or case (3) could be seen as true because if either mind or body is so connected with one another that they are inseparable in terms of disjoining a part (arm from the body) then they can be considered one and the same. (like the modern distinction between matter and energy)

If case (2) were true, then there would be no physical body. If we want to assume that we are without bodies then we can allow this. The reasons that we have to assume we are in bodies, or that we are, in some way, physical entities, are striking. The difference between a dream and being awake are stark, the difference between a hallucination and the consistency of the reality in which we all agree are stark.

Then, it seems, the only remaining case is (3), in which there is no mental connection, but only a physical one.

If we use the same situation for a part of the human brain, we may say that removing a part of the physical brain, say the frontal lobe, is removing merely a physical part of the brain. Because in case (1) we are now also removing the mental aspects of that part of the brain, and therefore may consider this one thing rather than separate physical and mental 'stuff'.

We are again left with the choice of either (2) or (3). If we choose (2) then we are boldly assuming that there really is no matter to our brains, a path of thought that I am not willing go down for reasons previously stated.

But, if we will assert that there is a physical nature to the human body, we must, it seems, choose that there must be only a physical connection on the grounds that (1) means nothing more than mind and body are so related as to be inseparable that  it is like the modern distinction between matter and energy which has been shown to be nothing more than a distinction between two modes of the same 'stuff'.

Consciousness and Immaterial Substance: How is it that we can create a kind of non-physical substance, a soul, a mind, based on our ability to reflect and think that we are thinking?

It seems that the term "consciousness" has been looked at in the wrong light, that the language used to relate the idea of inner awareness has skewed our thought about it. I believe that the problem of consciousness lies in the word and concept itself, not in reality.