The confusion which reigns supreme on the subject of consciousness is due to the fact that nobody has an objective valid definition of consciousness, or indeed any subjective human experience, and nobody can have one, as I hope to explain. As a result of this impossibility of defining consciousness, people talk about things that are not really consciousness or a subjective experience - just the physical phenomena, such as brain waves, brain responses to stimuli etc., which may be correlates of consciousness, but cannot be consciousness itself because correlation does not imply causation. That is an obvious and accepted principle of good science, that some scientists in the field of consciousness seem to regularly ignore.
To understand clearly the place of consciousness in science, we must distinguish between objective science and subjective science. Objective science involves itself exclusively with the rules governing the behavior of matter. Subjective science deals with the personal, individual experiences of each human being.
All objective phenomena must be detectable and measurable entirely by material means. This implies that experiments to detect any property of matter must be possible to perform using material means only and not having to rely on the truth of reporting a human experience. This means that consciousness and all of our subjective experiences cannot be material properties because if they were they would be detectable by physical means, and not just through their correlation with physical phenomena.
For example, in physics a magnetic field, though invisible, is absolutely correlated with the current in a wire. The magnetic field can be independently detected by its properties of inducing a current in a wire. The magnetic field is therefore detectable physically. Its definition is easily expressed in terms of its properties. It can be detected and is defined entirely by its physical properties. There is nothing beyond those physical properties in a magnetic field. Anything that has those detectable physical properties is by definition a magnetic field. Therefore physical instruments can detect a magnetic field through its properties and any person can repeat such detection to confirm its validity.
Nothing of that nature is possible concerning consciousness. Consciousness, being a human experience, is by definition a subjective. The only possible verification of any subjective experience is by the experiencer. You cannot verify my experience, because only I experience it and I cannot verify yours because only you experience it. Therefore we cannot provide an objective definition of consciousness.
Subjective experiences are by definition the experience of an individual and no individual can testify objectively to any experience of another. It is a reasonable belief that we all experience certain subjectivities in similar ways, but that is a belief, not an objective fact. Objectively I cannot even prove that any of you reading this are subjective beings, experiencing all that I experience, rather than zombies, acting in every way like a subjective being, but not experiencing anything.
And that is the core of the matter of consciousness. To say that the definition of the experience of the color red is the activation of certain parts of the brain, is incorrect. All that can be said is that whatever this “red” experience is, the respective parts of the brain are activated during that experience in those subjects we have tested. Again, any such observations of brain activity signify only the correlation of a reported experience (subjective) and the objective detection of brain activation, and not a detection of the experience itself, which can never be detected, because it is only experienced by the individual.
That is also the reason we can never come up with the definition of consciousness. To say that our consciousness is an illusion, as some physicalists would have it, is an unreasonable, self-inconsistent and circular proposition which can never be objectively proved. It demands a definition of “illusion” which is also a subjective and so has no possibility of an objective definition. In addition, an illusion refers to a person’s conscious experience and therefore relies on consciousness, the very word that is being defined! No material object can experience an illusion, only conscious beings can experience an illusion and whether consciousness is an illusion or real can never be tested objectively because there is no objective way of testing for consciousness. Here I assume that illusions are subjective experiences of physical events that can be objectively tested for their veracity. So for example if one moment I see an object in the hands of a magician and the next moment I do not see it, leading me to conclude that it has disappeared, I see an illusion whose lack of veracity can be physically tested.
If anyone believes such illusion statements about consciousness, they should consider how they would respond to the doctor telling them that the pain they feel in their back is an illusion! I know what I experience, but I cannot define it and neither can you, whose experience may be quite different from mine.
The only explanation of the mind-body problem, which can explain all the numerous experiences in the field which are now being reported, is that the mind is the seat of our consciousness, it is the real us, and is quite different from the body and a separate non-material entity, an entity which can only experience the physical world using the physical brain and body as its instrument.