I will begin by clarifying the first two theories along with showing their limitations. Then I will move on to the brain-body-environment explanation and how this theory improves on the two others.
The argument which reduces mental states (consciousness) to neuronal firings is called type identity theory. The main notion is that mental events are nothing over and above brain events; so essentially the mental is the brain and vice versa; there are no physical/brain facts outside of mental facts. This notion has the closest connection to the physical sciences, yet it is not without its shortcomings and pitfalls. There are four major problems with this theory; they are: Category Error, Lack of one-to-one match ups/The Binding Problem, Blind Positivism, and Multiple Realization.
Category error’s meaning is explicit; the error here is trying to get a third-person phenomena to explain a first-person experience. Most would agree that there is a huge difference between test anxiety and the fluctuating sodium-potassium currents within neurons. Therefore this problem affirms that mental states are in a different category then physical events; thus the first person perceptive or consciousness cannot be reduced to third person or neuronal firing. My experience of red is not the same as chemicals crossing a gap in-between neurons.
Identity theory has not given us a neat one-to-one match up between brain activity and consciousness. At best it has pointed toward the neo-cortex as the “seat of consciousness” yet that has shown to be very hard to prove. This elusive search for the neural correlates of consciousness has brought up an issue named The Binding Problem: this explains the lack of a brain region reasonable for condensing all of your sensory data and memories into a complete and unified experience (the preset moment). To illustrate, the region of your brain which calculates color is not anywhere near the area responsible for determining shape. So what neuroscientists are puzzled over is the lack of a spot which takes the various independent mechanisms of mind/senses and concentrates them into the one unified experience we have.
Blind positivism refers to the blind faith that science will understand and explain all things. Here specifically the faith is that science will eventually explain consciousness. The setback wrought is the belief that empiricism can explain non-empirical phenomenon. Consequently this requires a leap of devotion to believe that science can investigate what it can’t measure. Although the future does holds surprises, it’s still too early to grant or wish science more power than what it presently has.
Finally Multiple Realization upholds that any given mental state such as pain or hunger is realizable in a wide array of physical or biological structures like other animals or aliens. So pain is not dependent on physical mechanism if the same mental state can be realized by different mind-organizations or brains. In other words, mind states are not dependent on brains.
Moving on to functionalism- a step in the right direction because of its recognition of relational systems. This theory insists that consciousness (mind) is not just the brain per se, but rather a network of functional mental states. To illustrate, a car can take on various shapes and sizes. Yet no matter what form the car takes, its function remains the same. The same idea is applied to consciousness, it can be realized through different kinds of brains and bodies, but ultimately it results in the same kind/type of mental state or consciousness. Thus functionalism defines consciousness not merely as a collection of neurons but instead as a system of interrelations between mind states.
There arise two key problems with the functionalist view: neural autonomy, and sentient computers.
Neural autonomy refers to the issue of whether human brains are the only systems capable of mental states or consciousness. (Most people’s intuitions would have them believe that our 3 pound hunk of meat is the only thing capable of “high” intelligence.) So as functionalism focuses on the system and not so much the brain itself, it leaves room for non-brain based systems of organization to acquire consciousness; some regard this as a problem for the theory while others maintain that problem is chauvinistic.
As for sentient computers, the thought experiment- The Chinese Room- demonstrates the augment between those who hold that computers can give rise to mental states like ours and those who believe it’s an ill-fated pipe dream. Briefly, the thought experiment explains a machine which is fed questions on note cards in Chinese and produces out answers on another note card. The people outside are ignorant as to what happens on the inside; within there is a system consisting of a book of algorithms and a man to compute them. So as one inserts a question from the outside, it appears interiorly and the man looks toward the algorithmic book to see how he would manipulate the symbols to produce the correct answer. Therefore the man has no knowledge of Chinese (semantics), but only how to read and interpret the symbols according to the algorithms in the book (syntax). This thought experiment is designed to show how no computer no matter how sophisticated can come to realize a mental state like ours defined be intentionality and meaning. However some argue that the same can be said about individual neurons- they are all simple/dumb and incapable of knowing our conscious experiences like the man in the room, yet they are thought to produce consciousness on their own. In order to discuss this radical explanation for consciousness- the interaction mind-body-world model- we must return to one major assumption postulated by type identity theory: changes in brain states cause changes in mind states- because they are non-synonymous expressions that refer to the same phenomenon, therefore brains are minds. This is irrefutable yet fails to tell the whole story of consciousness. Although it is true that brain changes cause mind changes, it is also equally true that changes in environment and/or body also can cause changes to the mental. For example, a lobotomy can change behavior as much as a dramatic life event such as major loss of family, damage to the body or slaughtering of one’s community can; even traveling to extremely unfamiliar cultures can cause delirium like some surgery can. For that reason, saying the brain is only responsible for consciousness is like saying the stomach is only responsible for digestion or that the heart is only responsible for bodily blood flow. All in all, brains are necessary but not sufficient for consciousness.
Common sense would have us believe that we are located some where behind the eyes and in-between the ears- probably because four of our five sense organs are on the head. Nevertheless common sense also tells us the world is flat and that the sun orbits the earth. Yet intuition is hard to shake off. While I feel like an island to my self- that being subjectivity- I am anything but. My life is composed not of isolated affairs but interconnected dealings. We do not exist in vacuums all to ourselves; our identities are known by virtue of our relations with the world. We come to know ourselves by our associations with the world. We cannot know ourselves without knowing others; our mental states are defined by the access we have to the world.
In the same way neuroscientists are searching for the neuro correlates of consciousness, there are also external correlates of consciousness- the latter are our habits. As one can tell, the content of consciousness owes more to external interactions then with isolated self-representations of those interactions. Seeing the world through the prism of our personality or self-schema does not refute the fact that we have direct access to the world and are apart of it.
The brain is apart of a loop or network where it plays an important but not adequate roll. Scientists claim that consciousness is not generated by any single neuron but it is realized as the system of interconnected neurons. Why stop there? We can take the next step and see how the brain is apart of a larger network- the body and environment- which when interconnected gives rise to consciousness. Taking that step can be tough because old assumptions/intuitions die hard. Therefore consciousness does not happen inside the brain, but rather it is attained, achieved or accomplished when the brain, body, and world all intersect. Thus machinery of the mind is not confined to what is within the skull because the complex system of consciousness is apart of an continuous chain of interaction of brain-body-world.
In biology when one studies an animal, they are also describing to some extent its surroundings. So one cannot explain either animal or environment in isolation, they are always in relation. All life or mind is always a situation between organism and world. The environment is not separate from us, we come from it- we are it. To quote the philosopher Alan Watts: “The earth peoples in the same way an apple tree apples… therefore we come from the earth like an apple from a tree.”
This model improves on type identity theory by pointing out its prime assumption as limited. Furthermore, this interaction theory improves on functionalism by focusing the topic back to physics and away from abstracted non-empirical “mental states”.
Consequently, as radical this idea is, it fits perfectly with materialism/physicalism- consciousness is a result of the interactions of physics- there is no room for dualism or the “ghost in the machine“. It may be tough to understand our minds as being more than just our brains, but when we carefully analyze the content of our consciousness, we see that our access to the world is like an uninterrupted loop/network where our brains are just one node/interface of interactions amongst others. Consciousness is generated not only by the brain, but the amalgamation/collaboration of brain-body-world. Although the environment is not an extension of the feeling part of our nervous system like the skin is, it is still apart of us that if it where to be changed, our mental states would be altered as well.