There are two grand avenues when we speculate about the soul: either it is independent from the body or it isn't. I think that we will find out about the soul through scientific research, as the eons pass it will become an increasingly important and practical question, for the only way to achieve physical immortality, to download ourselves to artificial brains for instance, is to understand what the soul demands. But first we will need to see the functioning brain at a much better scale. Just as our understanding of the stars was changed through the invention of the telescope, so will the understanding of our brain, mind and consciousness will be made possible by the invention of new methods of observation of the brain.
Unlike Raymond Kurzweil, I do not find likely that such instruments will be discovered in my lifetime, so, my only chance of contemplating the truth is by imagining all the different hypothesis. I may never know which is the correct one but at least I will have a high probability of having contemplate the truth in the name of an hypothesis.
So let's start with the most comfortable hypothesis: there is an independent soul.
If there is an independent soul it cannot have the attributes that we normally attribute to the self. Why? Because people get sick, they have accidents, they become old, they may take drugs, and all of this changes and sometimes destroy our memories, our values, our cognitive abilities. So we know that those things are indeed dependent on the brain. For instance we cannot say that the soul "sees" objects or colors because we can close our eyes and then we won't be able to see a thing. Seeing colors, remembering, thinking, etc, are all done through a physical medium, the brain and its ramifications and, perhaps, with help from other parts of the body. If anyone doubts it we can simply take a part of his/her brain to prove it, although merely falling asleep will provide ample demonstration that what we are able to do, think and feel as human beings is indeed dependent on the brain.
Does that mean that there is no independent soul? Well, believing that I, Pedro, exist independently of my body, even though slight changes in my hormones, operations to my brain, diseases, experiences, education and old age might change me from top to bottom is an idea which I have difficulty to make sense of. Which part of me would be independent? I mean the Pedro that is writing now is very different from the Pedro that worked in a bank, or the Pedro that is strolling in is kayak, or the Pedro that writes poetry, or the angry or naughty Pedro, etc. Besides I was very different when I was a teenager, or when I was a child. Which part of me remains? I can certainly find a story of me, but that story may lead to so many different Pedros that I am at loss to understand an independent soul in any part of that mess. As far as I can see "Pedro", me, is a social and biological construct. It was born, it will function for a while playing all these different roles and it will die. That is "me": a social-biological construct.
So, in short, I cannot make sense of the hypothesis that I, Pedro, the self, am independent from the background from which I sprung forth. Even as a speculation it does not seem to make sense.
On the other hand there is something which seem to be in great accord with my experience: the soul not as the person but as a necessary condition for first person experience, we might call it, metaphorically, the eye inside the I. In other words, perhaps conscious experience demands the encounter of a physical system (full of information and the ability to interact with the world) and a "soul". Let me explain in detail what I mean by this: in my daily life I find that I can do many tasks automatically. I can read, write, stand up, ride my bike and my car in almost fully automatic mode. I can ride my car while day-dreaming, absolutely unaware that, like an orchestra, my hands and feet are moving to change the gears, brake, etc. When I'm standing on my feet I am rarely aware that the muscles on my feet and legs are always adjusting the balance so as to keep me from falling. Everything has been "programmed", and, once it is programmed, it works ok, without my intervention or conscious help or effort.
What cannot be done without consciousness is this initial effort of programming the right movements. How would a body learn how to walk automatically? There would be nothing saying: "that is right", or "that is wrong". So consciousness, as far as our experience goes, seems important when we learn something new, it is like a programmer that knows when the program is wrong and when it finally arrives at "the right results". But how does consciousness knows what is the "right answer"? Of course we don't know that (we don't even know if any of this is true), but we can imagine several hypothesis.
Well, here things get weirder. First of all, not all animals need to "learn" how to walk. In fact we are born knowing how to pee, how to cry, how to breathe, etc. In many other animals the diversity of innate abilities may be much bigger. The brain comes out already programmed, there is no need for what we call consciousness to enter the picture. So why don't we get born with all the stuff already imprinted, with the perfect program ready to be used? Well, many animals do. But the world is so diverse that a single program to deal with all the possibilities would demand a much more complex and complete line of commands than we can seen in any automated movement in the natural world. So our species, along with others, have chosen another strategy: instead of detailed commands for every possible situation, we have consciousness, which is a kind of general processing unit, that is able to focus on almost any kind of thing and then attempts to tell us which is the better choice.
But finding the right choice depends a lot on what our brain or program tells us about the problem is. If our inner ear is malfunctioning we might never be able to stand (Ménière's disease). If we perceive something as an enemy we will try to defend ourselves, put some distance or even destroy it. But a friend would elicit the inverse response: search for nearness, protect him, express our thoughts. What if we perceive a friend as a foe or vice-versa? The results can be catastrophic.
So we have two big limitations for consciousness if it exists as something independent of the body: First, it can program the brain only in a relatively long period of time. Consciousness has no direct control over the body but only on pre-learned, pre-programmed behaviors. It has to work the body through small steps, and then, even when the body was programmed over a period of many years, it cannot express itself fully but only the general direction in which the body must go. Secondly, when consciousness programs the body it has to do so, at least in large part, or even entirely, based on the description of the problem given by the body. But the body may give incorrect descriptions, for instance in early life regarding the interpretation of the senses. So the task of providing the body with functioning programs is complicated by the fact that it is based on a problematic vision of the world and on the fact that the program itself cannot be made in full detail, but only in a sort of general direction.
So, giving a practical example: suppose you are searching for a word you can't remember. You know that there is a word that more or less express what you are trying to say, but it does not come to mind. Now, the task of bringing it to mind is entirely of the brain, the search, and all the failed attempts are also the task of the brain. Consciousness, functionally speaking, has only a very simple role: it has to decide «it is the right word», or, «it is the wrong word». Perhaps it can also stimulate the brain in the right direction by trying to remember similar words or inducing a certain state of mind. But it is not entirely obvious that it can say more than a simple "yes" or "no".
On the other hand we would suppose that this "independent" consciousness is also necessary for experience, for a characteristic of automatic responses is that they are generally not associated with conscious experiences. Consciousness and the ability to decide if it is a "yes" or "no" seem to be interconnected, although it is not easy to see that connection.
(In all of this we are not demonstrating the independent existence of the soul, we are just attempting to provide a speculation that is somewhat coherent with our personal experience of what experience is and in which situations it is present and what role it plays in our lives. Now, in general, this soul or consciousness, is a sort of a guide. It provides general directions based on perceptions of beauty or ugliness, right or wrong, valuable or despicable, etc.)
We have seen that consciousness, this soul that we are tying to describe, has little power over the brain and body. It can point out general directions (like what to write) but its influence necessitates a healthy brain that is somewhat already programmed and open to further and appropriate influences. Moreover the task of programming the brain is complicated by the fact that the programmer (the soul) has to base its code on in formations given by the brain, which might be wrong or distorted. But this limited capability to influence physical behavior seems to be compensated by the mysterious ability to already know what the correct answer to some problem would be like (a kind of "wisdom" that cannot be put directly into words or actions but must be introduced in the brain) and also by the ability to provide (perhaps in cooperation with the brain) a huge diversity of experiences.
Another example can e found in the case of music. We know that there are millions of beautiful melodies out there, but it is difficult to invent them or discover them. It is as if we must go through many random hypothesis until we can find the one that we are searching for. And yet we might already have a goal, although that goal cannot yet be expressed in any terms (nor musical nor conceptual) we already "know" what we are aiming at, although it is a weird kind of knowing since it can't really be expressed, even to ourselves. We will only know that we have arrived at it once we get there. But then, if we are lucky, we may be able to say: «that is what I wanted to express all along, this is it!»
This kind of implicit or unspeakable "knowledge" is what I take consciousness or the "soul" to provide. It is a kind of harmony or coherence or resonance. Once we have all the pieces right, we get this resonance, everything seems perfect. Most of our current machines, computers and so on, need us to achieve this balance. A programmer, a debugger, a user that makes use of the software and hardware. But perhaps someday we will be able to implant this resonance achiever in a machine. Like electrons spinning around an atom, only the coherent "stuff" will be searched for and upheld by consciousness. True empirical theories, beautiful sequences of notes,
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When we try to understand the relation between conscious experience and the mind the first thing that becomes obvious is that there are many things that we feel that we cannot put to words. These things are often difficult to recreate at a later time. For instance, while hearing classical music we may be filled with intense and diverse experiences which no words can recount. But these experiences will often be inaccessible at later times. They are like water that passes by, leaving very few traces that it was once there. One of the most difficult things for the artist or creator, even in science, is to be able to pass to the paper the inner vision that we know we have, although the real job is to become able to describe it, to make sense of it. Many artists have felt that.