Warning, this may get pretty esoteric. I’m presenting a traditional viewpoint, normally I’m not a fan of parsing out words this way:
Here are the words used in Hebrews 4:12
psyche – soul
pnuema – spirit
Psyche implies the soul as the seat of feelings, desires, aversions and the eternal essence of a person that is not really a part of the body. It continues after the body dies.
Pnuema implies the vital principal by which the body is animated
So, Hebrews 4:12 can be read, it (the Word of God) penetrates even to dividing heart of a man (seat of feelings, desires, aversions, etc) and spark that gives that man life.
Then again, sometimes these words are used interchangably. Thinking that way, the verse can be read that the Word of God can separate those things that appear inseparable. (Thereby making it discerning and penetrating).
*************
Having said all that, I have always interpreted this verse to mean simply that the Word of God is able to get to the root of the matter very quickly. Applied correctly, it removes pretense and side issues to address what is really going on.

That was quite the timely response.
I pulled this out as your definition:

Your soul is “who” you are, your personality, everything that makes you uniquely you.

For a think to be a soul, you list three criteria: it must exist, it’s a personality, it is unique. Well personalities certainly exist, personalities are, um, personalities, and personalities are unique. Thus you’ve simply re-labeled ‘personality’ as ‘soul’. I have a personality (that some find disagreeable) thus, by that definition I have a soul. Of course, by that very same definition, many animals have souls as well.
To this definition, you’ve attached traits, including: permanence and God-given. I’ll argue against the former.
Personalities can change after brain damage, sometimes quite drastically. They can be severely altered by chemicals as well. This suggests that the soul is damageable or at least alterable by physical things. Personalities are also not present during unconsciousness. Finally, personalities have never been shown to be expressed after one’s death. This gives me strong reason to doubt that my soul/personality is eternal.
Furthermore what I identify as my personality or myself is a process, not an entity (physical or otherwise). This process depends on the proper functioning of my biology. As an analogy, my personality is like a computer program: it’s something that matter does. A program cannot run on nothing. More reason to doubt the permanency of the soul as you’ve defined it. Another analogy would be music. Music is something that instruments do. If there are no instruments and no voices, then there is no music either. Since all computers and instruments are not eternal, neither are the things they do. Similarly, since my biology is temporary, so is my personality.

I understand the point you are making about the biology of the soul. It is similar to this
http://www.thefreelibrary.com/Biology+of+the+soul-a015922720
One of the things Richard Goss brings out in his paper is that some matters are extremely difficult to discuss from a scientific basis.
He touches on the idea of ruining beauty by analyzing it. Yet he continues on by saying that the noble pursuit of truth should outweigh any loss.
I would posit that in the history of ideas, the concept of the soul was formed to give a name to an ephemeral part of a human being. What do you call the part of a man (which appeared at the time to be non-biological) that encompasses feelings, desires, affections, aversions, etc. Even if the soul can be reduced to a series of self-governing metabolic processes, there is some necessity to make a reference to this idea.
The soul is a philosophical concept that is not rooted in biology. As such, it is a non-sequitir to approach it through biology. It is the same if biology is addressed from a philosophical perspective. The soul is a handy label to describe what might be called a psychological phenomenon.
I am aware that my belief in an eternal soul has the appearance of superstition. Yet if a thing cannot be proven either way, it comes down to a choice anyway.
On a slightly different topic, when you speak of music and instruments, it depends on certain rigid definitions of both. The only real way that music could not exist is the nonexistence of everything else. To wit, an empty bottle makes music in the wind. The more effort is placed into removing the cause of a note being sounded, the more things are obilterated. Even if all objects are removed it will exist in memory. Music exists as long as life exists. When all life ceases, it is a moot point.
Granted, I do not think there is a way to prove if the soul is eternal or not. It really cannot be proven one way or the other.

That is an interesting question Scott..
I guess I am happy to simply say that there is an inner and an outer being. The inner being is what Jesus is speaking of when He speaks of being born again.. in a sense this is being spiritually reborn on the inside.
I agree with what Sid said about the personality not being eternal.. I would classify it as a part of the temporal outer being.
I agree that there is not a way to empirically prove whether the inner man is eternal or not.. unless you accept what Jesus spoke of in the scriptures.. He is empirical enough for me.. just kidding.
I sometimes think that life is a battle between the inner and outer being.. it seems that the stronger being usually wins. One of the reasons I think that it is important to feed and exercise our inner being.
When we are weak on the inside (call that spiritually or morally weak) we find ourselves giving in to the immoral desires of our outer being.
See you guys later.
Bob

“Personalities can change after brain damage, sometimes quite drastically. They can be severely altered by chemicals as well. This suggests that the soul is damageable or at least alterable by physical things. Personalities are also not present during unconsciousness. Finally, personalities have never been shown to be expressed after one’s death. This gives me strong reason to doubt that my soul/personality is eternal.”
I don’t actually agree with what I’m about to say, and you’ll see why, but I’ll make the argument that I think would typically be made against these. To respond to all three, I will simply say that the soul is not in this plane of existence. Certainly, we don’t see souls floating around the world. That’s because they don’t physically exist. However, if they existed in a realm or state other than this one (I’m not going to define how, which will become a problem later on), then I can say that the soul is a manifestation of a “person” that contacts the body in this world. Thus:
Argument 1: Brain damage and chemical effects only affect the physical body through which the soul “communicates,” not the soul itself. The personality that is affected is the soul as expressed through the body. The soul is not affected by things in the physical world, thus it remains unchanged. It’s as though we were speaking through a microphone that suddenly starts crackling or warping the sound of our voices. Our voices themselves don’t change, just the vehicle through which the voice is sent.
Argument 2: Personalities, insofar as they come from souls, still exist during unconsciousness. They just aren’t expressed by the body. Thus, this is just like 1.
Argument 3: Again, the personality as soul + body is gone, but personality insofar as it is housed in soul continues to exist.
The problems with the above argument are, among others:
1: How does the soul affect the body? if the soul is in a different “form,” “realm,” what have you, you are led straight into Descartes’ dualism (mind/body) problem. (And no, you can’t claim the pineal gland to get past it.)
2: If the soul is not in the physical realm, just where is it? In what sense does it “exist?” Can I talk about “existing” without using quotes to tell people ahead of time that this manner of existing is completely unclear? If it is in this realm, how? Again, how does it “exist?” And can’t it then in some way be effected?
3: Another problem with positing another world: If you can posit another world, so can I. I posit a world with tiny pink elephants riding house-sized SUVs. Is that less justifiable than the realm of souls? Neither is physically present in the conventional understanding. One might say, “Oh, but we can see the soul’s effects.” But that’s begging the question; we are assuming that it is souls that cause those effects and not natural causes.
All of this is a quick sketch of what comes up when you talk about “souls” as such. If you talk about souls in a different sense, not necessarily as existing entities but as some sort of complex, or a general reference, or a figure of speech, you enter wholly other grounds.

(Disclaimer: the reason I’m writing so much here all of a sudden is because this is part of a broader line of thoughts about the nature of faith I’ve been considering for a while, and this is a chance to clarify in my own thought. Feel free to just pass over and go on with your day, especially if you feel it’s going off topic.)
“I think that the soul exists in this plane of existence. We can’t see it, measure it, dissect it and thus I can’t really explain how it exists. That’s where faith enters for me. And yes faith means that we will inevitably start talking about “well why can’t I believe in pink elephants/fsm/unicorns and isn’t that just as valid”. Different argument.”
What makes it a different argument, though? How does faith enter into your belief in the soul? If faith (to take the most generic definition) is simply a matter of belief without proof, then it does go straight into the other consequences mentioned. This is because we need some way to say that one belief is better than another, but we’re not defining a way to do so. Why is faith in X okay, but not Y? What’s the difference? The moment we ask that reasoning and argument into the picture, and faith loses the definition we gave it (or you can go the other way and say we’re no longer in a state of faith). Faith in that sense isn’t sufficient, as it lacks any reasoning to choose one faith over another besides the purely subjective, which leads to the problem of pink elephants.
Of course, the above definition of faith is very simplistic. Faith is a complex concept with a long history, and frankly I myself don’t buy the above definition. But if you define faith as something else, what is it? And how does it relate to belief in the soul? Does it support that belief, and how?
Something similar can be said in regards to our understanding of physics. No doubt current physics does not explain everything it could, and there may be things it simply cannot explain no matter what. So if we want to make an argument about the soul that is justified, then we may call contemporary physics inadequate. But what then? (And I study philosophy, so I am familiar with other forms of proof, but what I am familiar with about the soul I object to as well, for various reasons including what was said above. And generally speaking, current philosophy does not claim to justify the soul unless you go into philosophers coming from a specifically religious position.)
Now for all teh above, one can simply say that he or she not interested in justification, but (and here’s what I’m really getting to) I’m not sure that’s really the case. If no reason at all is held to believe X or Y, that literally means there’s no reason given to choose one possibility over another. But given someone believes X and not Y, that would mean they should be just as willing to believe Y and not X. Yet this is not the case. The person believes one and not the other. If this isn’t the total independent whim of fate/chance, there must be a reason, yes? If that person holds to that belief for any reason, against any objection, even the slightest questioning about it, there is a reason for continuing belief in the face of challenge, be it logical, empirical, unconscious, biological, or otherwise.

I might suggest you read Tillich’s “Dynamics of Faith.” It’s short and offers a definition of faith that might be of interest to you. I won’t go into details, but for Tillich, faith is sort of a state of being. It’s not about what specific things you believe and how, but more about how that which you have faith in affects and influences your existence as a person. He calls faith a state of “ultimate concern.”
From what you’ve said, I’d be tempted to put you more in that direction rather than as thinking of faith as being simply about belief. The thing is that, as Tillich notes, this change in definition means we should stop talking about it in terms of logic and reasoning. So, for example, perhaps you can say that faith makes sense for you, but it introduces confusion to call it logical in the same sentence.
Let’s take it back to the original topic: what is a soul? It could be an entity, subject to proof. Or, it could be part of one’s conception of the human being, that with which one communicates and which one cares for. The second definition isn’t subject to proof in the same sense as the first one, because it’s meant in an entirely different sense. But it has to be distinguished from arguing that the soul exists but is not subject to proof given our capabilities. In the latter case it becomes a matter of reasoning or logic, and then we’ve lost Tillich’s definition. I think that’s part of the confusion here. Do we want to think of “soul” as a thing which exists or does not, which can or cannot be proven, or as something which we care for, which is each one of us? The two don’t mix, as one is about claims about the existence of a thing, and the other is about how we experience. Yet, the two often get mixed up, with the result being a subjective investment in a matter of objective existence. We might start talking about the “properties” of souls, of what realm they exist in, and so on. But at the same time, we still think of the soul as that which makes a person a person, as the center of being, who we’re familiar with, etc. and want to defend it. But they’re two different senses.
To finally get back to your post, then, what you’re saying makes sense to me when I think of it as Tillich did. Christianity, God, the soul, etc. are part of a worldview that gives the things and experiences in your life a particular significance. They make sense of things in the sense of building a coherent whole around which your life works. But if we think of it like that, I would say it’s erroneous to talk about those topics as subject to proof: not only in the sense of proving them, but also as existing or not existing, being right or wrong, or any sense of objective reality. Otherwise, you get into discussions like this, where one side has a purely objective discussion in mind, and the other is working to prove something that ultimately “exists” in a personal sense. You can see the concern this brings up: does that mean we have to assume that God, souls, etc. don’t exist? That, ultimately, is answered by how you view the situation.
Finally, what do I think a soul is? An individual human personality. What has inclinations, a nature, and an existence in a single person. Not, however, something that “exists,” per se.

Sid:
I think I might have a response to your alcohol argument, provided one loosens up the dualistic nature of this whole debate a bit. I think you’ll agree that, if you were to assume a soul, a large portion of our experiences would still require bodily sense to actually be experienced (for example, a soul without sense experience cannot actually see light in a sensory manner). I could apply this and argue that, by affecting the body, alcohol in fact alters that which the soul requires for much of its experience. Your soul may not literally be drunk, but if the sensory faculties we use to experience are necessarily sensory experiences, then the effect on the soul’s experience will be the same; namely, you will feel drunk. In other words, your “subjective experience” is in this case bodily experience, soul + body.
However, this means that the body has some degree of control over what the soul experiences, and is even depended upon in some cases. That seems fine to me, but perhaps not to others. Also, no doubt some would claim that the soul can have sensory experience, or something like it, without the body. That’s a tricky one, and I’d have to ask how they intend to defend it.
As to this:
“How is this not pure relativism? What basis does one have to value things in faith X as opposed to faith Y. It still means there is no criteria for rejecting pink elephantism nor for accepting souls.”
I think you’re absolutely right (note that in the start of that paragraph I essentially said, “assuming this…”). Not only that; it’s basically what I was talking about in the post prior to that. This is because you and I think in terms of justification-based systems of belief. For me, a completely different type of faith, like Tillich’s “ultimate concern,” is interesting primarily as an anthropological concept. I find it interesting for describing human nature and experience. But I would still say that accepting it as the “proper” way to view the world and truth leads to complete, total, absolute relativistic consequences, and in the last paragraph a couple of posts up, I argue that virtually no one would accept that. Thus, using “ultimate concern” as a way out fails. I rather jumbled it up by implicitly criticizing Tillich before I actually used him, but that last post was a bit different in nature.

Coming in late to the party (and admitting to not having read all the comments), I wanted to say that the idea of when the soul enters the body, and by extension leaves it, is intriguing. I think it can have profound effects on big societal questions like abortion and when we let go of those who have long been ‘brain dead’.
To me ths soul is the essence of me, its tied to this body but yet distinct from it. It’s intertwined with my personality, but it is more. To me, it makes a lot of sense that the soul entering the body defines the beginning of life, then again I wouldn’t say my cat has a soul but it is alive.
Complex issues.
The other thing I wanted to point out is that Doug the attorney at salguod.COM may have an opinion on his, but I doubt he’s aware of this conversation (unless he checks for links to his page regularly). This Doug, from salguod.NET, finds it interesting however.