That is the first question thrown out by the new UU Salon. "Does it exist before we are born? Does it disappear when we die? It is unchangeable, or capable of growing/shrinking/strengthening? Can you lose your soul, or gain one?" Here is my take, though I'll take the points slightly out of order.
To answer the question, "What is a soul", I need to ask a different question first. Who’s in control of your life? No, I’m not asking if you have an overbearing parent, spouse, or boss, or whether you’ve committed your life to Jesus or to Satan. What I’m asking is, when you speak, who’s talking? If your answer is, "I'm in control of my life," we need to look a little closer.
Do you prefer Ginger or Maryanne? (Or Bob or Steve?) Why? Any healthy body would satisfy instinctive/biological needs. What is your favorite color? Blue? Why? Some have told me it was the color of their favorite flower, but... so what? Why do you like that flower? What is your dream job? What job would you hate to be stuck in? Why? What rational process did you use to choose any of those answers? Odds are, if you keep asking why, your ultimate answer will be, “I don’t know- I just like them.” If you did come up with reasons, I’ll guarantee those reasons won’t bear close examination. All of them will boil down to "I just like that one."
The being who made those decisions- all the important decisions of your life- is the real you, a soul. All those things we think of as "me"- our rational minds, our proud intellects, our conscious selves- are tools the soul uses to manipulate its environment, no different in essence from our hands. The conscious mind does not control our wants, our dreams, our identity- that is why, for example, one cannot decide to be straight or gay. The soul is the "you" who has the answers to all those questions. That soul is who the Divine speaks to.
Some people I've tried to explain this view to have thought that I was saying that the soul is just the instinctive, hard wired, "lizard brain" level of ourselves- but it much more complicated than that. As I mentioned above, there is no biological imperative to preferring Ginger over Maryanne. There is no biological explanation for preferring a red car to a blue one, or the scent of lilac over roses, dogs over cats, rum over (shudder) bourbon, etc.
Does the soul grow? Yes. Although the conscious mind, what we normally call our "self", does not control our behavior, it does influence it. It's a symbiotic relationship; the soul depends upon the mind for its perceptions, its understanding of the world. We are composite creatures, in this respect; we live in two worlds- that which we can see, and the virtual world in our minds. The lowest animals live only in the world they sense around them; higher animals add memory of where they've been, a virtual expansion of their senses. Still higher forms add speculative imagery; they extrapolate what they can expect to find in new but familiar territory. By the time you get to higher mammals, their virtual world is detailed enough to predict cause and effect- anyone who's been around dogs and cats can see them sometimes obviously performing thought experiments, trying to figure a situation out.
But the human virtual world is so complete that we can mistake it for reality. It has been demonstrated that false memories can be implanted by another, or accidentally developed by one's self. Perceptions can be altered deliberately. Take the classic "Is it a vase, or two faces" optical illusion- with practice, one can train one's self to always see it one way, so much so that it now takes an effort of will to see the other. This is how the mind can influence the soul, by changing the perceptions the soul uses to make decisions. I was panicked by a false perception, and countered it with another, in this incident.
It's not just one-time events that perceptions control, but entire lives. People troubled by a conflict between their sexual identity and the instinct to fit in- a powerful instinct; while we were still evolving, it meant life or death- has driven some to deprogrammers, trying to change who they really were. But a change in perceptions- first, that most people don't actually care what one does behind closed doors, and that perhaps it's those who object that are not normal, in that they lack basic human empathy- can help resolve the conflict. Changing one's perceptions of those who disagree with you from enemies or fools to fellow travelers who've had different experiences and perspectives brightens one's spirits and makes one a more persuasive debater in the bargain. Things like this are growth of the soul.
But the opposite can also occur- a bleak outlook can make one ill, physically and emotionally. As I wrote here, "Is life "solitary, poor, nasty, brutish and short.", or is this "the best of all possible worlds", with any hardships being just a foible in a thing of beauty, like getting a flat tire on a Lexus? Both are equally true, for by believing them, you make them so."
"Does it exist before we are born? Does it disappear when we die? These questions beg the question, "Does the soul exist independent of the body?" I don't know that this can be resolved, as the conscious mind that considers such questions is utterly dependent upon the physical shell. How can one have memories from before one had the capacity to form conscious memories? As to surviving after death, one can make a case; we are no more our brains than the word processing program I'm using is the computer- we are software, not hardware, and it's possible that the energy patterns are recorded somehow. I don't spend a lot of time worrying about it. "One reality at a time," is my motto; the Divinity I perceive is not petty or small; if I make myself worthy of this existence, I need not fear the next.
To me, undue concern over an unknowable future in an unknown reality is an abuse of religion. I believe that the proper role of religion is to address the needs of the soul in the here and now... helping one make sense of life's daily absurdities, sharing pain and joy, understanding how to live and how to die.