Determinism is a belief which I have touched upon in the past, but I didn't go into massive depth on its criticisms, specifically that of a 'soul'.Determinism is the view that all events occur because of previous stimuli or circumstances which led to their happening. Consequently, determinists believe that nothing happens without a reason.

Don't misunderstand this, just because they believe there is a reason for everything doesn't mean that they are able to see or prove the reason exists, nor do they believe there must have been some original creator with their own intentions for the universe, although some certainly think that it's possible for determinism and religion to coexist.
I wrote a blog on it a while ago, click here for more depth on the subject.

The issue with determinism is the unpleasant conclusions which can be drawn from it. Soft determinism is the belief that, while things do influence each other, they are not 'set in stone,' and it is always possible for events to have gone either way.
Hard determinism is the belief that every single event and circumstance, including the human mind, are totally determined by every factor prior to its occurrence.

Soft determinists usually like to cling to the idea of free will, their main defense being the insistence of a human 'soul,' saying that there are certain elements of the brain which are not dependent on deterministic factors and don't obey the usual laws of physics.

There is also the 'quantum randomness' argument, however that is insignificant to their cause, for reasons I will explain later.

For the most part, let's focus on the soul argument. Well, I say "Let's focus" as if you really have a choice. I mean, I'm the one writing the blog here, it's not like you have any say in the matter.

The word 'soul' is pretty ambiguous. It's not very clearly defined, and it's ssible to coherently criticise something with no clear definition, so for the purposes of this blog I'll say what the definition of 'soul' will be.

A soul, for the sake of this blog, is the part of the human mind which has free will. This is as opposed to areas which deal with bodily functions, automatic processes, hormones and movement and the like. I specify 'human mind' since some argue that the soul exists in a separate plane or dimension to the body, or something like that.

Now that's out of the way, we can move on.

The main argument of the existence of a soul, and consequent existence of free will, is that the soul exists separately of the laws of physics, being some weird supernatural thingy which doesn't play by the rules.

While this does seem like an irrefutable argument, or at least impossible to disprove, that's not necessarily the case. It's a well known fact that one of the most important laws of physics is that matter and energy can neither be created nor destroyed.

If we make an arm movement, we can trace it back to its origins in our brains. We know that it was caused by an electrical impulse originating in the brain, which was transported to our muscles via a nerve. Electricity is a form of energy, we know this, and we know how muscles and arms work. All totally physical stuff, nothing supernatural about it, right?

Now, this begs the question as to what part the human soul plays in this. If we moved our arm out of our own free will, and not out of instinct, a soft determinist or indeed someone who totally rejected determinism might say that, while it's true events may have influenced our decision to move our arm, we weren't determined to move our arm. Had the same event occurred multiple times with precisely the same circumstances, it's possible that we could make different decisions.

Since this deals with free will, there must have been some involvement from the soul.

We can trace the movement back to certain areas in the brain, so clearly the point at which the soul intervened and made a decision must be the point where we can no longer determine a cause for our actions. Hard determinists would say that, if we were technologically advanced enough, we could build machines capable of observing every single relevent factor in the decision, and there would be no point at which we couldn't explain their decisions.

Clearly we don't have such powerful computers yet though, so imagine, for a moment that there came a point at which we couldn't find a cause for a certain impulse. That must be the point at which the soul intervened, right? The soul must have sent an electrical impulse into the brain, which travelled down your arm and made it move?

But that means the soul just created energy, from nowhere. The soul is supposed to be immortal, needing neither energy nor maintenance in order to operate, so it neither has nor needs energy of its own. If we are to accept that the soul played some part in this decision to move your arm, where did the energy to signal the arm come from?

Another criticism of the soul is the clear evidence of links to the conscious mind and the physical brain. There was a famous example of a man who was working on a railroad and got an iron rod blasted through his skull, taking a decent chunk of grey matter with it. He survived, but was an irritable and unpleasant person from then-on. The iron rod, as the surgeons had discovered, had torn through the part of his brain associated with behaviour, and he constantly had a radical change in mood and actions.

It's clear from this and numerous other cases that the brain has an incredibly important role to play in our thinking and conscious thought. People who are born with brain damage are sometimes slightly retarded or incapable of coherent thought, making decisions that no normal person of their age would make.

So what part does the soul play in all of this?

One argument would be that, while the mind is dependent on the soul, the soul is also dependent on the mind. They are linked, and consequently if one is damaged, so is the other. While it seems queer to think that something as strange and supernatural as a soul might be linked to something physical like the brain, since it's already exempt from the laws of physics by its very nature, it's not entirely out of the question that it does, and we simply don't know enough about the brain to realise it yet.

However, if you believe in the soul and you also believe that the soul goes to heaven or hell or whatever afterlife you believe in, then isn't there a pretty big flaw right there? If the soul is damaged by brain damage, then wouldn't it be killed by brain death? After all, what can be more brain damaging than death? So how then can it continue to exist independently of the body if the brain has been crushed by a car compactor or run through an industrial shredder?

You could, of course, pull the 'God is exempt from logic' card, which is either the best explanation for everything or the ultimate cop-out for when you're backed into the corner in your argument. Essentially, if God is all powerful, then absolutely nothing can limit him, and surely he has the power to defy logic? If he can defy logic, then it's absolutely impossible to disprove anything he says, simply because any logical flaws which are found in the arguments can just be blamed on God being illogical, and not a flaw with the argument itself.

Some also might argue the 'quantum randomness' thing mentioned earlier. They'd say that, on a quantum-level, there is a chance of matter spontaneously popping in and out of existence for incredibly small lengths of time, and many sub-atomic particles are thought to act totally randomly without any kind of motivation. There's always the chance that we simply don't understand them enough yet and there is some kind of a cause, but we've yet to find evidence of one.

However, this argument is entirely invalid when arguing for free will for two reasons. Firstly, such quantum events are quantum, and consequently incredibly small. Ridiculously small. The chances of them creating any kind of change on the scale the human brain works on are insanely small. So small that, frankly, there isn't much point in considering them.

Secondly, even in the case that something were to occur randomly on such a level which actually influenced events on a larger scale, it would not be proof for free will. Something totally random is not free will. It makes absolutely no difference, and if anything works against the case for free will.

And so you get to ponder over another load of my pretentious ramblings under the guise of philosophy. Consider thyselves educated.