I've seen people moving and breathing after their "soul" has left them. My former good friend Dave had a heart attack and suffered massive, irreversible brain damage. What's left is certainly no longer Dave- although he can speak, he utters nothing but automatic commonplaces. He has no discernible interest in the world around him, and if you don't prompt him, he never initiates a transaction.

Memory's Ghost, by Philip J. Hilts, is a very good book to read on this subject- it concerns a young man whose hippocampus had been deliberately removed in an attempt to cure his epilepsy. Although he lived many years after that, his only knowledge was of the period prior to the operation, and the few seconds preceding the preesent moment.

Many people here want the soul to be a tangible, detectable thing, but I believe that it is a process of the brain, like the software of a computer (I'm not saying it is exactly like current computer software). Have you tried weighing your computer before and after installing software? Probably no, you know that there will not be a difference, as it is merely a rearrangement of states of magnetic domains, or electrons moved to different places in logic gates.

The brain of course is dynamic, and grows and shrinks physically, but the "soul" is the rearrangement of states of the organ, and can grow, shrink or depart completely without any detectable change other than in the behaviour of the whole organism.

So I'm quite happy to talk about the soul, though I would not normally choose to, as it is so easily misinterpreted- during life, it has all the attributes of the soul of religious belief, including temptation, possession and even a guardian angel- but these are all generated within or acquired as memes from without. As a process of the nervous system, it has no existence independently of the organism.