Most people who believe in the presence of a soul, also believe that that soul contains some sort of information about who “you” are. They believe that it contains some essence of your self, your memories, your personality.
However, there now exists within the realms of neuroscience, a plenitude of evidence that such a soul does not – cannot – exist (Note: this does not exclude other definitions of soul).
Claim 1: My soul contains the essence of my core personality.
Evidence against it: This one is quite simple. All we have to do to see that this is unlikely is look at brain injury patients. It is irrefutable fact that brain injury can lead to profound changes in personality. Therefore, if one’s personality can be fundamentally changed by brain injury, then one must argue that if a soul exists and contains your personality, then it is also damaged by brain injury. The corollary to this is that if your brain is destroyed, then the soul that contains your personality is also destroyed.
Claim 2: When I die, my soul retains my memories.
Evidence against it: Similarly, many many things can kill the cells (and their network of synaptic connections) that store your memories. Alcohol and substance abuse, brain trauma, etc. Furthermore, there are mountains of evidence that your memories are not static, that they can be changed by suggestion, or changed by time. We have all experienced change of our own memories over time, whether by repetition of embellished stories or simply by memory loss. Our memories lie solely in the physical makeup of the cells in which they are stored, much like digital data on a hard drive (though our own memory storage is much more complex and still being deciphered). Essentially the same argument as above indicates that if a soul exists, it cannot contain our memories, or alternatively, when memories are lost, so too are those parts of the soul.
More Evidence: Everything about what makes “you” you comes from an entire life’s worth of experiences – smells, laughs, people, conversations, traumatic events, feelings, etc. These are all incorporated into your memories, and they help determine your personality. You are not born exactly as you exist today. Your neural pathways, your memories, your reactions, and your emotions are all developed over time, and encoded into the unimaginably complex connections within the 100 thousand million neurons in your brain. Injury can change or erase all of this. Thus, again, if your personality and memory changes, so must the thing which holds them. If your memories and personality die, then so does that which defines them.
All of this does not and cannot rule out the possibility of the existence of some other definition of the soul. But one must wonder: if the soul does not contain my memories, personality or any other characteristics that define my “self”, then in what capacity can I say that any immortal soul is really “me”? Even if your soul lives forever, “you” as you define yourself will be as nonexistent as the brain structures that held “you.”
If brain injury could only delete parts of your personality or delete memories instead of actually changing them, then one might argue that the brain has merely lost access to those parts of the soul – that those parts of “you” are still in there. Many people make this argument - that the soul can only work through the biological machinery that exists, but it still exists independently. But the fact that both personality and memories can be changed suggests that the soul either does not exist, or that it the soul is changed in the same way that the personality or memories are. And if the soul itself is changed, that implies that it is changed similarly by complete destruction of the brain.
It seems that modern neuroscience suggests that any “soul” we contain has no real meaning in regards to containing the “self” as we define it. Thus, any immortal soul we may contain is about as significant as the immortal matter of which we consist. Sure, my energy and atoms might remain for all eternity, but is that “me?”