As a neuroscientist I don’t believe people have a soul, ruh, jiva, atman, or whatever you like to call it. Instead I believe all things are in a constant state of flux: all is ever changing, and no permanent state exists by itself. In my opinion, there is no eternal soul, or permanent “self”, that in one way or another is connected to an eternal being (god). And I believe this applies to human beings as much as to anything else in the cosmos. Thus, a human being has no permanent self, and the words “I” or “me” do not refer to any fixed thing. They are simply convenient terms that allow us to refer to an ever-changing entity. But, at the same time, I’m not a total materialist, who thinks everything is physical. The mind-body problem is still unresolved.
But as much as I sometimes would like a “soul” to be an incorporeal component in living things that can continue after death, there is no proof of such a entity. We know from neuroscience and psychology that memories, emotions, desires and the rest are issued from the brain, and there can be no physical connection between the soul and the body, since the soul apparently is not physical. Neuroscience argue further that it is empirically necessary that we have a functioning brain to have consciousness. But at the same time, we don’t have any examples of ‘mind or consciousness’ as a separate part of the brain(organ), which is kind of confusing. But, none the less, drugs, illness, and damaging the brain(organ) will undoubtedly cause an altered level of consciousness (which could be said to be a weak argument, since e.g. PC damage does not negate a user). So we really don’t know what this “self” is, but we do know it is dependent on the brain. At the same time, I don’t think we are biological robots in a material world. And any honest scientist or philosopher will tell you that the relationship between mind and matter is still a mystery, perhaps our greatest mystery.
In buddhism, which denies the existence of a permanent entity that remains constant behind the changing corporeal and incorporeal components of a living being, they believe that, just as the body changes from moment to moment; thoughts come and go. And there is no permanent, underlying mind that experiences these thoughts. Rather, conscious mental states simply arise and perish with no “thinker” behind them. There is no thinker behind the thought.
Some buddhist believe that when the body dies, the incorporeal mental processes continue and are reborn in a new body. Like old software in new hardware. But since the mental processes are constantly changing, the being that is reborn is neither entirely different than, nor exactly the same as, the being that died – the new being is more like a continuous with the being that died. In a way it could be related to a persons personality or mental state, a “you” of this moment is continuous with the “you” of a moment before, despite the fact that you are constantly changing. I really don’t know which one is true. And even if there is something called reincarnation, rebirth is in essence irrelevant because, even if it does exist, it can never be consciously experienced. So, psychologically, it is a phenomenon without relevance. But biologically, I know I am the continuation of my father and my mother.