The idea of soul
It is merely a delusion
The soul is a figment of the religious imagination.
Christianity, to take just one religion, teaches that human beings — and only human beings — possess something called a “soul”. However, simply by the evolutionary continuum hypothesis, the concept of a soul unique to humans is so unlikely as to be meaningless, unless it arises from some property unique to the human species and I know of no evidence to suggest such a step change in the fundamental makeup of this species as compared to the closest relatives, the higher primates.
The monotheistic religions explain the soul as being there because of direct action by YGA, in other words interference in his creation at the moment the modern human species emerged from the process of evolution. At least, that is the form the story takes for those who accept evolution; but the creationists reject evolution anyway, and think YGA did every little bit individually himself.
Those religions all regard the soul as a separate entity from the body or the mind as that term is understood by them; I reject their position completely. I can see no empirical basis whatever for a hypothesis that such a thing as a soul exists; I therefore regard the idea as a human invention, however often it is borrowed from the priests and theologians by poets and artists, based on a self-aggrandizing need to pretend that the human species is somehow definitively superior to the myriad other species on this planet. However nice the idea that we are special and different from “the animals”, it is evidently mere invention. In my view, that which anybody except a priest using the term calls the soul is simply a subset of the mind, a generalized aggregate view of brain function.
Brain, mind, heart, self
The heart may have a small information storage capacity but that can safely be considered merely an adjunct to that in the brain and the rest of the nervous system. When poets, romantic novelists, movie screenplay writers, and religious people talk of heart in non-cardiological contexts, what they are referring to is a subset of the functions of the mind.
The mind is simply the aggregate of activity of the brain (taken together with the nervous system and any other information-storage capacity in the body).
Consciousness is simply the phenomenon by a which in a mind sufficiently complex,
possible because it is the functioning of a brain sufficiently large (in
storage and processing capacity) to have the bandwidth for this,
there arises a function (a process that persists long-term,
with an established purpose) the effect of which is to watch the other
functions of the individual organism and some subset of the rest of the mind itself;
that is, thought processes exist of which the subject is (i) those thought
processes themselves and (ii) other thought processes within the same mind.
Quite how this happens has been a matter of intense attention, speculation, research and much writing
for a long time, and yet it may indeed still not be fully understood; however
there is no reason of which I am aware to suppose that there is anything mystical,
or other-worldly, about the phenomenon. It is simply a by-product of huge extra bandwidth,
that is, above the level found in species that do not have self-awareness,
and it quite possibly evolved for perfectly credible reasons
such as those surmised by Dawkins and others in their work.
In this context, self means nothing more mysterious than the individual lifeform, specifically (for the time being) a member of human species, as perceived by that lifeform's own mind and referenced most commonly in human language by some particle which in English is one of the first-person pronouns (“I” and “we”).
The mind does not exist in a software vacuum. Obviously there are the physical senses which supply information, and there is the nervous system reporting sensations including pain. There is also the endocrine system, and the whole complex business of brain chemistry, which interacts both globally and locally with the individual units of the brain that implement the mind. A major effect of this aspect of human physiology is the effects of the endocrine system activity on mood and hence on the varying strength of the tendency of the mind to harbour thought processes about particular aspects of life. All of that is well known; but it is important to remember that a lot of the specific moods that some states of endocrine system activity can provoke are closely allied to “states of mind” that people of a religious or poetic turn of mind equate to involvement of the “soul”. It is still utterly spurious.
YGA: Yahweh or God or Allah