Plato took a dualist approach about the soul and our bodies, believing that they are both separable; the soul is more important than the body, "the body is the source of endless trouble".
This is because the body is subject to change as it is part of the physical world, whereas our souls are immortal and fixed parts of our identity.
Plato gives the analogy of the charioteer to further demonstrate his ideas: a chariot consists of a charioteer and a pair of winged horses, one white and one black. The horses have to work together for the chariot to progress and the charioteer often has trouble getting them to work together. The white horse represents our soul (spirit), the black horse represents our appetites (desire) and the charioteer represents our reason. The point is that a person should always be led by reason, rather than letting emotions and desires such as lust or hunger get in the way of wisdom.
Aristotle was a monist and believed that the soul, mind and body were all present in the physical world and that they cannot ever be separated.
When the body dies, the soul and mind die too.
In terms of his four causes, Aristotle believed that the soul was the 'formal cause' of the body - the characteristics and attributes of ourselves.
The soul is not distinct but still works together with the body and its nature is dependent on the type of living being in which it is present. For example, the soul of a sunflower has powers of nutrition, growth etc. whereas the human soul has the powers of reason as well as these attributes.
This last point is similar to Locke's principle of individuation.
Rene Descartes was a substance dualist, meaning the body and the soul are separate. This leaves us to question if they are separate then how do they interact with each other?
He argues that the mind is not spatial but is conscious, whereas the soul is spatial but is not conscious.
Similarly to Plato, Descartes believed that when we 'die', the body is left behind but the soul is not. He thought that our souls would be able to continue with God.
Descartes gives the example of a wax candle that has certain physical properties. When it melts, the properties disappear but it is still wax.
After a process of rigorous self-examination, he claimed "cogito ergo sum", meaning "I think, therefore I am".
Ryle was a criticiser of Descartes' dualism. He believed that Descartes was making a 'category error' by suggesting that the soul and the body were separate things because Descartes analyses them as if they are from the same logical category.
To put it another way, he suggests the example of the collegiate university. If one is shown around all of the colleges, the sports fields, the hall, the cafeteria and more, then asks "but where is the university?", then there is a clear misunderstanding of what constitutes a university. Ryle suggests that Descartes makes a similar mistake when laying out his dualism.
"Ghost in the machine" - dualism suggests that a part of us lives on after we die, like an immortal ghost controlling a physical machine until it rusts and breaks irreversibly.
Richard Dawkins is a biological materialist. He argues that the soul is just a concept of deep feeling and sensitivity, and certainly not something separate from our bodies.
Life is simply physical matter and one is just, "bytes and bytes and bytes of digital information". We are "gene machines" made up of DNA and the theory of evolution is the main determining factor of our identity, filtering out all of the 'bad' genes and filtering in all of the 'good' genes.
Dawkins describes the mind as, "a computer made of meat".
There is no soul that continues after death, only our genes that are passed on through reproduction before we die live on.
The idea of the soul is 'wish fulfillment' from religious believers who lack courage or fear death. For Dawkins, we have no reason to fear death because it is a basic experience where our consciousness ceases to function.
Replica theory - when we die, an exact replica of our bodies is created and transported to heaven by God, using copies of each exact atom.
Hick believed that we consist of matter alone but he was also a believer in God and a Christian, "there is no 'ghost in a machine'. All that needs to be said about us can be explained by reference to our physical selves".
It could be argued that even an exact replica isn't the same, this criticism is known as the branching problem. A replica in heaven will get new experiences and have memories that the earthly man didn't and so Locke would argue that they are the same man but different people.
The body and the soul are inseparable. Therefore, if there is to be a life after death for the soul, the body has to be resurrected.
Locke is by far the most interesting to study out of all the scholarly views. He argues that identity means being one thing and not another i.e. two distinct individuals cannot be in the same place at the same time.
He puts forward a principle of individuation (POI): substance (our matter, atoms etc.), man (the living organism) and person (our reason; a rational being). A living tree would have substance and man but not person.
Most living humans would have all three; a severely disabled man with no more conscience than a vegetable would have substance and man but not person.
For inanimate objects, personal identity is different. E.g. if you chip a piece off of a rock then it becomes a different rock, however, if a living being such as a tree or a person lost a branch or their hand then they are still the same thing and have the same identity.
Locke concludes that memory/ consciousness is the key factor for personhood. Example of DayMan and NightMan.
There are plenty of objections to Locke's ideas:
Memory - loss: most of us lose entire chunks of memory and Locke bites the bullet and says yes that does mean we are different people even though we are the same human. This can be illustrated by the Breakfast Problem.
Logically flawed: Shown by the Brave Officer Problem (Thomas Reid), If A=B and B=C then A should = C.
Punishing the drunkard: the fact that we often punish a sober man for the crimes he committed whilst drunk shows that they are the same man and the same person, even though the sober man cannot remember committing the crime. Locke responds that they are not actually the same person and strictly speaking it is not fair to punish the sober man for the actions of the drunkard. I would respond by saying that it is fair because the sober man made the conscious decision to get drunk in the first place, but then again, choosing to get drunk is not the same as choosing to commit a crime.