I was purchasing shotgun ammo at a gun store a while back. The proprietor brought out a box of double-aught buckshot shells which he recommended as having "the power to separate the soul from the body." The proprietor was a 'good old boy,' not someone with whom a wise man initiates a philosophical discussion. But his colorful phraseology got me thinking.
The words 'soul' and 'spirit' carry a cargo of both religious and substance-dualist connotations. And that is the way I will use them. The soul is that in us which thinks in the broad Cartesian sense of 'think.' it is the subject of consciousness and self-consciousness and moral sense (conscience). It is the thinker of our thoughts and the agent of our actions. It is the ultimate reference of the first person singular pronoun 'I' in its indexical use. But I must add that the soul is these things construed as capable of independent existence, as having not only an immaterial nature, but also an immaterial nature capable of existing on its own apart from these gross physical bodies with which we are all too familiar. So 'soul' is a theoretical term; it is not datanic or theory-neutral. 'Consciousness,' by contrast, is theory neutral. If you deny that there are souls, you will be forgiven, and you may even be right. If you deny that there is consciousness, however, then you are either a sophist, a lunatic, or an eliminativist, which is to say, a lunatic. Sophists and lunatics are not to be debated; they are to be 'shown the door.'
A substance, among other things, is an entity metaphysically capable of independent existence. The soul is a substance. It does not require some other thing in which to exist. (Nulla res indiget ad existendum.) So it is capable of independent existence. We encounter it as 'attached' to the body, but it can 'separate' from the body. The question is what these words mean in this context. The problem is to ascribe some coherent sense to them. What is the nature of this strange attachment?
1. Only physical things can be physically separated and physically attached. (The toenail from the toe; the stamp to the envelope; the spark plug from the cylinder; the yolk from the white, etc.) The soul is not a physical thing; ergo, souls cannot be physically separated from or attached to anything. So in this context we are not to take 'separation' and 'attachment' in any physical or material sense, whether gross or subtle. So don't think of ghosts or spooks floating out of gross bodies. Spook-stuff is still stuff, while what we are talking about now is not 'stuffy' at all.
2. It follows from this that every physical model is inadequate and just as, or more, misleading than helpful. The soul is not like the pilot in the ship, the man in his house, the oyster in the shell, the prisoner in his cell. These analogies may capture certain aspects of the soul-body relation, but they occlude others so that on balance they are of little use. But they are of some use. The morally sensitive, for example, experience a tension between their higher nature and their animal inclinations. There is more to the moral life than a struggle against the lusts of the flesh, but that is part of it. Thus the resonance of the Socratic image of the body as the prison-house of the soul.
3. The soul-body relation cannot literally be an instance of a physical relation, nor could it be an instance of a logical or mathematical or mereological or set-theoretical relation. We can lump these last four together under the rubric 'abstract relations.' Presumably the soul-body relation is sui generis. It's its own thing. Just as it would be absurd to say that entailment is an instance of a physical relation, it is absurd to suppose that soul-body is an instance of a physical or a logico-mathematical relation. The soul is neither a physical entity nor an abstract entity.
4. It seems to follow that if the the soul-body relation is sui generis, then there can be no model for it borrowed from some more familiar realm. The relation can only be understood in 'soulic,' or as I will say, spiritual terms. It can only be understood in its own terms. So let's consider mental or spiritual attachment. I am attached to my cat in the sense that, were he to die, I would grieve. Clearly, this is not a physical relation. Whether he is on my lap or far away, the attachment is the same. Spiritual attachment is consistent with physical separation. And spiritual non-attachment (spiritual separation) is consistent with physical proximity and indeed contact.
We allow ourselves to become attached to all sorts of things, people, and ideas, especially our own ideas. Attachments wax and wane. Many are foolish and even delusional. We become attached to what cannot last as if it will last forever. We become attached to what has no value. We have trouble apportioning our degree of attachment to the reality and value of attachment's object. As has been appreciated in many religions and wisdom traditions, much of our misery arises from desire and attachment to the objects of desire. For Pali Buddhism it is desire as such that is the problem; on more moderate views inordinate and misdirected desire. We are also capable of non-attachment or detachment, and this has been recommended in different ways and to different degrees by the religions and the wisdom traditions. There can be no doubt that non-attachment is a major component in wisdom.
5. None of this attaching and detaching would be possible without intentionality. The spiritual self, by virtue of its intentionality, flees itself and loses itself among the objects of its attachment. Chief among these is the mundane self: the body, the personality, their pasts, and the myriad of objects that one takes to be one's own. My car, my house, my wife, my children, my brilliant insights . . . . And now I come to my speculation. The soul attaches itself to this body here in a manner similar to the way it attaches itself to everything else to which it attaches itself. So attaching itself, my soul makes this body here my body. I come to 'inhabit' this body here, thereby making it my body, by my having chosen this body as the material locus of my subjectivity, as the vehicle of my trajectory through space-time. But when" Where? How? I chose this fall into time?
I am telling a Platonic story. I am penning yet another footnote to Plato. Who can believe it? Well, consider the alternatives! You are not your body and yet you are attached to it. What is your theory as to the nature of this attachment? I know what you will say. And I will have no trouble poking holes in it.