I think it's just a fact that like Descartes did, most of us think the subject of "I think", "I have an idea", "I had second thoughts", etc. as the mind not the body. However, it would be wrong to equate the notion of mind here with a religious concept. I believe that mankind went through its first millenia without paying attention to its mind very much. It's only gradually that the notion we had a mind took shape. The religious view of it came an a mere extension of the original notion. Removing the extension still leaves the original impression that the subject of thinking is not the body.
EB
You may say this is simply a matter of semantics, but I see it as inescapable that if I
have something then it is in some way a part of me, and yet I am not that thing. I have thoughts. I have a body. But neither is me. I as a person have relationships and material possessions which partially define me. I am not one thing but the focal point of all these things.
I agree it's possible to look at it this way. This would be somewhat similar to the idea of particular things as the bundles of their properties. Yet, this seems a very abstract way of considerering things, which makes me think that it's not the way most people see it. It's a nice theoretical perspective but it's not what we do in actual fact, at least as far as I can tell.
There's another fact, it seems to me, which is that sometimes we talk as if the subject is not our mind at all but our social persona. When you have an appointment, you must be very aware that people expect to see you in person, not, say, talk to you through a telephone line or something. Meaning that your linguistic tics may have functional significance but that they need to be put into context to be properly understood. Your explanation is probably good for talk between scientists or philosophers, but that doesn't change what most people do most of the time because it's just the way it works. I'll let the better psychologists to explain why we tend to speak like this.
It seems even when it comes to the mind it is the sum total of the various functional parts of the brain. The self is not a physical or spiritual thing. It is not ontological so much as it is epistemological. Its a model created by the brain. The more we strive to describe the self or the mind the more plainly this is shown to be true. Philosophers argue about the nature of reality and whether it exists "out there" or only in the mind. Well this is one case where the model we create only exists in the mind.
I will grant you that many sciency types like to talk as if it was just dumb to not assume that we have a brain and that it "does" the mind. First, my point was that the perspective of mind-as-subject seems to be the default position for most people, since forever, not that our mind wasn't in need of a brain. Second, I'm not sure why the idea of a brain should be taken as particularly noteworthy. Personally, I believe that the way my mind is effectively required the whole universe to have been a certain way during its long history. My brain, if I have one, I'm quite sure couldn't do whatever it's doing without the rest of the universe to cause it to do what it's doing. Third, personaly I don't actually know that I have a brain whereas I know that I have a mind, in the sense given by Descartes. Fourth, it's clear to me that if however talk of "my brain" was somehow correct this notion of "my brain" would remain an image I use to make sense of things. I don't really believe that I have something like an actual brain.
ETA:
I hold Plato and the Neo-Platonists responsible for promoting the idea that this system of understanding requires an absolute existence where symbolic reasoning requires an idealized spiritual realm.
Epicurus had it right:
Epicurus emphasized the senses in his epistemology, and his Principle of Multiple Explanations ("if several theories are consistent with the observed data, retain them all") is an early contribution to the philosophy of science.
"There are also some things for which it is not enough to state a single cause, but several, of which one, however, is the case."
I'm not sure how Plato's views relate to what I said. I take it that your view of the subject as the focus of whatever "we" have may be an alternative to Platonic Ideas but you may have noticed that I take an epistemological angle as well, and it seems to me that Descartes also derives his ontology from his epistemology, at least when it comes to the issue of the mind.
EB
).