I agree that establishing it as a fact would require more examination. But I am not making a scientific proposal. I am making a philosophical point which could certainly be taken as a hypothesis.
I think you are blurring the distinction between philosophy and science then. A hypothesis is a scientific proposal.
We all adopt philosophical attitudes, some see a glass half full, some see it half empty. When I am with my children I am a father, when I'm with my parents I am a child, with my boss, I'm an employee. We are all adept at stepping into different personas and that is OK so long as they don't become entrenched or we end up on the road to a multiple personality disorder. It is healthy to recognise that we all have multiple aspects and they all spring from the one source, and so it is with the self, it is useful to think of our selves as something distinct from our bodies, but if you are going down the road of making a scientific hypothesis out of that, that they are ontologically distinct things, then that is going too far into fantasy land for my money; we need to keep our feet on the ground, recognise that ultimately I am one being that is the source of all my different aspects; there is not two me's, my mind is the subjective aspect of my brain; also with my dog, he is one dog, not two dogs with another one living inside, and that spider crawling across the carpet right now, that is one spider it is not two spiders.