I always used to be very interested in what separates what is called the “self” from the “other”. As a child, I used to imagine what it would be like if I had someone else’s mind, like my sister’s or cab driver’s, or what it would feel like to be something I wasn’t, like male or sighted. I used to be surprised that you can say of yourself that you’re a “me”, and that you cannot call someone else “me”, for that’s “you”. I still find this fascinating, and it’s an interesting philosophical thing.
Lately, I’ve become aware of a phenomenon called “natural multiplicity”. People/systems like Astraea and Amorpha discuss this thing. It’s nothing like my “system” – mine isn’t natural and it is by far not as formed as theirs are -, but it’s a very interesting phenomenon. Cause why should people be allowed only one person per body? If we say so, we say that appearance (ie. whether there is a different body) is the borderline between one person and another, while the experience of different people is essentially mental. You can’t say so without having a differentiation between the self and the other, for if you did not make this distinction, what value does the idea of different people have?
Is it an idea? I’d say not. I cannot feel that my sister is “me”, and yet I can feel that I am “me”, and, if you get into plurality anyway, I can feel that the “ladies” are “me”, to an extent (in that their qualities and perspectives should be mine). Some people contend that “the self” is only a linguistic principle, for most verbs require a defined subject, but would you ask who is raining if it rains? I wouldn’t. So I don’t think it’s merely linguistic, even though one can become very detached from oneself when one dissociates.
That still only validates the claim that what we call “self” is a mental experience, not something empirical. And even if it were empirical, that would not mean that it’d be by the existence of a body that personhood is defined. I don’t know how natural multiplicity would be accounted for in the physiological or neurological sense, but we don’t know if homosexuals have any neurological or physiological difference, either.