Hi Telofy, nice to hear from you again :)
You say that you have no intuition for what a subject-of-experience is. So let me say two things that might make it more obvious:
1.Here is how I defined a subject-of-experience in my exchange with Michael_S:
“A subject of experience is just something which “enjoys” or has experience(s), whether that be certain visual experiences, pain experiences, emotional experiences, etc… In other words, a subject of experience is just something for whom there is a “what-it’s-like”. A building, a rock or a plant is not a subject of experience because it has no experience(s). That is why we don’t feel concerned when we step on grass: it doesn’t feel pain or feel anything. On the other hand, a cow is a subject-of-experience: it presumably has visual experiences and pain experience and all sorts of other experiences. Or more technically, a subject-of-experience (or multiple) may be realized by a cow’s physical system (i.e. brain). There would be a single subject-of-experience if all the experiences realized by the cow’s physical system are felt by a single subject. Of course, it is possible that within the cow’s physical system’s life span, multiple subjects-of-experience are realized. This would be the case if not all of the experiences realized by the cow’s physical system are felt by a single subject.”
I later enriched the definition a bit as follows: “A subject-of-experience is a thing that has, OR IS CAPABLE OF HAVING, experience(s). I add the phrase ‘or is capable of having’ this time because it has just occurred to me that when I am in dreamless sleep, I have no experiences whatsoever, yet I’d like to think that I am still around—i.e. that the particular subject-of-experience that I am is still around. However, it’s also possible that a subject-of-experience exists only when it is experiencing something. If that is true, then the subject-of-experience that I am is going out of and coming into existence several times a night. That’s spooky, but perhaps true.”
2.Having offered a definition to Michael, I then say to him here is WHAT MAKES a particular subject-of-experience the numerically same subject-of-experience over time:
“Within any given physical system that can realize subjects of experience (e.g. a cow’s brain), a subject-of-experience at time t-1 (call this subject “S1”) is numerically identical to a subjective-of-experience at some later time t-2 (call this subject “S2“) if and only if an experience at t-1 (call this experience “E1”) and an experience at t-2 (call this experience “E2”) are both felt by S1. That is S1 = S2 iff S1 feels E1 and E2.”
Let me just add: A particular subject-of-experience can obviously be qualitatively different over time, which would happen when his personality changes or memory changes (or is erased) etc… But that doesn’t imply there is any numerical difference. I assume the distinction between numerical identity and qualitative identity is a familiar one to you. In any case, here is an example to illustrate the distinction: Two perfectly matching coins are qualitatively the same, yet they are numerically distinct insofar as they are not one and the same coin.
I hope what I have said here helps!