I would have to say it's assumed... Assumed on the basis that I cannot conceive of a decision without a decision-maker andy more than I can conceive of a watch without a watchmaker.
Does the heartbeat or the growth of the body require a controlling/managing entity to make it happen? Perhaps when you're doing tasks that go without much thinking, like eating, driving, cleaning, just relax, let it happen and just be with the question 'is there a separate doer doing this?', or perhaps 'is a separate self necessary for this?' or phrase the question a way that resonates better with you. No need for jumping to conclusions, arguments or such there.
But if it's obvious and inescapable - why am "I" not accepting it?
What may be useful is if you write down what the person/self is to you. Just statements that feel true, like 'I feel like I'm a separate entity/person, that's separated from everything outside the body, that's going through life and perceiving everything around me', etc.
Okay, I think I've given an exercise concerning seeing and feeling once. Perhaps it's good to finish it with hearing. So I copied pasted the exercise underneath. Afterwards we can take this further with the intention of loosening the notion of there being an in- and outside a little further. I think that might be useful.
Normally we say something like 'I hear a bird/sound,etc', so, let's explore that. There are 3 assumptions there;
1. the I that is doing the hearing
2. a process that is happening we call hearing
3. a thing that is heard
So relax, sit down or whatever works for you, close your eyes, notice the sounds that are going on around you and inquire:
- can you find
something which is doing the hearing? An I, ears, a body..
- can you find
the sound going to the head where it is received and interpreted? Or is it rather, from the perspective of the body, just out there?
- can you find two things there, the number 2 (the process) and the number 3 (the heard)? Or can you only find one thing happening there in/as the experience we call hearing? I mean by that, do you find a thing called 'hearing', or can you just find the sound? Or perhaps we could turn it around, and say we don't find a sound, we only experience hearing? Or we could even label it as just 'sounding'.
- already asked this in a way, but am phrasing it a little differently here: can you find a listening/hearer/I that is separate from the sound?
- do you notice how images/thoughts are imposed onto the experience that label the sound?
- If I say that there actually aren't 3 things there. And not even two, not an observer and an observed, but that it would be more true to say that the observed and the observer, or the experienced and the experiencer, are all wrapped up as one.. does that resonate, does that seem aligned with your experience?
So in the initial statement 'I hear a sound', how would you rewrite that sentence just to make the sentence as aligned with your experience as possible with language?