The Self is defined to us in contradistinction to the Other by encountering Feeling. I am initially the extent of my Feeling and the extent of Me grows as I exercise Will to arrange my life according to my valuation of those Feelings.
That said (whether of not it finds agreement in you), it would be impossible for another sentient agent to obtain certainty of those valuations and thereby "know" which decision my Self will make necessarily. Why is this impossible? Valuation of Feeling is made in the Self from the vantage point that only that Self occupies. Another agent (by some magic) might be able to link up with my Feeling in some objective accuracy and even know every aspect of vantage that my Self brings to that Feeling. But here is the rub. The other agent cannot "only" see my Feelings from my vantage, their own vantage is inexorably tied to it. I value my Feeling without the addition of the Other agent's vantage. The Other agent could only hope to gain the true vantage I have by completely relinquishing their own additional vantage. If they did this, they would have become me for I am the agent that Feels and values from this vantage and this vantage alone. Such is the Self.
But freedom from outside knowledge of my valuation's necessity does not free the Self from the accusation of valuing and deciding in some mechanistic necessity. How is the Self free? It could be that merely its autonomy can be called free. No one else but the Self was involved in the procedure. This seems insufficient as my valuations might be necessary, given my vantage and memories of earlier vantages. Stated thus , "Anyone who stood on this spot with this history and felt thus will necessarily value said feeling as X and decide predictably." We would be the sum of some mathematical complexity running down through history from the Creation. Is there an aspect of Feeling and or Valuation that may step aside from the mathematical sum? If there is an answer it need not be for all decisions (as we know that many of our decisions are made according to the autopilot) but only needs be shown possible for one decision.
I will suggest incoherence. There may be a True portent in a given Feeling (be it Pain or Pleasure) which the feeling agent may not be privy to. It will be his valuation that grants that Feeling the working intensity on which his decision stands. It will be felt subjectively. The key word is "felt". A Feeling is an assault on a sense receptor which does not have the capability of rigid accuracy but comes in with a possible range of sense benefit or insult. It merely claims good or bad broadly and awaits the Self's valuation to have any decisional merit. But it is "Felt" and for good or ill. It does not claim to communicate how good or ill and that valuation is up to the sensation (inaccurate but actual) and our opinion of how that makes us feel. For the good of Self and the task of Self (ordering such Feelings with the fluxuating range of sensation and the similar fluxuating range of accessible data from our vantage) our exercise of decision is the first anchored point in the process. If God or another has not decided to anchor all our actions and the Life provide to us was incapable of communicating an anchor of necessity because of its vagaries, it is left then to us. Our will makes the unnecessaries of Feeling and Vantage into a necessary and we, for Peace, continue through Life, not bound by necessity but trying to bind necessity to it.