Here are a few previous entries from Tom that may help.
Real influence may limit choices, but influence does not erase free will. Absolute influence kills free will by definition as does zero uncertainty (zero unknowns as you say), but absolute influence is like infinity and zero uncertainty — an abstraction that cannot live in a real, viable, actual, or useful world — i.e., a world that has the potential to evolve. Conclusions based on these abstractions don't apply to you, me, or a bumblebee. You may sometimes feel boxed in by influences, but you always have choices available to pick with your intent guided free will. Inevitable when considering the rules of AUM, free when considering fractal evolution.
Free will action follows intent — intent has many choices, and each choice is full of unknowns — intent is for most of us an expression of our state of incompleteness and ignorance. There are lots of random components (fluctuations) about any instantaneous animating intent — forming up an intent to guide an immediate requirement for action/choice is not a precise process. Our calculations are bracketed by lots of error bars and represent a statistical process much more than a precise or deterministic process
It appears that there are no choices when you do not consider the ability of the being to change itself, to grow, to decrease its entropy. Our intent changes and thus our array of possible choices change because we change — we grow up and become someone else as we change the quality, the entropy content of our consciousness. When you think of a static (non-growing) entity it appears that new choices are hard to come by — they are who and what they are. Yet, because there is free will there are always new choices, better choices, we just have to grow up enough to grab hold of them and grab hold of them so we can grow up. No chicken and egg problem here, they both happen (evolve) together. Epiphany! Satori! Our desire to grow, evolve, and improve ourselves interacting with our free will delivers many (some large, some tiny) “eureka“ or ahhh ha moments (some almost unnoticeable in their more typical micro form) which accumulate and enlarge our decision space (provide a larger set of choices). This is how we are able to pull ourselves up by our bootstraps — the magic of self-focused evolution trying something new on a chance of increased productivity (growing up, decreasing system entropy). Only dead stuff (no consciousness/no free will) doesn't have the capacity to grow (improve itself) and deliver up a whole new set of bigger and better choices.
Is not the act of choosing by a rational person following conventional reasoning simply picking one of the available possible choices within its decision space? The intellectual act of choosing when completed leads to a decision — a commitment to some action, a choice, or conclusion which is the result of the choosing. Does not the verb choosing pick a noun choice from the available possibilities? If a choice was not plucked from the available possible choices, then the actual choosing did not yet take place and is still in process. It appears to me that free will gives the intent of a rational person following conventional reasoning the freedom to choose from the available choices.
A rational person applying conventional reasoning always has choices even if they cannot list them (enumerate them with their intellect). A failure to be intellectually aware of their choices is a failure of intellect and awareness, not a failure of free will or a lack of choices. viewtopic.php?f=4&t=54&hilit=a+rational+person