If something is "free" it is not controlled.
A will is something controlled.
A will to perform an action is a controlled will once that action is taken.
We all agree that not all actions are possible even if we are bound and determined to carry out our will.
What those limits, obstacles, impediments and unforeseen barriers consist of are IMPORTANT to our discussion.
Why?
They only have to be unknown, unforeseen and/or unknowable to make the supposed "freedom" of our will irrelevent.
At some point the impossibility of our will (to be carried out) enters the equation, does it not?
At least the "freedom to will" certainly does (when hampered by an unknown obstacle.)
If you can grant that unknown impediments to our will are not only possible, but, likely---you have taken the first essential step in eroding
the "free" part of free will.
What about the rest?
Subconscious motives were suggested by Freud. But, even deeper than that, we might suggest vestigial "instinctive" motives may be at work.
Why is one man attracted by redheads whereas another man might not be?
Why does one buyer prefer a Prius to a Hummer?
You can certainly follow chains of suggested "causes" for your reasoning. But, just past that event horizon of "known" motives, causes, determining factors lies the unknown.
It is in the unknown (to us personally--not unknowable) region where much of our so-called CHOICE is at work.
If you've ever played a lightning round of word-association you know there are obvious answers and also surprisingly weird answers.
Those "associations" go deeper than conscious thought!
Let us consider the genetic "information" contained in the mind of the GENIUS.
There are math geniuses who come from ridiculous isolated surroundings who may be idiots otherwise--yet--can perform astounding calculations faster than a hand calbulator. Ask yourself what "choice" is involved in this ability!
The range of human genetic influence cannot be limited to the occasional genius or serial-killer as a statistical flux.
I'm asserting that WHY we do what we do when we do it---is NOT actually known by us at all. We put a fiction on it and assure ourselves WE are doing it for cause and for reason and by CHOICE.
The IQ curve, the ideal, bell-shaped form approached by the graph of scores on the horizontal and numbers of scores on the vertical. Average, or 100, is at the maximum. Alfred Binet applied the term "genius" to a small area to the far right.