I have always regarded free will as axiomatically real - in the sense that if you doubt free will then you doubt everything - but always had a problem in saying what it was, how it worked, how (in a world of cause and effects) anything could be free.
When I became a Christian, at first this did not change. I was pleased to find that Thomas Aquinas firmly asserted the reality of free will, but was disappointed to discover that he did not elucidate it but simply regarded it as a gift from God.
I was happy with this until I began to discuss the matter with 'WmJas' on his blog 'Bugs to Fearen Babes Withal'. The thing about WmJas is that if he does not understand something, he does not pretend to understand it - and he could not understand my attempted Aquinas summary (probably because there isn't really anything to 'understand' - it is simply a set of doctrines set down next to each other).
WmJas shook my faith in the adequacy of the Aquinas approach. I began to think: it is all very well to say we have free will and why - but what is it that we have?
The problem is that we generally talk and think as if everything has a cause, and every cause has a cause, and this leads to an infinite regress - so there is no space for free will to enter in to the causal chain.
My approach was then to ask where or what there is that that certainly does have free will?
The answer for secular materialists is - nothing. Free will is excluded by the assumptions.
But for Christians? God has free will for sure.
God has free will because God is an uncaused cause.
In fact, that is one of the divine attributes - albeit not expressed in this kind of philosophical language; but people understand that God wants and chooses without being 'influenced' by anyone or anything - he is the primary origin of motivations and actions.
I found this helpful, indeed it made a big difference to know that free will entails the property of being an uncaused cause.
But then, if God has free will, do humans have free will?
We already know that answer to that; and the answer is yes, humans do have free will - because divine revelation (e.g. the Bible) tells us that humans must be able to choose, in and of and from themselves, because humans are again and again choosing God, or choosing to reject God.
In fact, Christianity does not make any sense as Christianity unless humans have real free will. The ability really to choose is absolutely at the core of it.
So, since humans have free will - does that mean that everything alive also has free will?
No, only humans, and maybe a few other entities - but the point is that free will is not a universal property.
(Indeed it strikes me that a universe of universal free will would be a universe without causality - chaotic.)
But how could it be that only God and humans have free will? That is a very important question - and the answer is not one likely to be universally agreed on. But the obvious inference seems to be that God and Man share free will because God and Man share 'divinity' - and free will is a divine attribute.
This is NOT to say God and Man are the same, that would be absurd and is false - but that, at least to this important extent, God and Man are of the same kind: they are both the kind of thing which have free will, are autonomous agents, sharing the capacity to originate action: both God and Man are uncaused causes.
My conclusion - Humans have free will for sure, and this is an essential component of Christianity, and the only other sure example of free will is God - thus free will is a divine attribute - something we share with God.
And this implies that humans, even as they are in mortal earthly life and in sin, are divine beings - since only divine beings are autonomous agents.
(For Aquinas, the need for an uncaused cause, and unmoved mover, is one of the strongest arguments for a god.)
Does this analysis make a difference? To me it certainly does. I now feel I know what kind of thing free will is, what essential properties it has and what it means.
This description also clarifies why secular materialism (mainstream modern culture) cannot talk sense about free will - because they deny the divine and without the divine there can be no uncaused causes and no space for free will - merely an infinite regress of causation.
It also clarifies that any Christians who deny free will, and the autonomy of human agency, are (to that extent) wrong - and it is also wrong to overemphasize the earthly and sinful nature of Man when the reality is that we are mixed beings who contain this divine attribute of free will - and (since this is a divine attribute, not a mortal contingency) this is true no matter how depraved we are.
In other words, getting a clearer understanding of free will has led to a clearer understanding of much else - it has turned out to be a very important 'breakthrough' indeed!
(Thanks to the stubborn refusal of WmJas to acknowledge that my previous mode of understanding was adequate. The Socratic method, perhaps?)