What is meant by the term: "free will?"
I think a lot of discussions on this topic hinge on this definition, and people often misunderstand each other here.
By free will, so we mean: "the ability to choose otherwise" or "the ability to not have our actions determined by that which is outside of us?"
Or is our understanding of free will "compatibalist?" That is, do we think "freedom" and "choice" are possible within the context of determinism (be it physical determinism based on the way God made the universe to work, or determinism in terms of God's divine foreknowledge of our actions)?
All people believe in choice and freedom in some sense it seems. Even if we believe in predestination, we also can allow that, in important ways, the people of North Korea are "less free," than the peoples of France or the United States. Further, we all experience a sense of volition, a sense of choosing, for some, but not all of our acts. So, we can agree on the difference between picking a menu item when we go out to eat, and blinking, breathing, or having our heart beat, which all occur autonomously most of the time.
That said, my position is that freedom is at the center of Christianity. What Saint Paul talks about in Romans 7 is a lack of freedom that occurs when our actions are driven by desire, instinct, and circumstance. Paul notes that in his inner self, he delights in God's law, but he is unable to carry out these actions. He is not a unified person, but rather "at war with the members of his body."
Paul is "dead in sin." Clearly, this is not a biological death. It is a death of personhood, and inability to seek what one truly sees as good. Obviously, there is still the experience of "choice," in this death. A sinner still knows the difference between chosing to try to seduce their neighbors' wife and blinking or a muscle spasm, the former as a volition aspect. The lack of choice comes from a lack of ability to order the desires, to make the will a "slave to righteousness," as we might like.
I am of the opinion the libertarian free will reveals itself to be contradictory. We cannot be "absolutely" free. Choice itself implies "choosing between." If I pick A and C, I am not free to have chosen B and D, nor all four options, nor to have refrained from chosing. Any definite action constrains freedom. Absolute freedom requires that we make no choices, since all choices are a limit on our freedom. But if we can make no choices while being absolutely free, it seems that absolute freedom collapses into a contradiction.
When we choose something, we either choose it for some reason, or we choose it for no reason at all (it is random action). If it is random action, then it is arbitrary, not free. If we have a reason for chosing something, then those reasons determine our actions.
Our reasons for choosing different things have to do with our beliefs and opinions, our knowledge and judgement. It seems to me like the development of all of these is uniquely tied up with states of affairs in the world, and thus our choices are tied up with (determined by) states of affairs as well. We might choose to love who we love and despise who we despise, but we do so because of who those people are. Thus, those choices are "determined by," who those people have revealed themselves to be.
So, my take would be that freedom is best understood as "self-determination." We are free to the extent that we, as a unified individual (not one divided against himself), determine our actions. And we are free to the extent that we are authentic to our true nature, the nature God created for us. As Saint Augustine says: "You have made us for yourself O Lord & our heart is restless until it rests in you."
We are truly free when perfected and fulfilling our true purpose, the contemplation of God. We will choose this if we are given the grace to be able to do so.
But all freedom is through grace. We do not create ourselves. We are effects of other causes. Thus, man's freedom is always a gift, working with God. We cannot be free apart from God, just as we cannot "create ourselves."
With that in mind, it seems to me like we have varying degrees of freedom. A fallen sinner can be free in how they choose to sin. We can recognize our need for God; as Romans 1:20 says, the signs of the Creator are everywhere. But even if this is brought to our attention, it is still a grace, for we only exist by grace.
And here is where I sometimes find myself disagreeing with Reformed Theologians I've read. Sometimes, they seem to be saying that we cannot possibly learn about God through mundane means, through meeting a pious Christian, through studying the wonders of physics, etc. Instead, they seem to be saying that any turn towards God requires a sort of magical intervention, as opposed to a natural one. But it seems to me like the One who creates and sustains, and who is within all nature can use nature as way shower us in grace. Christ is the Logos through which all things were made, the Word that speaks being into existence. Thus, all things are a sign of Christ (Saint Bonaventure, "an effect is a sign of its cause.")
So, IMO, a man can come to strive after God in many ways, but the point is that this always involves grace. It couldn't be otherwise unless it was us who created ourselves and our world. And so our freedom to pursue God is always conditional on Grace. Nature itself is a gift of grace, freely shared to all God's creatures.
We can be "free" in some senses, but we are only truly free, free to be our authentic selves, to the extent that we are "in Christ," the extent to which "Christ lives in us." For only God has no limits and is fully self-determining. Only God is fully transcendent, a true infinite. So it is only through God, the way in which we are "in Christ," in the same way that Christ is "in the Father" (John 17), through the Spirit, that we achieve true freedom. Human freedom vis-á-vis nature is only the simulacra of freedom by comparison.