(BTW, I use the word "volition" a lot in writing about free will. "Volition" refers to our capacity to make choices.)
I find it curious how often libertarian views of free will are found in theological systems and debates. I'll have more to say about this in a later post. But recall the point I made in the last post, how modern concerns about free will focus upon causality and determinism. If our choices are the product of brain chemistry and the deeper laws of physics, then we are not free. Consequently, libertarian theories of free will attempt to extract or separate volition from determinism. It is believed that this is the only way to preserve genuine human agency and moral accountability.
The sticking point here concerns how you introduce indeterminacy into a causal chain. Religious people often point to the soul here, how the soul allows us to escape the causality of neuroanatomy. Non-religious theories of free will have pointed to things like quantum indeterminacy to escape the deterministic trap.
These ideas, however, are contentious. Pointing to the soul appears to be a classic "Deus ex machina" argument. And it's also unclear why quantum randomness preserves the integrity of human choice by turning our decision-making into the spin of a roulette wheel. Einstein famously said about quantum mechanics, "God doesn't play dice with the universe." The same could be said about quantum theories of human volition.
That is my basic criticism of libertarian theories of "free will" as typically described in these debates. Simply put, these theories replace determinism with randomness. Even in religious views of freedom. Appeals to the soul simply back up the problem. For example, how does the soul come to want what it wants? How does the soul come to make a decision? If there's some historical chain behind the soul's desires and priorities, some linkage of prior causes to effects leading to this current moment, the bogeyman of determinism returns. And if there is no backstory that leads to the soul's current desires and priorities, then those desires and priorities become arbitrary and unmoored from the stream of my life history. Either my choices have a story, or they do not. If my choices have a story, the bandwidth of my decisions will narrow, flowing coherently and predictably from my life history and current character. If my choices don't have a story, then my actions will appear inexplicable and unpredictable, to myself and others, disconnected from my past and character. I won't "recognize myself" in the decisions I make. Conversely, if the soul is hovering in an indeterminate state between two choices, we're back to throwing dice.
Overall, then, sure, you could point to the soul in an attempt to extract choice from the neuroanatomy, but you're going to struggle to describe a coherent theory of soul-based volition that doesn't raise similar problems to the ones you were trying to avoid. That's what I find missing in these debates. We gesture toward "free will," thinking free will will solve some theological problem, but we fail to articulate a soul-based model of volition that can plausibly fill that gap.
In contrast to libertarian views of free will, soulish or quantum, the other dominant view of the will found in theological systems and debates is Augustinian.
The Augustinian view of the will is summed up nicely in Augustine's famous line from the Confessions: "Our hearts are restless until they rest in Thee." In this view, our will only becomes free when it comes to rest in the will of God. But this is a different view of "freedom" than the one being offered in the libertarian view, a contrast that is hugely important in our debates about "free will." In the Augustinian view, the will becomes more "free" the more it becomes "captive" to the will of God. To conflate some psychological and theological ideas here, we "self-actualize" when we more deeply participate in the life of God. (The word "self" in "self-actualize" is problematic, but I hope you get the idea I'm gesturing toward. We become our fullest selves, we flourish, when we surrender to the will and love of God. When my will becomes God's will I reach a state of bliss, beatitude, and joy.)
Freedom, in the Augustinian view, isn't a capacity intrinsic to human volition. In fact, most of humanity is experiencing unfreedom. We are enslaved to passions, fickle in virtue, blinded in perception, and captured by pride. In this Augustinian view of the will, full "freedom" is something out ahead of us, less a capacity we possess than something we grow into and acquire. We become free.
And again, this freedom is a sort of constraint. We become free when we can only will only one thing purely--the will of God. This is why Augustine famously said, "Love, and do what you will." The vast freedom of "Do what you will" is constrained by our prior "enslavement" to love. Once the will is "enslaved to love" we are at liberty to do anything we want. We're free.
In summary, this contrast between libertarian and Augustinian views of the will plays a critical part in all sorts of theological debates, especially those concerning hell and universal reconciliation. More on that topic to come.