Answer
Of course, "free will" can be used in various senses. If someone wants to use the phrase to refer to the obvious fact that we do what we desire to do (i.e. "compatibilism"), I can't imagine any serious objection. Here we are just using a word to describe a capacity that everyone agrees we have. Even libertarians agree that we have compatibilist freedom; they just want to insist that we also have freedom in another sense as well.
Of course, those who use "free will" to refer to compatibilist freedom must beware of misleading people. There is a tendency to equate "real freedom" with libertarianism. So one who claims "real freedom" and interprets the phrase in a compatibilist sense may lead his hearers astray.
And of course the very idea of a "will" which exists in some independence from the person, the intellect, and the emotions, is deeply problematic. See my Doctrine of the Knowledge of God for a more "perspectival" view of intellect, will, emotions, imagination, etc. So I prefer to speak of "freedom" in general rather than free will.
Agent causation is certainly an interesting concept. In common discourse, we often consider the decision of an agent to be a sufficient causal explanation. E. G., We find a newspaper on a chair and ask how it got there. When told that the wind blew it there, we obviously want further explanation: how did the window get left open, so that the wind could mess up the living room? But when we're given a personal explanation, "Joe put it there," we don't usually ask further explanation, except about Joe's motives. So personal explanations tend to satisfy causal questions in a way that impersonal explanations don't. That has implications for theistic arguments and the like.
Still, it is at least abstractly possible to ask what caused a person to decide in a certain way. Those further questions can be answered along the lines of psychology, and those along the lines of neurology, genetics, etc. So in some contexts it makes sense to regard agent causation as something needing explanation, rather than as itself a final explanation.
And the phrase "Joe decided" requires further explanation. If it means that Joe's will acted without cause, independently of his desires, then agent causation is the same as libertarianism. If, however, Joe's decision is determined by his desires, then we must ask where those desires came from. If they are undetermined, the same problem arises as with libertarianism. If they are determined, then we must ask where they came from. This discussion progresses through a causal chain all the way to the will of God. So our final choices seem to be still between determinism and indeterminism. And I would argue that any kind of indeterminism contains the same problems as libertarianism. With any kind of indeterminism there is something that pops out of nowhere, with no explanation, that invalidates moral responsibility.
Answer by Dr. John M. Frame
Dr. John M. Frame is Professor of Systematic Theology and Philosophy at Reformed Theological Seminary in Orlando, FL.