Quick note: This is turning into one of the best free will discussions I've had.
I would call the idea that we can choose reason or choose to not use reason nonsensical, because while they are asserting free choice LFW is missing the key component to explain the will itself.
But, that's just it. They cannot explain the will. By it's very nature it must be unexplainable. If it were explainable then it would work by deterministic forces. That's what explainable means. It isn't explainable. It is magic. It is completely other than the material world. Spirit. The problem they have if they want to maintain a material world is the means by which the spiritual (or mind, or whatever you want to call it) and the material interact. But even there, my materialistic language starts to cause problems because I am again looking for a mechanism -- which, you guessed it, implies materiality.
This makes the conception extremely difficult to reconcile with our current view of the universe. It does not make it logically impossible.
Okay, let's say I am confronted with a situation where I could apply reason or I could choose to not apply it. How do I decide which I want to do? Seemingly, if I want to apply reason, then I will. If I do not want to apply reason, I will not. Do I decide which I want? If I do decide which I want, how can I decide it based on anything other than what I want?
How would a libertarian answer this: Can I want to want something that I do not want? It quickly forms an obvious infinite regress. Instead of viewing what we desire, our drives or motivations as REVEALING themselves to our consciousness, they create a false decision to want. However, as I am trying to illustrate, this notion of will is totally nonsensical. The will cannot decide to be. It is there or it is not.
No, they would say that their faerie sees the possibilities -- those provided by reason, those provided by desire and which may contradict one another -- and the faerie decides amongst the choices. Your brain does something similar under deteministic forces -- it arrives at a decision by weighing different possible courses of action (OK, it's easier to use dualistic language and this really bears no realitionship to what actually occurs in the brain) and that decision presents itself to consciousness. Consciousness is just what we use to reconcile decision (which is almost if not always unconscious) with the outside world -- that is one of the reasons why I think the mirror neuron system is intimately tied to this process we call consciousness.
an unappealing variety of 'freedom' at very least.
Personally, I think it's worse. I don't think it's freedom at all. It may be un-determined, but I don't see how the conjuction of indeterminacy and determinism creates libertarian free will. In essence, I think he is fooling himself. I still like him as a person and teacher very much, but he very clearly (to me) wants to hold onto his theistic views and is willing to fool himself into believing in free will as the only way to make sense of the problem of evil.
However, this does raise a free will problem: If our minds are the only grounds in which causality is real, does it make sense to say our minds are free from causality?
Well, I don't think so, but I am open to the proposition that I am wrong. I also don't think it is safe to say that our minds are the only grounds in which causality is real. What Kant seemed to produce, at least for me, is the idea that we bring causality to the table. We see causality. That does not mean that there is no causality out there, but we have no possibility but to see it. The quantum world creates problems for us, but we still see causality at the level that we operate, I believe, because we are evolutionarily adapted to think in that way -- because that form of thinking works in the universe we inhabit. It means that we must be careful in our thinking and our language. (And, yes, for those of you playing at home, I am well aware that evolution as an idea depends on a causal-deterministic framework, so I am making an assumption of causality in the preceding statements.)
As to whether or not it means our minds are free from causality, that doesn't matter as far as REALITY is concerned. It is clear that we can only see what our sensory systems allow us to see (using one sensory system for the metaphor). But with the aid of science, we know that there is much more to the electromagnetic spectrum and much more to the olfactory world, for instance, than we can ever experience directly ourselves. It could be that there is an entire world of magic/spirit out there that we cannot experience because we don't have the receptors for it. I still see no way for material and non-material to interact -- in any way -- since any such interaction would necessarily be material for it to have a mechanism. But I am also open to the very real possibility that our thinking ability is puny compared to what the universe may contain/be. This does not mean that we should begin to believe in woo, but that there may be more in heaven and earth than are dreamt of in all our philosophies.
Regardless, we are stuck in who and what we are. We have no option but to believe what we can make sense of and to forgo all the woo possibilities. Knowing our limitations, however, forces me to be a fallabilist. I don't pretend to know the nature of REALITY.