A quibble here. This would make more sense to me if you said: "Volition, by definition, cannot be caused determined." I assume we agree that there is a cause for everything.
If you described cause the way I describe cause, we would probably agree, but I suspect you describe cause in the usual way, and in that way I do not agree everything has a cause.
This is hardly a quibble, as you put it. The entire philosophical world considers the question paramount (though it offers no solution except the kind Hume offers, which is to deny cause itself.) If cause in the usual sense is true, then, just as you say, everything has a cause, that is, every event is caused by some preceding event and every event causes some succeeding events, so that any event at any time must be what it is because of whatever caused it. The universe then is determined by those natural laws that determine what all events are.
This is not what I say, but this is the commonly held view of what cause and effect are. Obviously, one holding this view is hard pressed to explain how volition, or even reason are possible. The usual explicit (or implicit) method of escaping the problem is either to deny that everything is causal, to assume something else is injected into the stream of causation (like the will of God), or that ignorance somehow provides an escape from it, (if you don't know what is going to happen it is not caused). This last seems absurd, but is essentially the one used by all those who suppose quantum uncertainty provides an escape from determinism. Ask Alamo-Girl or betty boop.
(Note to Alamo-Girl and betty boop: I only pinged you because I took your names in vain on this thread and don't believe in talking about people without their knowing it. You need not respond. Of course you are welcome to.)
Hank