Necessity and volition are not as opposed to each other as Arminians like to think. In fact, if Scripture is any authority on the matter, these two things are not opposed or exclusive of each other at all.
Here is a case in point; in fact this is the best possible case ever: Jesus was necessarily holy. It was absolutely and intrinsically inevitable that He be holy in every aspect of His life and perfectly righteous in all His actions. Secondly, it was absolutely necessary that He should die for the sins of the elect. Christ was so necessarily good that is was impossible for Him to be otherwise, notwithstanding, He was voluntarily good. That is why He could say, “My meat is to do the will of him that sent me, and to finish his work (John 4:34). Secondly, He could not avoid being put to death as an offering for the sins of the elect. Nevertheless, He died voluntarily. He said, “how am I straitened till it be accomplished! (Luke 12:50). And also, “I lay down my life, that I might take it again. No man taketh it from me, but I lay it down of myself. I have power to lay it down, and I have power to take it again” (John 10:17-18).
If this is not enough proof that necessity and volition are not mutually exclusive, nothing is. You may ask how this can be. Our only answer can be that it holds by the wise ordaining of God, who is great in counsel (Jer. 32:19). A true Christian will be satisfied with this answer.
It is safe to assume that very few Arminians, if any, would ever assert that is was possible for Christ to have fallen from grace by sin and to have perished eternally. But, as shocking as that notion is, it is an absolutely necessary consequence of the Arminian doctrine of contingency, whether any Arminian admits, acknowledges or avows it or not.