The concept of necessity is one that, on the one hand, seems really simple, and yet proves itself to be rather difficult to track. When talking about theology, we usually are referring to the concept of ontological necessity, or what must exist. Another way of thinking about it is that it is impossible for necessary things to not exist.
In Christianity, there exists only one necessary thing: God. Everything else is what we call contingent, that is reliant on something else. The belief that God is the only necessary thing is called aseity, that God exists a se, or "by Himself". Now the question that I want to ask here is how does this affect Arminianism and Calvinism?
Now I wrote a post a while ago called The Teological Argument For The Existance Of Libertarian Free Will, and the point I'll be making here will cover some common ground. But rather than simply arguing for the existance of LFW, I am instead seeking to explore the effect of compatibilism and necessity.
What In God Is Necessary?
So the first question is, what is it that makes something necessary? The answer is that something is necessary if it must exist. In other words, it is impossible for it not to exist. This would be true of God. This would also need to be true of any of God's essential attributes. After all, it would be nonsense to say that God exists necessarily, but He could be someone and something completely different than He is. Rather, we need to also affirm those aspects of God that make God God. For instance, God is necessarily omnipotent, omniscient, morally perfect, incorporeal, and eternal. He is necessarily tri-personal, which grounds His essential goodness. Without these properties, God would simply not be God.
But there are divine attributes that God need not have which He does. Those are any attributes that define God's relationship to something outside of Himself. For instance, God is not necessarily creator, for He could have chosen not to create. God is not necessarily the God of Israel, for Israel need not exist. God is not necessarily just, for God does not need to be in the company of sinners (though He is necessarily righteous/good).1 So even though God is necessary, it does not entail that everything we can say about God is also necessary.
What Will The Will Do?
This brings us to the most important question. Are God's choices necessary? Now the Arminian clearly says no. This is because the Arminian believes that God possesses LFW, and thus His choices are not necessary since that is basically what LFW means.
But what about compatibilism? This is a bit more difficult since I've heard half a dozen different definitions of compatibilism. One basic one is that compatibilism is the belief the free will and determinism are compatible, which isn't particularly helpful. One holding to this definition without any further development could simply say that God's choices are not necessary but couldn't have been anything else. Because they said so. This has always struck me as saying "I believe in A and not A".
However, most Calvinists that I have met generally argue that by compatilibilism they mean that one acts in accordance to one's nature. That is, you chose what you chose because it is in your nature to make that choice, and because it is YOUR nature, it rightly belongs to you. Thus your will is free. To be frank, this actually makes perfect sense to me. This is basically how I understand the operation of the wills of animals.2
So for God, these compatibilists will argue that the choices that God makes He makes because they are the natural result of His nature. So because God is perfect, and good, etc... He inevitably creates the universe. Therefore, if God did other than what He has done, He wouldn't truly be God!
However there are problems when applying this understanding to God. If God's decisions are the expression of God's nature, and God's nature is necessary, than logically all of God's choices are necessary. God could not have acted other than He has.
However, if all of God's choices are necessary, the effects or those choices are equally necessary. This would collapse the distinction I made in the above section. God would necessarily be Creator, so He would need to create. God would necessarily be the God of Israel, so He would need to commission Israel. God would necessarily just, so He would need to be in the company of sinners to judge them.
The fundamental result is that everything is necessary, and nothing is contingent. This makes God dependent on His creation, since He needs to create it. It is not dependent like I am dependent on my heart, but dependent like I am dependent on eating: I must do it or I cease to be. This strikes me as a challenge to divine aseity, and a diminishing of God's glory.
I find this to be ironic since most compatibilist think that they are bringing God glory through their theology. However, I believe it is quite the opposite. Compatibilism makes God smaller, mechanical, and dependent on His creatures. While the idea of making human actions necessary may sound appealing to the Calvinist, a flat our rejection of libertarian free will makes that extend to God as well, diminishing His glory and honor.
So to my Calvinist friends, I suggest that you embrace the notion of LFW for God, just as I embrace the notion of CFW for animals. Then we can quibble and argue over the free will of humans.
1 For more on this, see my post: http://jcfreak73.blogspot.com/2014/06/essential-attributes-verses-relational.html
2 Though, of course, animals are not moral agents.This is why I do not believe it would make sense with humans or angels who are moral agents.