Just what, if one is a Calvinist, can be meant by human free will? And how, given that everything that happens is decided in advance, makes a human beings responsible for their actions? These are the most common questions aimed at those who are committed to a strong doctrine of sovereignty, one that features the idea that God determines all that happens in advance.
Determinism is the idea that for everything that happens there are antecedent conditions such that, given those conditions, nothing else could occur. For a Calvinist, the antecedent condition in question is ultimately God's will. God's will is such that every event in creation is determined by God in advance of the event. We call this Divine Determinism (DD).
The debate over free will hinges on whether or not free will is compatible with any kind of determinism. One is either drawn to compatiblism or incompatiblism. This leads to two distinct views of what free will is. Libertarian Free Will (LFW), as most commonly conceived of, is the idea that to make a free choice one must obtain the ultimate ability to choose from alternative possibilities without a determining factor outside the human agent. Compatibilistic Free Will (CFW) holds that free will is compatible with determinism and that even if an action is determined one is free if one is able to follow through on one's desire/volition.
Probably the most important consequence to any view of free will is its connection to moral responsibility. If human beings are morally responsible for their actions there must be some condition that makes them morally responsible. For those who hold to LFW this is (most commonly) the idea that, in any given action that is freely undertaken, it is possible to do otherwise. This principle has a name--the principle of alternative possibilities (PAP)--and sounds reasonable enough, but it does need to be clearly stated. PAP is not merely about what is possible to imagine, but what is possible to actually achieve in a human action. It states that an action freely taken is one for which the agent is morally responsible only if the agent could have done otherwise. You can see that this thesis is somewhat difficult to hold if one is committed to determinism.
The strongest intuition for most people is PAP. For, the intuition says, how could I be responsible for an action I was predetermined, by an agent outside my control, to carry out? And if one follows such an intuition one is most commonly led to believe that the action was determined solely on one's freely choosing the action from a number of alternatives. If I decide to become an axe murderer, for example, I am responsible for such a choice because I could have chosen otherwise.
In order to critique such an intuition it is necessary to come up with some alternative possibilities for a condition that would render an agent (a human being) morally responsible for his or her action even if it was predetermined to occur. This, says the compatiblist, is perfectly possible. But it is also necessary, in order to win the argument, to provide reasons why PAP is false.
Let us begin with the latter. Out of all the arguments against PAP I am most persuaded by two. First is the argument from God's foreknowledge. The foreknowledge argument states: God knows all future events (including all human choices) in advance of those events taking place. In other words, God knew what I will choose to do today even if I don't. If God knows what I will do before I do it then it is not possible for me to do other than what God knows I will do. Therefore, I do not obtain the ability to do otherwise and PAP is false.
There are at least four responses to this and they all consider ways in which God could foresee a free choice, but not determine it. First, God might not know what I will do even if he might be able to predict the most likely outcome (this position is called 'open' theism). Second, God might not see events in advance since he is outside time and sees everything in the present. Third, God might simply see the future without controlling the future rather like viewing the future in a crystal ball. Finally, God might be able to see all possibilities and, consequently, be able to know what I would do in any given situation. The latter position is perhaps the fastest growing position and hotly debated in theological/philosophical circles.
If one finds one of these options attractive one may continue to hold to PAP and to LFW. I tend to think that none of them solve the essential problem raised by the foreknowledge argument. Open theism, I think, denies a basic Biblical doctrine of God's exhaustive, comprehensive knowledge (see here for my argument against open theism). Simple foreknowledge and presentism are unconvincing due to the fact that neither really responds to the problem. In both cases God remains knowledgeable about a given event and the actions of people - he knows what will happen or, in presentism, happens, and it is not clear to me how a person could do other than what God knows he or she will do or is doing. Molinism (see my pejorative and silly critique here), in my opinion, fails because it is not clear how God can be justified in his belief of what one would do in a given situation. And if this knowledge that God supposedly has is not justified then what kind of knowledge is it? (See here for more on Molinism and its critics).
The second argument against PAP comes from James Anderson (see here) and has to do with the incarnation of Christ and impeccability. God is necessarily good so God cannot sin (that's what impeccable means). Jesus Christ is God incarnate and so Jesus Christ cannot sin. Christ, in his earthly life, could not have done otherwise than not sin. Christ was morally responsible when he did not sin (this is what makes it possible for him to bear our sin). But if the ability to do otherwise (PAP) is necessary in order that Christ was morally responsible then Christ was not morally responsible for not sinning. So, PAP is false.
To get around this one would have to deny Christ's impeccability. And some theologians do. But the reason people seem to deny it is that they wish to cling to PAP. It is quite a high cost since one would have to suggest that Christ's moral perfection was not a sure thing and that it could have gone the other way. In other words Christ could have sinned and therefore been unable to represent sinful human beings on the cross and consequently there would be no salvation for anyone in history. This seems to be close to saying that God could have failed in some significant way.
In order to suggest that human beings are morally responsible for their actions while they are determined by God to occur one also has to provide an alternative to PAP. Compatibilists have at least two lines of thought. One is to point to human desire. To be free is to do or get what one wants. If I desire to be an axe murderer (I don't know where, from my subconscious, I dragged this example, but for some reason the movie So I Married and Axe Murderer comes to mind), then I am responsible for being an axe murderer even if it was predetermined to happen.
James appears to point to human volition as being what we are morally responsible for. It is, after all, human desire that presents itself as the beginning point of sin: "each one is tempted when he is carried away and enticed by his own lust. Then when lust has conceived, it gives birth to sin; and when sin is accomplished it brings forth death" (James 1:14-15). If desire (or lust) is what makes a choice to commit a sinful action free then it is also what makes a person morally responsible. And desire, as a condition for free will, is compatible with determinism.
To test this against the intuition of moral responsibility imagine that you are in heaven and God tells you that he determined everything. Do you still have the intuition of moral responsibility? I seem not to be able to shake it even if I had no possibility of doing otherwise. You may, perhaps, find yourself indignant and ready to protest, but is it really possible to eradicate the intuition of moral responsibility? Indignant does not imply that one is exonerated. I simply find it impossible to believe that there is much of anything that could remove the intuition that I am responsible for my actions. And since the argument for PAP rests on the intuition that a person is responsible for his or her actions it can be replied that the intuition is as strong even if one accepts determinism. (note the above argument is not supposed to prove the falsity of PAP. It only seeks to show that moral responsibility is a strong intuition that may even be possible if PAP is false. That also is only an intuition!)
The strongest objection to the idea that desire is what makes a person morally responsible is to suggest that there are some people for whom desire is not what makes them morally responsible. For example, a drug addict appears to have very little say as to whether or not to take the next hit. And if it is not motivated by desire then it is difficult to say what makes him morally responsible for his actions. This is quite difficult to respond to in plain determinism, but for DD there is a response open. It is to suggest that, for those who appear to be utterly unable to control their desires (they might desire to change their desire, but are unable) is to point to another condition for moral responsibility from a theological appeal to human knowledge.
This, less common, line of thought among compatibilists is to suggest that what human beings are responsible for is knowledge. This knowledge is common to all human beings and is clear. It begins with knowledge of God "clearly perceived" and God's disposition towards them "revealed" by God. Paul begins his letter to the Romans by asserting that human beings know God clearly but deny God (by "suppressing the truth in unrighteousness"). Paul says that it is this knowledge that makes human beings responsible and that all human beings are "without excuse." Paul also says that God's wrath (his extreme disfavor) is revealed to human beings. This is known to human beings through their consciences and, to those who hear it, through the gospel.
I find this quite persuasive because, when conjoined, desire and knowledge provide the necessary conditions for moral responsibility. I am morally responsible for my sin because I wanted to sin and because I know God's disfavor towards it and, consequently, I knew it was wrong. Any defense I might want to give related to whether it was possible to do otherwise seems insufficient in light of my wrong desire and knowledge of what is wrong.
I find myself committed to DD and to a compatibilistic view of free will. I think it is Biblically warranted and philosophically satisfying. It is also existentially relevant since I also think it produces better grounds for faith. I can trust that nothing occurs without the explicit decree of God having made it occur. My faith is sure not through my autonomous free choice (it is quite possible, given that kind of free will (LFW), that I would never have chosen Christ), but through God's electing choice of me. Why does he choose me? Well, it is not because of anything in me. Rather, God chooses to save some because of his Grace. Therein lies an eternal mystery, but one I am ever grateful for.