How does God know the future–or does he? Some Christians might consider the question presumptuous. That's a mystery!
However, Isa 46:10-11 indicates that God knows the future by willing the future.
Conversely, freewill theism posits a condition (man's libertarian freedom) that poses an impediment to divine foreknowledge. And philosophical theologians of all stripes concede the dilemma. Some freewill theists labor to reconcile divine foreknowledge with libertarian freedom. But that shows they are acutely aware of the tension.
1. To take an illustration, suppose we compare God to a cyberneticist. Suppose a cyberneticist creates 100 robots. Each one has different programming. The cyberneticist knows what each one will do if he activates it.
Likewise, he knows how they will interact with each other. Depending on which robots he activates, the results will be different.
The unactivated robots are like possible worlds. And the cyberneticist is the source of all these alternate scenarios.
That's analogous to Reformed theism.
i) This has significant upsides. It clearly grounds divine foreknowledge and counterfactual knowledge.
ii) It preserves the sovereignty of God, as the absolute Creator.
iii) A potential downside is the complaint that determinism implicates God in evil while robbing man of moral responsibility. Of course, that's an ancient, perennial debate. If we stick with the robotic metaphor, that raises to the question of whether androids are personal moral agents. That's a popular topic in science fiction literature, going back to Asimov's I, Robot. To insist that a robot can't be a person or moral agent simply begs the question.
2. Contrast that with freewill theism. The cyberneticist dies. Years later, an investigator discovers his secret laboratory.
In Molinism and Arminianism, the investigator knows, by consulting the notes of the cyberneticist, what the robots will do, individually or in combination, if activated.
However, he doesn't know it because he made them. He doesn't know it because he programmed the robots. He is not the source of what they will do, if activated. Rather, what they will do is the source of his foreknowledge or counterfactual knowledge.
i) A potential upside is that it seems to diminish the tension between divine agency and sin. However, it has many downsides:
ii) With respect to (i), there are roughly two aspects to the problem of evil: (a) How can God be blameless? (b) How can man be blameworthy? Even if this model explains how man can be blameworthy, it fails to exonerate God from complicity in evil. The outcome is still dependent on something God did. In that respect it's no improvement over the perceived problem of (1).
iii) It fails to explain how God can know the future. Indeed, it seems to remove a necessary condition for divine foreknowledge.
iv) In fact, it fails to explain how God can know all possibilities. He's not the source of these possibilities. On this view, what humans would do is a given. Autonomous possibilities. God must adapt to that framework.
v) If human choices are ultimately uncaused, then how are we responsible for them? In what respect are they our choices if they are ultimately uncaused? If, on the other hand, they are ultimately caused, then isn't that deterministic?
vi) It reduces God to a Demiurge. There's a realm of abstract possibilities independent of God. Equally ultimate. God simply chooses which ones to switch on.
3. In open theism, he doesn't even know for sure what they will do. Their programming is adaptive and stochastic. Once activated, it takes on a life of its own. The end-game is unpredictable from a distance.
i) One upside is that denial of divine foreknowledge is more consistent with man's libertarian freedom–assuming man has libertarian freedom.
ii) A downside is that it makes God a mad scientist who activates robots to find out what they will do.
A freewill theist might exclaim that by comparing God to a cyberneticist, I've just conceded that Calvinism reduces men to robots! But aside from the fact that that my illustration is metaphorical, I'm using variations on the same robotic metaphor for Calvinism and freewill theism alike.