The key point for the case of Open Theism is the claim that you cannot influence and foreknow without being in control to the degree that you foreknow, because if you know what will happen as a result of your influence then you are responsible for what happens. You can only foreknow and not control if you do not influence. So if you do not believe in an observer God that does not influence, and if you do not believe in a God that controls us absolutely, then you must conclude that God does not foreknow what we will do absolutely.
I ask you to imagine someone who knows the future in every detail. Does he see only one future or many futures depending on what he chooses to do?
If he sees only one future then either what he knows has no impact on what he chooses or what he chooses has no impact on the future. If he sees many futures depending on what he chooses to do then by his choice of what to do, he choose which future shall be.
So lets list the three possibilities:
1. He sees many futures depending on what he chooses to do and by his choice he chooses which future shall be.
2. He sees only 1 future and what he chooses to do has no impact on the future.
3. He sees only 1 future and what he sees has no impact on what he chooses to do.
1. This person decides the course of the future. Only his decisions matter and the responsibility for everything that happens is his alone. If this person is God, then being all powerful, the impact of his decisions have no limit and so He is in absolute control of every detail of the future. Whether He chooses to act or not to act in any particular situation, His choice is still the only one that matters in that situation and He is responsible. In this case, human beings have no freewill.
2. This person is effectively uninvolved in the world and has no great impact on the events of the world. If this person is God then He can only have no impact on the events of the world because He chooses not to.
This is the observer God of the Deists. If God is only partly observer and takes some part in the events of the world then He would have an impact on the future and that would have to be included in option 1 or 3.
3. This person is the strangest of all. It is as if he has no control over his own actions or he does not care about what he sees. If this person is God, however, then as the creator of the universe, He is most like the author of a book who has written Himself into His story. So as He reads the book afterwards He knows everything that is going to happen but that knowledge has no impact on His actions in the story because they have already been written. This option is essentially no different than the first option for God remains reponsible for every detail of what happens and mankind has no freewill.
Is it possible for God to have only limited impact on the world being only partially observer and partially involved? Since God is all powerful then the degree of God's impact on the world can be only be a matter of His choice, right? But if God has absolute foreknowledge, His choice of how He involves Himself and to what degree still absolutely determines the future (whether written before hand or not). Like the author of a book He can say who is responsible and have them punished for their deeds. But the reality is that the character has simply been written that way and has no free will at all.
