Suppose you have two intelligent agents interacting, with each one one's behavior based on their prediction of what the other will do. For example, suppose you have two mind readers playing rock, paper, scissors. It is impossible to predict what the other will do. Alternatively, suppose someone attaches a machine to my brain that reads my mind and tells what I will be doing for the next 10 minutes. I can always improvise by making a deviation from the predicted behavior.
It would seem that there are limits to how well a person's behavior can be predicted. Can there truly be determinism without predictability? Without being able to set up experiments to successfully test the prediction of a person's behavior, doesn't determinism become scientifically meaningless?