The concept of not being able to change the past is rooted in the idea that existing things cannot cease to exist. When discussing divine foreknowledge, we are acknowledging that existing things are not contingent but instead necessary. This means that they cannot fail to exist because they have already occurred. Since we are unable to alter past actions, it becomes clear that we do not have the freedom to make them contingent. As I write this, my actions are in the past, making the reality of what I do necessary. Otherwise, I would have the ability to change it. Additionally, my actions are interconnected in a series of events that are inherently necessary. If they were not necessary, they would not exist. If I were to claim that there were contingent aspects of my life while looking back, it would undermine the necessary connection between the past, present, and future, ultimately denying the existence of those past choices. As I write, the connection to my previous writing is necessary in order to continue the rest of the post, highlighting that all of my actions stem from a cause external to myself, known by God, who is the reason for my actions. Without this reason, my past actions would lack necessity and be subject to change, contradicting the notion of God's necessary and infallible foreknowledge, as I am unable to alter what has already occurred.