This is good. I you asked a question that actually required me to go to a computer rather than use my pone to respond.
At a very basic level predestination can be rooted in divine omniscience. If God knows what will occur then everything is predestined to occur as God knows it will. If God, knowing what will occur, engages in the act of Creation then God has ordained everything to occur in that manner by the very act of creation.
If I know for certain that I will eat a ham sandwich if I go to the ham sandwich shop, then my eating of the ham sandwich was predetermined by my going to the ham sandwich shop.
So I believe that everything is predestined and even decreed, based on an omniscient Creator. This leads me to most of the conclusions that is held by Calvinists. God unconditionally chose who would be saved and who would be damned based on (at a minimum) omniscience and decreed by the act of creating. Christ died to save those who would be saved and to (ultimately) condemn those who would not be saved. What God has known would happen will happen. That would at least get me to four-point Calvinism. I believe that there is nothing in us, apart form the work of the Spirit, that will lead us to salvation.
But I arrive at those conclusions without the judicial philosophy of Calvinism. I still use, of course, philosophy. But it is different and I do not pretend it is written in the text of Scripture. I simply believe that Creator God is omniscient. The rest falls into place (except for depravity, which is derived from Scripture).