These concepts, like many other concepts, may exist on a spectrum and not black and white. Consider an example where you are able to determine what to eat for breakfast this morning or not eat at all and do something else. There are choices presented to you from the environment that affect your decision making and you also have your own internal goal and other internal mental process that affect the choice. These 2 different internal and external factors will work together in your mind to determine the choices you make for breakfast this morning.
However, there are process where you don’t have much choice. For example, you can’t decide if your heart stop beating or not even if it’s entirely inside you. However, I’ll later argue that the mental working space is where potential free will happen and your heart is just another peripheral device that help keep the mental process sustainable. Blood and nutrition for the brain of course. But there’s a specific small space where free will happen, not in entire brain.
And there are mental process that have very high agency and as a result, a lot of free will, like you just wake up and decide to pray as a habit from internal goals this morning. High agency actions have more free will than other actions such as you going to the toilet (not having much choice isn’t it). You wake up in your same room, no outside stimulus, just an internal desire to connect with your faith, very high agency and mostly free will action.
Our brain has multiple parts. The brainstem I would argue doesn’t have much free will. It only take information from the body that you don’t consciously micromanage and keep it alive like breath cycle, heart beat, sleep wake cycle. It doesn’t have the complex internal goals and mental process. Its goal seems to be chemically regulated, a pretty simple system.
There are part of brain that have more free will. When you walk down the street, your eyes feed signals to the visual cortex to detect shapes and motion, while the temporal lobe recognizes objects like cars or people. The hippocampus provides your internal map. The prefrontal cortex decides when to cross or turn. However, the prefrontal cortex pull together sensory input from the visual and parietal lobes, spatial memory from the hippocampus then integrate it into a plan. There’s an internal saved knowledge about street sign, hazard, cars, and there’s an internal goal of crossing the street. That will then be mixed with external stimuli like images of cars and objects from your eyes. There’s a workspace where these 2 stream of internal and external information meet, that is where most of consciousness or free will decision making arise.
You have more free will when the external stimuli doesn’t affect your internal decision making in anyway and you have less free will when the external stimuli mostly or totally affect your decision making. For example, I once watch some people burn themselves in a protest, the heat doesn’t make them run and they keep standing or seating there. No matter if you agree with them or not, that’s an extremely high agency action and mostly free will. Even the lizard brain process of fight or flight doesn’t make them run for safety.
Now for the part where I’m projecting strongly. It may be totally wrong.
1) The internal mental process in our brain is just a physical process, just like the external information coming to our brain.
2) However, the amazing thing is some part of this internal process is so complex and multi-layered that it doesn’t get affected by the external process. For example, an animal will eat what they see, the only filter is either they are hungry or not. Some animal is so dumb in such a way they keep eating until they die from bloating. Sorry my gold fish. But we as human, when I look at food, I think of 8 different things or layers before I eat. For example, 1) am I really hungry or not, 2) does it look spoiled, is it a healthy food to eat, 3) do I have some work to do, if I eat now my job will delay, 4) did my wife eat yet, is this her food 5) did I say I would cut sugar and fat because I want to live longer 6) there’s a study where they starve mouse and it live longer 7) is this a right time to eat, maybe I’ll just wait for my wife maybe we go eat out later , so so many thoughts come to mind. There are religious people who do fasting on top of that as well. For animal, a mere image of food, which is a simple physical process itself, is enough to punch through and unlock all of their brain internal mental process to force an action and change their behavior that is to eat. For a human, especially someone with thoughts and higher agency, it’s much harder.
3) The more complex the internal mental process, the more it doesn’t get affected by the external physical world and it somehow affects physical world by itself. It’s like the other way around, the world doesn’t affect you but you can change the world, only when you have a more complex and multi-layered thought that doesn’t weakened overtime from external stimuli. For example, I dare you change the mind of Elon Musk to not occupy Mars, I bet he had 1000 complex reasons and you can not use 3 simple reasons to reasons with him. Your simple external information and reasoning is not enough to change the extremely complex internal brain process of Elon. It’s just not enough to unlock. You can’t unlock an extremely complicated lock with 10 layer of security with a simple key that can unlock 2 of the layer. However, Elon can change the world because his mind is now extremely complex “my mind is a storm, most people don’t want to be me”, that he somehow, from the sheer complexity of his internal mental process, that dictates his action and he went on to change the world.
4) that’s exactly how the brain can determine by itself and pick and choose what to do in the physical world where things seem to be deterministic from physical law. That comes entirely from its internal goal and information.
5) the brain is also controlled by physical law and contained within the world. But if it’s complex enough it will have its own small section of the physical world that can decide what it wants to do internally and projecting its action externally using our body.
6) I’d go so far to say while the brain is complex and can determine what it wants to do. Those entire process is actually just a physical process and if we understand it completely, we will know exactly what the brain wants to do next. New technology slowly show us this seems to be the case where we can predict brainwaves.
7) Even when we can determine and change the world based on our free will, that free will itself seems to be a deterministic physical process that happen in our brain. There is a confusing part here. How can i even say that free will is actually a deterministic physical process. Free will by definition is. Free will is generally understood as the capacity or ability of people to (a) choose between different possible courses of action,[1] (yes you can choose among the choices your free will or your brain give you, even when you try to think of other choices, your brain is giving you choices, it’s not like you can exist outside of your brain), (b) exercise control over their actions in a way that is necessary for moral responsibility, (yes, you can do whatever you see fit among the choices given to you by your brain) or (c) be the ultimate source or originator of their actions (yes, if your thought and brain is complex enough, it will not be affected much by external stimuli and the choice is almost totally yours).
8) So I think free will is fact that the brain is free by itself to choose given that it’s complex enough based on its own goal and internal process. However, the internal process of the brain appears to be another physical process, just isolate from the world because of its own complexity but it must abide by the rule of physics. You can not think faster than the speed of light, you can’t exist outside of your brain. The complexity of the brain, no matter how much, is built upon foundational physical law. No new law is created or no old law is lost. There’s no evidence that say the brain can transcend or whatever that word means any physical law. The only way you can prove that is to show the brain internal process violate some law, which is not possible yet.
9) In conclusion, yes you have your own free will to choose but the choices are bounded by physical laws.