Free will is an illusion of the mind that is caused by a high level of conciousness. Humans that have a high capacity for rational thinking and decision making often mistake it for full independance. Let's start off by defining free will, free means liberty, and will means goals and intentions. An individual might believe what they want is fully decided by them, but the actual state of being them and all the events that led up are out of their control. For example, someone can think they're free to choose what flavor ice cream they like and it happens to be the sweet soft taste and smell of vanilla, if that's their palate preference, they simply cannot stop liking it and like something else like dark chocolate. When it comes to simpler living beings, they are characterized by either instinctual habits or the laws of the universe, and the higher you climb in the conciousness hierarchy, the more freedom of choice starts to "appear", but it is foolish to say that we have an immaterial superpower when in reality we just have had a way more successful and longer evolution process and were at one point a simple chemical bonding, one where nobody would even dare to argue has free will.

Look, just to clear things up, the first part of your argument is completely scientifically backwards. Studies consistently show the brain activity associated with decision making happens before, not after the individual makes the concious decision. It is true that individuals who believe in their liberty will transition positively to their everyday life, but that's not a contradiction of the lack of free will, it is evidence. If free will really existed, then the individual's wills wouldn't even depend on self belief, it would simply be free of anything, which means decided by nothing, now that is a REAL contradiction. You've admitted that determinism is scientifically most sound, but you're putting a feeling against a wrestling match with science, logic, and philosophy. We absolutely can understand how free will "feels" like it exists, that is perhaps what led us to have this conversation, get what I just did there?

That's a really nice piece of rhetoric, but let's examine the truth value for a second. The past is not a fixed and static timeline, we add to it progressively. That's why in the process of evolution and natural selection for example, change is ongoing, not because it's an independant concious decision being made by nature, but because what we call the future is eventually going to be the past, that's how progress is possible and ongoing. The past decides the future, and the future is eventually going to be the past and re-decide the future in efforts to make it more preferable. Even if you account for quantum randomness, by definition, randomness ≠ liberty, if that were the case then a non-rigged casino would make everyone a successful gambler. Either way, free will can't exist.

The difference in two brains when making a small decision or a large one is definitely a thing, but you're misinterpreting a difference in the intensity and volume of a mechanism for an actual change in the fundamentals of a mechanism itself. A computer doesn't fundamentally work differently when running a really large app versus a small one, it just uses more power and resources. You are right to speculate that science itself isn't a complete song, but you can't arbitrarily fill in its gaps. It would be unfair to uphold the rigorous evidence that science requires to determine something as true against a misstep in the human intuition while simultaneously undermining all the other side's evidences. There are tons of ridiculous ancient stories on how people gave mythological and supernatural explanations for what modern science has a much less interesting, sensible, perhaps simpler, explanation. The free will side rests easy on how it can't be disproven and ironically doesn't account for most forms as evidence while science actively needs to prove it as highly plausible under overwhelming empiricism, logic, and epistemological standards. You're right that in a society where wrongdoers aren't held accountable due to their lack of control, it would be a disaster, but I'm looking from a prespective of truth, not from a prespective of what's pro-social. If you really want the philosophical explanation that some might not be able to hold, wrongdoers should be punished not cause of the agony we have against them as their lack of free will makes scapegoats and revenges a fool's game, but simply to prevent them from doing wrong again.

Do you really want to know how we explain moments of genuine surprise? It's because in the past those events weren't common, that is the unironic reason. When you solve a problem in the shower that you weren't thinking about, your subconcious mind was still active, searching for reasons, searching for a connection. The lack of concious presence in the moment is actually evident against free will, not for it, you are unawarely being counteractive to your position. If the subjective presence of "I" wasn't there in the moment to come to a realization before my brain did, it showed that the brain is a complex pattern recognition machine that you are being reductive about. It actually points to the study we first talked about on how the brain is quicker than the concious experience. There is no such thing as "the space between randomness and determinism where real choice lives". That is a vague abstraction that begs the question.

I'm not making a leap of faith that science will eventually lead me to my conclusion, I'm just saying it's extremely unlikely that the road that goes the complete opposite direction of free will from what we have observed so far is what leads us there. Your "power" over the computer to turn it off is actually a consequence of deterministic hierarchy, not freedom of choice. You could turn the computer off to save money on electricity, out of habit, or perhaps just to make a point, all of which are movers of a decision you believed was fully independant. It's more accurate to see you were the tool to turn the computer off, not the decider to do so. Hear me out for a second, let's say you went outside for a drive. Your peers would describe you as a perfect textbook driver, you follow all the safety rules and do everything in your power. You could still unfortunately lose your life to a driver who drinks to cope with the loss of his wife and makes reckless moves as a consequence. He turned you off, even though you did everything right.

That's simply because the brain is more advanced than a traditional computer. Funnily enough, a lot of those activities you mentioned as evidence for an immaterial mover of the human mind, are already being done by more advanced artificial intelligence. Isn't that interesting? I mean it gets even more interesting when you realize that even AI developers don't understand the intelligence behind their AI machines but simply the algorithmic process of their intellectual progress, the same is with evolution and neurology. It was an interesting debate and I'm happy to stand my position, thank you.