According to Einstein, if you knew all the variables of a given system, then you would be able to know how that system will be in the future an therefore there would be no free will. This is called “determinism” and it’s a whole discussion in physics.
Heisenberg with his idea of quantum mechanics, whereby things at the quantum level aren’t deterministic but rather built on probabilities, blows this idea of determinism. It suggests that it is not possible to know everything about a system, we can only know the probabilistic wave function that eventually collapses down to a range of probable outcomes. Ie, you can know the location of a quantum particle, or the momentum, but not both. This leans towards the world view of non-determinism, to which Einstein famously said “I don’t believe God plays dice [with the creation]”
So in the realm of physics, it’s still an open question based on the two above fundamentals. Not based on what “I think” or “you think” but ‘currently observable phenomena’.
There have been experiments that seem to demonstrate that our body acts before we are conscious about making that decision to act, suggesting that we are more observers of our actions than the ones choosing to do what we’re doing.
My personal view is:
1) What will happen has already been determined
2) You are fully accountable for your actions because you have free will to make choices, even if outcomes (and even your actions) are outside of your control
3) “You have only been given a little bit of knowledge” - Quraan. So because there is an absolute hard ceiling to our knowledge, what science tells us today and in the future will never gain, for us, absolute knowledge, and there will always remain things that are a mystery to us. As long as we cannot know certain things means we will always have to make choices about what to do and will always remain in the dark about outcomes.
“But how can we have free will if everything is determined?”
That last part. “You have only been given a little bit of knowledge”. You’re expecting to know and understand something you fundamentally cannot. But right now, you are choosing to pick up the phone and read these messages. That choice is observable. You know it exists without debate. But the physical world is governed by rules that, by those rules, allows future events to be known (if you knew all variables, which you and I don’t). Both realities exist. We know it exists but we can’t understand how. That’s like a lot of things. There are many things we don’t know and can’t, and there’s no debate about it. There a famous statement in physics about quantum mechanics “if anyone tells you they understand it, they are lying. Just shut up and calculate”.