You react to choices the specific way you do because of experiences you’ve had previously.

Reverse time without changing anything, you’ll always make the same choices because you’re having the same thoughts each time every time, because you’ve been conditioned the way you are.

The universe doesn’t “know” where it’s going, but the plan is already in action. You can choose whatever you want to do, but if you were the same person in the same circumstance, you would and will always make the same decision.

My brother and I have been having an ongoing debate about this and Simulation Theory for a good few years.

In my mind, it’s a pointless question to try and answer. It makes for a nice thought experiment, but actually having a belief in it is useless.

I think it’s more complicated than free will existing or not.

If you knew every single possible value about the universe at its start and had a perfectly accurate model of physics, you could theoretically predict/simulate everything that would ever happen. For practical reasons, though, that’s impossible, even ignoring weird quantum effects, for the simple reason that that is a lot of data points, more than any of us could reasonably keep track of- it’s like how, in sufficiently controlled conditions, a fair dice can roll the exact same number 100% of the time, but there are enough variables that are hard enough to control for in a normal situation that it’s basically random.

Similarly, if you knew everything about every human on Earth, you could theoretically predict exactly what any of them would do at any given moment. Of course, that’s just not practical- the body and brain are a machine that is constantly taking in input and adapting to it, so in order to perfectly predict someone’s thoughts and actions, you’d need to know every single detail of every single thing that has ever happened to them, no matter how small. Then, you’d need to account for the fact that they’re interacting with hundreds of other people, who are also constantly changing and adapting. It’s just not possible to predict or control a person for any reasonable length of time like that, because one tiny interaction could throw off the entire model.

Just look at current work with AI- our modern machine learning algorithms are much more well-understood and are trained in much more contained environments than any human mind, and yet we still need to manually reign them in and sift through the data to prevent them from going off the rails.

So, technically, I suppose free will doesn’t exist. For practical purposes, though, what we have is indistinguishable from free will, so there’s not much point getting riled up about it.

I have the feeling most people cling to free will as a concept because not having free will raises questions if a “self” truly exists. However the existence of free will can be as scary if not more, since how could we define a “self” if it could freely do something not based on what defines it.

The question is underspecified. Why do you want to know if free will exists? What will you do differently if it does exist vs if it does not exist?

This is similar to questions like, “is water wet?” You can generate endless debate on the topic, but it’s all intellectual masturbation until you are genuinely looking for the answer to a specific question.

Hard determinist here. It doesn’t make the future predictable by me, but I don’t see how randomness could really occur. And then likewise there’s no such thing as free will.

Quantum mechanics are probabilistic, which serves as a good argument for the universe as a whole being probabilistic. The position of a single particle could change a great many things!

For me, I’ve always struggled with the definition of free will. Is there even a will to be free? The voice in my head is just a story “I” tell myself. So really, I’m just this conscious presence. I can observe thoughts that manifest within that presence. But those thoughts aren’t under my control. They’re just occurring.

I remember watching a video from Sam Harris years ago that really brought this to the forefront. Think of a movie. Any movie. What is it? Why did you pick that movie? Did you have conscious control over what movie you picked? Or did it just pop into your consciousness?

Either everything is purely deterministic, purely random, or something in between. But on that spectrum, there really isn’t room for free will. Simply the illusion of it.

So that’s a topic that fascinated so many people forever.

With all these people fascinated by it, some of them weirdos put their whole life’s at it.

And these weirdos came to a few absolutely terrifying conclusions:

1. The ultimate future is predictable: 2nd law of thermal dynamics means the universe will eventually end with energy being equal everywhere, so there is nothing because there is no difference. That’s the heat death of the universe.

2. Otherwise nothing is absolutely predictable: the uncertainty principle says you can either know the precise position of a particle, or you know the precise movement of a particle, you can’t know both at the same time. So yeh if you know the initial condition you can make a prediction, but you can’t know the precise initial condition at particle level, and since the world is made of particles, you can only make imprecise predictions without 100% certainty.

You could argue that the human mind is a quantum machine. You don’t know it’s initial condition. Nor do you know the precise initial condition of every human mind in the world. The impreciseness of any prediction, even if it could be small individually, adds up in the scale of the world, the universe. So that can be you foundation of free will, up to the heat death.

The concept of belief is rooted in free will, is it not?

Here is a good lecture from Robert Sapolsky on Human behavioral biology that will replace your question with more questions:
https://www.youtube.com/watch?v=NNnIGh9g6fA

The licanius trilogy explores this really nicely. If you’re a sci-fi or fantasy fan I really do highly recommend them.

Hopefully without spoiling too much, the future being predetermined doesn’t necessarily prohibit free will. In the same way we can’t travel backwards in time we can’t travel forwards faster. Everything has happened, both in the past present and future, but it’s still the decisions of the people that led to and lead to the outcomes that exist. The past is just as postdetermined as the future is predetermined, if that makes any sense.

It’s weird but I liked it.

Now see, if you’re looking at things from a biological point of view, it’s important to recognize the forest from the trees. A few trees are, well, just a few trees. But a great many trees together constitutes a forest, and becomes more than the sum of its parts. I feel the same way about the human brain. Yes, it’s a series of electrical and chemical impulses, but there are so many of these working in tandem that it becomes exponentially more complex, akin to ever-advancing computer technology. It’s complex enough that we think, we talk, we make decisions. And those decisions aren’t based solely on instinctional drive, and can even be made in opposition to them.

It’s true that human behavior can be accurately predicted based on an individual’s natural tendencies, but there are never any guarantees. There’s always a choice, a chance to veer off course. Decisions can be prudently made after careful research, or made on a frivolous impulse. Maybe you even realize that you would ordinarily take one action in a given situation, but do the exact opposite. You consciously chose to ignore your first impulse. If free will is an illusion, it’s a damned convincing one.

I just wanted to say that if you guys truly want to see what serious answers can be given to these type of questions you can always take a look into philosophy and just so happens I’m trying to build a philosophy community on Kbin so feel free to check m/AskPhilosophers, and m/LearnPhilosophy.

I think the universe is deterministic, but also that absolute prediction is impossible and that there might even be actually random events in it (or not, I’m just not certain either way about that part). Even if you have an absolutely random uncalculatable die tho, that doesn’t mean the future is not predetermined. If hypothetically I had a time machine, rolled the die, recorded the result, and then went back to before it was rolled, then watched the roll again, then if it always gets that same result, despite not being “caused” by any external factors, then the universe would still be deterministic even with the presence of randomness