Confabulation.

Look at split-brain patients: divide the corpus callosum down the middle, and you effectively have two separate brains that don't communicate. Tell the half without the speech centre to perform some random task, then ask the other one why they did that - and they will flat-out make up some plausible sounding reason.

And the thing is, they haven't the slightest idea that it isn't true. To them, it feels exactly like freely choosing to do it, for those made up reasons.

Bits of our brains make us do stuff for their own reasons, and we just make shit up to explain it after the fact. We invent the memory of choosing, about a quarter of a second after we've primed our muscles to carry out the choice.

I think a chunk of this comes down to our need to model the thoughts of others (incredibly useful for social animals) - we make everyone out to be these monolithic executive units so that we can predict their actions, and we make ourselves out to be the same so we can slot ourselves into that same reasoning.

Also it would be a bit fucking terrifying to just constantly get surprised by your own actions, blown around like a leaf on the wind without a clue what's going on, so I think another chunk of it is just larping this "I" person who has a coherent narrative behind it all, to protect your own sanity.

There was a relevant post on Lemmy the other day:

The origin and nature of existence is an epistemological black hole that some people like to plug with "a ~~wizard~~ god did it".

The sensation of free will is an emergent property of a lack of awareness of the big stuff, the small stuff, the long stuff, and the short stuff.

Here's my take: the answer is emergent phenomena. We live in a very complex system and in complex systems there are interactions that can only be predicted using systems of equal or higher complexity. So even in case everything is predetermined, it would still be unpredictable and therefore your decisions are basically still up to you and the complex interactions in your brain.

If you throw a pair of dice, do they still have to roll if their final positions are predetermined from the point that you let go?

One view is that even a deterministic mind still must execute. An illusion of the capacity to choose between multiple options might be necessary to considering those options which leads to the unavoidable conclusion.

A better question is, is there any difference between the illusion of free will and actual free will. Is there some experiment you could conduct to tell the difference?

Our brains cannot store all the experiences we ever make. It rather only stores 'hunches' (via many weightings of neurons). In particular, it also mixes multiple experiences together to reinforce such hunches.

This means that despite there being causal reasons why you might e.g. feel uneasy around big dogs, your brain will likely only reproduce a hunch, a gut feeling of fear.

And then because you don't remember the concrete causal reasons, it feels like a decision to follow your hunch to get the hell out of there.
This feeling of making a decision is made even stronger, because there isn't just the big-dog-bad-hunch, but also the don't-show-fear-to-big-dog-hunch and the I'm-in-a-social-situation-and-it-would-be-rude-to-leave-hunch and many others.

There is just an insane amount of past experiences and present sensory input, which makes it impossible to trace back why you would decide a certain way. This gives the illusion of there being no reasons, of free will.

Maybe look up "compatibilism". It's a philosophy proposing that both exist.

You're conscious of the decisions you make. Sure they're the result of a million different variables, chemicles, memories, and predetermined traits, but some of that is active. You are making the choice. Whether you could have made a different one or not doesn't affect what the choice feels like

Honorary mention, Kurtzgesagt/In a Nutshell https://youtu.be/UebSfjmQNvs?feature=shared

For the same reason that I feel like I'm still right now, while I'm actually spinning and hurtling through space at incredible speed.

The most accurate answer is: We don't know.

But there are pieces of scientific evidence that suggest our sense of free will is just another perception process that happens in our brains. Specifically I'm thinking about people who have problems in their brain that make them feel like they AREN'T the one controlling what they do. For example people suffering from derealization - https://www.mayoclinic.org/diseases-conditions/depersonalization-derealization-disorder/symptoms-causes/syc-20352911

EDIT

As to why our brains have a process that gives us a perception of free will, that's a much harder question that i think science currently only has conjecture on. If i had to guess I'd guess that either there's an evolutionary advantage to it, or it's an emergent property that arises from all the parts of the brain being connected in the way they are

I forget which philosopher said this but he said something along the lines of if you have the desire and the capacity for an action you do, then deterministic or not, you chose that action. If the tide pulls me where I was already swimming, I still chose to swim there, even if some other force took me half of the way.

Just going to throw out a really good read: Determined by Robert Sapolky. (Behave is also really good.)

He doesn't really convince me of the core thesis that free will doesn't exist, or that some of his proposed changes to the legal system to "recognize the absence of free will" in the second half are good courses of action, but he does do a great job of demonstrating what makes us tick from a variety of lenses, how much environmental factors play a role in behavior, and generally arguing to approach people with more empathy and recognition that we might be more like them in a similar situation than we think.

(It is heavy. It's long and goes into some depth on different fields. But he lays out the main ideas you need to know and doesn't assume that much knowledge, just a will to learn.)

I have heard somewhere that some people seemed to believe that behind each human's actions, there is some kind of "daemon" that is invisible, but moving the humans like puppets.

This is conceptualized in the theater mask, through which one can speak.

The daemon speaks through the human as a theater actor would speak through a mask. (The latin word for that mask is "persona" (literally "sound-through") and that's why we call a person a person today (because they are controlled by a daemon who speaks through them)).

Roger Penrose is pretty much the only dude looking into consciousness from the perspective of a physicist

He thinks consciousness has to do with "quantum bubble collapse" happening inside our brains at a very very tiny level.

That's the only way free will could exist.

If consciousness is anything else, then everything is predetermined.

Like, imagine dropping a million bouncy balls off the hoover dam. You'll never get the same results twice.

However, that's because you'll never get the same conditions twice.

If the conditions are exactly the same down to an atomic level... You'll get the same results every time

What would give humans free will would be the inherent randomness if the whole "quantum bubble collapse" was a fundamental part of consciousness.

That still wouldn't guarantee free will, but it would make it possible.

There's also the whole thing where what we think of as our consciousness isn't actually running the show. It's just a narrator that's summarizing everything up immediately after it happened. What's actually calling the shot is other parts of our brains, neurons in our gut, and what controls our hormones.

We don't know if that's not true either. But if it was, each person as a thing would have free will, it's just what we think of as that person does not have free will.

Sounds batshit crazy and impossible, until you read up on the studies on people who had their brains split in half at different stages of mental development.

There's a scary amount of shit we don't know about "us". And an even scarier amount we don't know about how much variation there is with all that

Assuming we don't have free will, why do we have the illusion that we do?

You experience the world through your senses.

What sense that your body has would you expect to give your brain a different set of inputs if your brain's actions were not deterministic, not set by the laws of physics? How would you expect it to feel different?

You wouldn't expect to feel like some invisible force is in control of your limbs, which I think is perhaps what some people intuitively expect if someone says that their actions are pre-determined.

It's not talking about anything that your brain can sense; it's talking about how your brain works.

I personally think the debate over the existence of Free Will is simply an extraordinary debate over semantics.

If you look at a human being from its basic biological and cellular makeup, a human being is a walking bundle of competing desires that appears to present itself as a single cohesive corporate entity.

The people who are against the concept of free will say that because you have innate desires for food sex and entertainment, that you have no choice to not act upon those in a desires and therefore any delusion that you carry about the choices that you make being done of an entirely unencumbered and Free Will are false.

Then there are people who say that Free Will doesn't exist for religious purposes, that God is an all-knowing creature who knows the beginning and the end and everything in between and so you cannot make a choice that he or she or it does not already know that you will make and therefore your choices are not free.

The people who say Free Will does exist on a biological level will point to people who choose to self-immolate or to starve themselves to death in protest of a spiritual or psychological issue, valuing the ideals that life has imprinted upon them over the biological necessities of continuing to live.

The people who say Free Will does exist on a spiritual level say many things, such as we carry a spark of the Divine in us and therefore we are as little gods ourselves, capable of creating and destroying in roughly the same proportional magnitude as the greater gods above are, or they say that since we have the ability to make choices and we are judged by those choices than our choices must be free otherwise judgment is meaningless.

I personally tend to lean into the Free Will side, while understanding simultaneously that sometimes there are exigencies that induce us to choose one option over another on a more likely than not basis, or to phrase it another way, our will is as free as we choose it to be.

Anyone who says we don’t have free will can come up with a thousand reasons we don’t.

Anyone who says we do have free will can come up with a thousand reasons we do.

It really doesn’t matter. All I know is that if I wanted to go on a murderous rampage, I could. I choose not to. For me, that means that I currently have control over myself and my actions. And on the same token, there is so much outside of my control that affects my trajectory in this life.

So there are illusions if you allow there to be. To me, we both have and don’t have free will depending on context.

I call this phenomenon, Schrödinger’s Destiny.

If I found out that I don't have free will, I would start trying to gain it back immediately.

The Matrix deals with the exact question.

I enjoy either the free will or the illusion thereof not to torment myself with such unanswerable questions!

Because it's not an illusion.

Determinism seems reasonable only because people have an inaccurately simplistic conception of causation, such that they believe that consciousness and choice violate it, rather than being a part of it.

Causation isn't a simple linear thing - it's an enormously complex web in which any number of things can be causes and/or effects of any number of things.

Free will (properly understood) is just one part of that enormously complex web.

I think its because we're only just now coming to terms with the fact that we're simply a collection of desires, the culture we were born to and stories we tell ourselves. In keeping, we had to have a story to tell ourselves and free will existing is the more compelling of the two.

I don't think there's an evolutionary purpose. To me, we just became far more self aware than our limited knowledge of the world we find ourself in could cope with and its more of a coping mechanism than anything else.

Yes, there's an evolutionary purpose for the concept of purpose. If you believe you can do something and show some initiative then you're more likely to get it. The early bird gets the worm, and the bird that anticipated the worm is the early bird. This is true both for humans and cells in a petri dish.

Things can be true on different levels and false on others. The earth is locally flat, it is as a whole a near sphere.

I don't know if we have free will or not, I strongly suspect that physics can explain our minds fully, but I don't know. At the same time even if physics could fully explain our minds in practice we are so complicated we give the impression that we have a limited amount of free will. So yeah the earth is round but it is easier for us to assume flat most of the time.