"I will not discuss this with you until you tell me what you mean by 'Free Will'"
Anything else leads to endless semantic quibbling and ducking from one argument to another to defend an ill-defined idea that the person is attached to defending.
While everything works on the same rules we definitely have not arrived at the completion of a list of those rules especially when it comes how biologic systems take advantage those rules to build systems. Its inherent in systems that they allow for increased complexity beyond what the base components allow. Its not a stretch to theorize that increased complexity and the opaque nature of physical interactions might allow space for Free Will or independence of consciousness in certain circumstances.
Comparatively, I think free will is essentially asking that a computer take inputs and it's programming and shrug that all off to come up with a completely novel output.
That's why with exactly the same inputs, the output can actually differ. Whether or not that's free will is another discussion, but the "we are a very complex yet in theory predicable computer" argument doesn't hold.
Moreover, in such systems, the output might be impossible to predict based on the input (other than by running the system).
Deterministic doesn't necessarily imply predictable.
I'm just saying, you don't need to reach for quantum mechanics here, living organisms (and computers) are quite capable of being unpredictable even without it.
For the rest I agree with you.
A computer is entirely capable of generating novel (enough) output. Elsewhere I point to the trivial-seeming python function math.random(). Good luck predicting what that will do!
In reality, it turns out that math.random() and the theory behind PRNGs is not so trivial at all, and is actually quite interesting to dive in to. [2]
[1] This particular argument inspired by https://journals.plos.org/ploscompbiol/article?id=10.1371/jo... . It mentions using neuroscience to try to understand space invaders, which I think is funny. :-)
[2] https://en.wikipedia.org/wiki/Pseudorandom_number_generator , or eg. https://en.wikipedia.org/wiki/Logistic_map being used as an early PRNG
PRNGs are not-quite-random, they're actually chaotic functions.
Which is actually a bit closer to how I think free will functions if you look at it empirically from the outside. (At least: if you were to use your <free will> to try to generate 'random' numbers; which will also not be perfectly random!)
Of course, it does sort of depend on your definition of <free will>.
We can't, so at the moment it looks as though the universe might have true randomness (I'm very sceptical of this).
But even then, so what? Does that mean free will is just decisions with some true universal randomness thrown in? How does that give you free will if it is just random? And then we're back to, what does free will even mean.
To me it basically comes down to infinite butterfly effects where the knowledge of past/current states of the environment can't be effectively used to predict the output of the self.
Another fun way to imagine it is to say 'I' is the complex gut microbiome that's interchanged and evolving and it's the 'source' of decisions more than anything else. It would also solve the problem of how the human population keeps increasing but souls are discrete and countable--even with reincarnation the number of creatures varies greatly. With microbiomes they can be cultivated and/or subdivided, and mixed. Of course this doesn't work out, but it's easy to see there are things that we haven't considered yet to be ruled out.
Space for what? What is free will? Is it just throwing some randomness into decision making?