> specifying the wave-function at any one point in time is enough to specify it for all of time via evolution by the Schrödinger equation.

Scientifically this is not very correct when you consider the chaos theory, which has been widely accepted by physicists for many decades now.

The problem is in practical application (and we live in a practical world, right?). The thing is that in theory, yes you can have some equation or elaborate mathematical model about the world and calculate everything. But once you start doing it, you immediately will see that it is impossible to calculate anything to such precision that this would work, the world is so big and complex that to calculate an X amount of world into the future, you would need Y (>X) amount of world to host those calcaultions. This is only the tip of the iceberg of why that is impossible.

So in practice, it is impossible to "specify it for all of time".

This is not just some logical trick, this is an important difference.

It's the same principle that applies in the Turtle-Achilles paradox (https://en.wikipedia.org/wiki/Zeno%27s_paradoxes).

In the perfect logical world of perfect science and nice beautiful theories and equations - Achilles can never possibly reach the turtle. And yet in the physical reality that we live in it's obvious to anyone (and is truthful) that Achilles will easily reach and overrun the turtle.

On a related note, what is your definition of free will? People with similar SamHarris-esque arguments seem so happy that they have proven that there is no "free will", and yet it seems they have a difficult time defining what it is they have proven? Isn't this a problem if they are trying to be scientific? Would a perfect scientist ever entertain such vague concepts?

"intrinsic notion that humans can directly dictate their own actions" is very vague. Specifically, I can't see any place where even perfect determinism would conflict with this notion: a human is a very complicated deterministic neural network, that analyses the world and does some actions. This whole network processes information, and makes decisions based on that information. Based on that information it does directly dictate it's own actions. Of course those actions are going to be in part based on external information, but in part on the structure and form and function of the network itself. You're not going to find any single neuron that decides everything, but it's very clear that the whole network decides things.

Do you have a disdain for the fact that actions are being based on external stimulus? That this somehow is a problem for free will existing? But of course we would want them being based on external stimulus, that surely must be a part of being sentient? Reacting to something that happens in the world, not just blindly "choosing" random things for the sake of choosing?

And of course "based on external stimuli" - does not mean that the way it's going to react to them it "pre-determined" by something. The network can choose to react to stimuli from right now, or from yesterday, or from some other part of memory, or even from it's own thoughts or definitions. Those are also stimuli. It's obvious to any sentient human that sometimes we do react and act based on such things, not simply on currently active external stimuli.