Well, it is.

> Our understanding of the fundamental nature of reality (physics) and consciousness (neuroscience/psychology) is still highly theoretical.

It's much more than that. No experiment has ever been done that contradicts either GR or the Standard Model. So unless the operation of the brain depends on new, undiscovered physics, we do in fact have all the information we need in order to completely understand the operation of the brain, at least in principle.

>Well, it is.

Nah, it's much deeper than that as you well know. The word "just" implies there's nothing more to be explained.

>No experiment has ever been done that contradicts either GR or the Standard Model.

The Standard Model is an incomplete theory that fails to explain many physical phenomenon. Let's not pretend otherwise.

>So unless the operation of the brain depends on new, undiscovered physics, we do in fact have all the information we need in order to completely understand the operation of the brain, at least in principle.

So you admit we don't actually know that consciousness is "just neurons firing", you're just extrapolating?

Sure, but atoms are an extremely good approximation to the truth in the regime in which human brains operate.

> The Standard Model ... fails to explain many physical phenomenon.

Yeah? Like what?

> you're just extrapolating?

Of course. Until we have a full understanding of the human brain, there will be things about its behavior about which we must extrapolate (that's what "not having a full understanding" means). But I'm extrapolating from some pretty damned good data and some pretty damned solid math. So I am highly confident in this extrapolation.

>Yeah? Like what?

https://en.m.wikipedia.org/wiki/Standard_Model

>I am highly confident in this extrapolation.

Even still, we shouldn't state theoretical extrapolations as if they are facts. It's the difference between saying "x is caused by y" and "I think x is probably caused by y".