> Is it possible that alongside the conscious experience of “me,” there is a much dimmer experience of each individual neuron?
No.
No.
One can have a legitimate debate about 48, 70 and 99 being big numbers. But not 30, 28 or 19.
In common parlance, "big" and "small" are often used in context where the thing being related is implied, and usually taken to be a human being. Mountains are big (relative to humans) and ants are small (relative to humans). But ants are big relative to atoms and mountains are small relative to planets.
But "conscious" isn't a relation, it's a property. Normal humans are conscious. Rocks are not. This is not to say that consciousness might not be a continuous property rather than a dichotomy; it almost certainly is. Nonetheless, there is a point at which the degree of consciousness in a system is indistinguishable from zero, at which point it is no longer useful to say that the thing is conscious.
It would make "unconscious" a synonym for "non-existent".
> If a fertilized egg is not conscious, when precisely does it emerge, and what does that transition entail?
No one knows the answer to that. But it's pretty clear to me that consciousness supervenes on brains, so having a brain (or functional equivalent) is a necessary (though not sufficient) condition for being conscious.
Maybe a synonym for “non-physical”, conceptual, or abstract. Why do you say that like it’s some kind of paradox?
> No one knows the answer to that.
Then how does one know it to be true?
> But it's pretty clear to me that consciousness supervenes on brains
Why? No one has ever borne that out.
I'm not. I'm just saying it robs the word "conscious" of most of its utility. It no longer makes sense to say, for example, "That person is unconscious."
> Then how does one know it to be true?
How does one know what to be true?
> Why? No one has ever borne that out.
Then I propose we do the following experiment: let's surgically remove your brain and see if afterwards you still profess to be conscious.
Consciousness is a matter of degree, and there's no hard evidence about how low the scale goes.
No, I'm not. Consciousness is a continuum, not a dichotomy. There are nonetheless systems whose degree of consciousness is indistinguishable from zero.
> there's no hard evidence about how low the scale goes.
Of course there is. It goes down to zero. Rocks are not conscious. Dead people are not conscious. Even humans under general anesthesia are not conscious.
Yes.
> If so, how can you be certain?
I can't be absolutely certain of that nor of anything else. The philosophical-zombie hypothesis cannot be ruled out by evidence. But I observe others producing complex I/O behavior that is qualitatively similar to that which I produce and that I attribute to my own consciousness. I also see evidence that my consciousness supervenes on the operation of my brain, and I observe that other people have brains. The most parsimonious explanation for all that is that other humans are also conscious.
Nope.
> Can we construct one from legos in an aircraft hangar?
Almost certainly not. We can't even construct one on a silicon chip (yet).