I looked at my old post Zombies! Zombies? and it seemed to have some extraneous content. This is a redacted and slightly rewritten version.

Your "zombie", in the philosophical usage of the term, is putatively a being that is exactly like you in every respect—identical behavior, identical speech, identical brain; every atom and quark in exactly the same position, moving according to the same causal laws of motion—except that your zombie is not conscious.

It is furthermore claimed that if zombies are "conceivable" (a term over which battles are still being fought), then, purely from our knowledge of this "conceivability", we can deduce a priori that consciousness is extra-physical, in a sense to be described below.

See, for example, the SEP entry on Zombies. The "conceivability" of zombies is accepted by a substantial fraction, possibly a majority, of academic philosophers of consciousness.

I once read somewhere, "You are not the one who speaks your thoughts—you are the one who hears your thoughts".

If you conceive of "consciousness" as a quiet, passive listening, then the notion of a zombie initially seems easy to imagine. It's someone who lacks the the inner hearer.

Sketching out that intuition in a little more detail:

When you open a refrigerator and find that the orange juice is gone, you think "Darn, I'm out of orange juice." The sound of these words is probably represented in your auditory cortex, as though you'd heard someone else say it.

Why do I think the sound of your inner thoughts is represented in the auditory cortex, as if it were a sound you'd heard? Because, for example, native Chinese speakers can remember longer digit sequences than English-speakers. Chinese digits are all single syllables, and so Chinese speakers can remember around ten digits, versus the famous "seven plus or minus two" for English speakers. There appears to be a loop of repeating sounds back to yourself, a size limit on working memory in the auditory cortex, which is genuinely phoneme-based.

It's not only conceivable in principle, but possibly possible in the next couple of decades, that surgeons will lay a network of neural taps over someone's auditory cortex and read out their internal narrative. Researchers have already tapped the lateral geniculate nucleus of a cat and reconstructed recognizable visual inputs...

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