p-zombies

We speak of "hearing" our internal voices, and scientists have seen activity in the brain's auditory cortex when we do. Apparently we've also been able to reconstruct images from a cat's visual cortex, seeing what it sees.

One day, we'll likely be able to read back someone's internal monologue.

That's useful to know in the p-zombie thought experiment, which tries to eliminate dualism without eliminating it. It's the idea that you could have a world where all the people behave exactly like people in our world, but nobody is home in their heads to experience things – no "soul" so to speak. Philosophical zombies. Pretty much what René Descartes (1596–1650) thought of non-human animals, but extended to claim that the very fact that people go around talking about feelings still isn't proof that they experience any.

But in this purely "mechanical" world where nobody's actually experiencing anything—where there's nobody we would think of as alive—why would the p-zombie have an internal voice, and talk to other p-zombies about how they experience their internal voice?

Dissolving the thought experiment gets very deep, so I'm stopping here.

Conclusion

If you skimmed the above summary, you might get the idea that the conclusion would run along the lines that there must be "a ghost in the machine", that-which-experiences, a soul, but the conclusion is the opposite! We can see the experiences in the lab: the auditory cortex, made of material cells, very much part of this world, does some work which is the sensation of an internal voice.

In other words, the p-zombie is an impossible postulate because the material world is sufficient to create experiences. If the material world is sufficient to create experiences, there's nothing left for a soul to do. What's it there for?

It's rather the belief in souls (dualism) that requires also claiming that p-zombies are possible, so that the soul can be said to add something.