But (as far as I can tell) such a definition doesn't explain why we aren't micro-experiential zombies. Compare another fabulously complicated information-processing system, the enteric nervous system ("the brain in the gut"). Even if its individual membrane-bound neurons are micro-pixels of experience, there's no phenomenally unified subject. The challenge is to explain why the awake mind-brain is different - to derive the local and global binding of our minds and the world-simulations we run from (ultimately) from physics.
I wish the binding problem could be solved so simply. Information flow alone isn't enough. Compare Eric Schwitzgebel ("If Materialism Is True, the United States Is Probably Conscious"). Even if 330 million skull-bound American minds reciprocally communicate by fast electromagnetic signalling, and implement any computation you can think of, then a unified continental subject of experience doesn't somehow switch on - or at least, not on pain of spooky "strong" emergence".
The mystery is why 86 billion odd membrane-bound, effectively decohered classical nerve cells should be any different. Why aren't we merely aggregates of what William James christened "mind dust", rather than unified subjects of experience supporting local binding (individual perceptual objects) and global binding (the unity of perception and the unity of the self)?
Science doesn't know.
What we do know is the phenomenal binding of organic minds is insanely computationally powerful, as rare neurological deceit syndromes (akinetopsia, integrative agnosia, simultanagnosia etc) illustrate.
I could now speculate on possible explanations.
But if you don't grok the mystery, they won't be of any interest.
Forgive me, but how do "information flows" solve the binding problem?
Just a note about "mind uploading". On pain of "strong" emergence, classical Turing machines can't solve the phenomenal binding problem. Their ignorance of phenomenally-bound consciousness is architecturally hardwired. Classical digital computers are zombies or (if consciousness is fundamental to the world) micro-experiential zombies, not phenomenally-bound subjects of experience with a pleasure-pain axis. Speed of execution or complexity of code make no difference: phenomenal unity isn't going to "switch on". Digital minds are an oxymoron.
Like the poster, I worry about s-risks. I just don't think this is one of them.
Homunculi are real. Consider a lucid dream. When lucid, you can know that your body-image is entirely internal to your sleeping brain. You can know that the virtual head you can feel with your virtual hands is entirely internal to your sleeping brain too. Sure, the reality of this homunculus doesn’t explain how the experience is possible. Yet such an absence of explanatory power doesn’t mean that we should disavow talk of homunculi.
Waking consciousness is more controversial. But (I’d argue) you can still experience only a homunculus - but now it’s a homunculus that (normally) causally do-varies with the behaviour of an extra-cranial body.
It's good to know we agree on genetically phasing out the biology of suffering!
Now for your thought-experiments.
Quantitatively, given a choice between a tiny amount of suffering X + everyone and everything else being great, or everyone dying, NU's would choose omnicide no matter how small X is?
To avoid status quo bias, imagine you are offered the chance to create a type-identical duplicate, New Omelas - again a blissful city of vast delights dependent on the torment of a single child. Would you accept or decline? As an NU, I'd say "no" - even though the child’s suffering is "trivial" compared to the immensity of pleasure to be gained. Likewise, I’d painlessly retire the original Omelas too. Needless to say, our existing world is a long way from Omelas. Indeed, if we include nonhuman animals, then our world may contain more suffering than happiness. Most nonhuman animals in Nature starve to death at a early age; and factory-farmed nonhumans suffer chronic distress. Maybe the CU should press a notional OFF button and retire life too.
A separate but related question: What if we also make it so that X doesn't happen for sure, but rather happens with some probability. How low does that probability have to be before NUs would take the risk, instead of choosing omnicide? Is any probability too low?
You pose an interesting hypothetical that I’d never previously considered. If I could be 100% certain that NU is ethically correct, then the slightest risk of even trivial amounts of suffering is too high. However, prudence dictates epistemic humility. So I’d need to think some more before answering.
Back in the real world, I believe (on consequentialist NU grounds) that it's best to enshrine in law the sanctity of human and nonhuman animal life. And (like you) I look forward to the day when we can get rid of suffering - and maybe forget NU ever existed.
It wasn't a rhetorical question; I really wanted (and still want) to know your answer.
Thanks for clarifying. NU certainly sounds a rather bleak ethic. But NUs want us all to have fabulously rich, wonderful, joyful lives - just not at the price of anyone else's suffering. NUs would "walk away from Omelas". Reading JDP's post, one might be forgiven for thinking that the biggest x-risk was from NUs. However, later this century and beyond, if (1) “omnicide” is technically feasible, and if (2) suffering persists, then there are intelligent agents who would bring the world to an end to get rid of it. You would end the world too rather than undergo some kinds of suffering. By contrast, genetically engineering a world without suffering, just fanatical life-lovers, will be safer for the future of sentience - even if you think the biggest threat to humanity comes from rogue AGI/paperclip-maximizers.
Do they also seek to create and sustain a diverse variety of experiences above hedonic zero?
Would the prospect of being unable to enjoy a rich diversity of joyful experiences sadden you? If so, then (other things being equal) any policy to promote monotonous pleasure is anti-NU.
Secular Buddhists like NUs seek to minimise and ideally get rid of all experience below hedonic zero. So does any policy option cause you even the faintest hint of disappointment? Well, other things being equal, that policy option isn't NU. May all your dreams come true!
Anyhow, I hadn't intended here to mount a defence of NU ethics - just counter the poster JDP's implication that NU is necessarily more of an x-risk than CU.
You remark that "A physical object implementing the state-machine-which-is-us and being in a certain state is what we mean by having a unified mental state." You can stipulatively define a unified mental state in this way. But this definition is not what I (or most people) mean by "unified mental state". Science doesn't currently know why we aren't (at most) just 86 billion membrane-bound pixels of experience.