You have no way of really understanding the magnitude of endless existential dread or physical pain a disembodied brain might perceive, which I think is the primary concern of ethicists.

In order for these sorts of experiments to be ethical with an apparent consciousness we definitely need BCI technology that can simulate input / output stimuli, at least reasonably.

We don’t know what a brain disconnected from all sensory inputs feels. It could be agonizing pain for all that we know.

It sure seems like patterns of cortical activation (or something like that) could be compared to some sort of waking standard to take a very good measured guess at some point.

Is the implication that pigs don’t experience pain, or that we shouldn’t care?

Pigs have the ability to feel pain. Many people believe we should minimize the undue suffering of sentient organisms.

Some people care about the suffering of animals.

and that makes it ok?

Fear of being blind and alone, unable to even draw a breath to bleat out a cry for help perhaps? Plus, the pig WAS dead. Even if they are just alone with their thoughts, there probably was some trauma surrounding become an ex-pig.

Not all pain is physical: https://en.wikipedia.org/wiki/Psychological_pain

Technically, the medical community only considers physical injury with the term 'pain', but there is growing consensus that pain can be more general (especially considering it is often subjective). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2952112/

Pain exists in the brain, not the body.

All response experience exists within the brain, yes, but it is only ever made possible through external stimulus. The brain itself doesn't feel anything, but generates those feelings as a response to events outside of itself.

"If it seems strange that nerve signals coming from the back can represent vision, bear in mind that your own sense of vision is carried by nothing but millions of nerve signals that just happen to travel along different cables. Your brain is encased in absolute blackness in the vault of your skull. It doesn’t see anything. All it knows are these little signals and nothing else. And yet you perceive the world in shades of brightness and colors. Your brain is in the dark but your mind constructs the light." — David Eagleman in his book Incognito.

Without the nerves connecting your toe to your brain, you are unlikely to feel the otherwise agonizing pain of having had stubbed it against a coffee table.

Phantom limbs can cause/have pain, partly from the lack of expected predicted feedback. I cannot begin to imagine what sort of chaos, in the dynamical sense, a non-existent body would cause and how that would be represented in the parts of the brain that calculates how to interpret it.

Good point!

But parts of those nerves are there; you can't really shave them off, they end inside the brain.

Think of it as taking a microprocessor in a circuit and disconnecting every one of its pins except those providing power. How would that microprocessor behave? It's various I/O pins aren't gone, their state and response just became somewhat random.

Your brain can't hurt, but presumably a phantom body could be made to hurt by providing the right neural stimulation.

No matter how hard I think, I cannot seem to manifest any true pain in my mind. I doubt a pig could either.

Your sensory inputs remained connected at all times. That absence is unprecedented in its whole, but we do know that amputated members can hurt, and not just the stump.

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

Well I'm sure you doing the thought exercise is the same as killing yourself and then reviving yourself 4 hours later to see if you feel any pain, we should all really defer to your scientific ethical expertise in the future.

Just because your brain is where all feelings 'exist' doesn't mean you have the ability to manifest it at will. But the brain does plenty of things to us that we don't want. I don't think excruciating pain would be something a brain-in-a-jar would feel - but it's possible that being deprived of all sensory connections would cause things to get weird quickly. Sort of like phantom limb syndrome!

I don't think it's that hard to imagine that at a minimum a sensation like phantom pain existing in this scenario.

The nerves that feed the brain are severed, that might feel a lot like total pain. The parent's comment wasn't about manifesting pain through thought.

I've been hurt in dreams, in ways that do not appear to have been the real world poking through. It's never been great pain, but it's been real pain or something very close to it. There's also phantom limb syndrome [1]. It's not hard to imagine whatever mechanism is in play there could run even more unfettered when there is no feedback from the body at all.

We do not know that simply being severed from your body is simply experiencing no sensory input of any kind, and actually have a lot of reasons to expect that would not be the subjective experience for very long.

(Bizarrely, the dream pain has nothing to do with anything in real life that should have been pain. Apparently my subconscious is fine with dismemberment or stabbing or whatever, but what really bothers it is removing my orthodontic spacer from the roof of my mouth, which apparently it feels is me trying to remove the roof of my mouth. Subconsciouses are weird.)

[1]: https://www.britannica.com/science/phantom-limb-syndrome

Oh, good point about pain in dreams! I have also experienced this. I used to have a lot of lucid dreams, where I was often aware of being in a dream. I somehow hurt my left shoulder and was suddenly in excruciating pain. I woke up and my shoulder felt just the same as in the dream, very bad. I quickly examined myself for injury and finding nothing, the pain very quickly went away. I guess I cannot say for sure that it was not physical pain leaking into imagination land but that is certainly not how it felt.

Pain is registered by nerves connected to the brain, and given that phantom pain happens even when those nerves are truly gone, its definitely possible the pig brain could interpret it as pain. This is pretty new territory to make strong statements about

Thats not what this means.

Perhaps the fact the the brain was disconnected from the body was a major factor in why no signs of consciousness were recorded. Consciousness may be the byproduct of a living body sending signals to a living brain.

> Consciousness may be the byproduct of a living body sending signals to a living brain.

Might be, but unlikely. Both our medical and legal (executions) experience shows that most parts of the body can be removed or paralyzed without impacting consciousness. It really seems like the obvious model - that the brain alone is the center of consciousness - is the correct one.

Phantom limb can hurt. Phantom body might hurt too.

That's quite the extraordinary claim. Is there any evidence to backup that assertion? As far as I'm aware nobody knows what a living brain detached from the body actually experiences.