Thanks! Yes, chapter 8 is essentially an overview of how QALY calculations are performed in health economics and how brain preservation techniques fare against other therapies. Lots more details there.

Weird that the erasure link isn't working for you, it works fine when I click on it? Either way, the paper is: https://www.nature.com/articles/nature15257 'Labelling and optical erasure of synaptic memory traces in the motor cortex'

Yeah, as I see it, the motivations to pursue this differ in strength dramatically depending on whether one's flavour of utilitarianism is more inclined to a person-affecting view or a total hedonic view.

If you're inclined towards the person-affecting view, then preserving people for revival is a no-brainer (pun intended, sorry, I'm a terrible person).

If you hold more of a total hedonic view, then you're more likely to be indifferent to whether one person is replaced for any other. In that case, abolishing death only has value in so far as it reduces the suffering or increases the joy of people who'd prefer to hold onto their existing loved ones rather than have them changed out for new people over time. From this perspective, it'd be equally efficacious to just ensure no-one cared about dying or attachments to particular people, and a world in which everyone was replaced with new people of slightly higher utility would be a net improvement to the universe.

Back in the real world though, outside of philosophical thought experiments, I suspect most people aren't indifferent to whether they or their loved ones die and are replaced, so for humans at least I think the argument for preservation is strong. That may well hold for great ape cousins too, but it's perhaps a weaker argument when considering something like fish?

Thanks Andy for writing this up! I have two comments:

1. For those interested in a longer yet accessible treatment of this topic written for a general audience, I've got a book coming out on this in November - The Future Loves You: How and Why We Should Abolish Death. It covers much of the medicine, neuroscience, philosophy, and economics that Andy already touched on in this post, plus more besides.

2. One thing Andy didn't touch on and that I don't cover in my book is that the ethical imperative of brain preservation seems to be very different based on whether one holds a 'total hedonic' view or a 'person-affecting' view of utilitarianism. In a total view, the particular individuals having the happy experiences don't matter, just that there are happy experiences being had. In the person-affecting view, one cares more that particular people have happy experiences, and it would be bad if everyone on Earth suddenly ceased to exist and were switched out for completely new people of equal or greater total happiness. I think "normal" people tend towards a person-affecting view, while effective altruists typically tend towards a total view. I'd be curious to see a formal analysis of how brain preservation fits into these views though.

Thanks! The link to Ara & Brazier (2010) is particularly helpful, as Figure 1 contains the information I need to calculate it for at least a UK citizen. 

UK life expectancy is ~80. Eyeballing the figure suggests those <30 accrue ~0.95 QALYs/year, while those from 30-80 accrue ~0.85. Putting that together would suggest ~71 undiscounted QALYs, which agrees with your estimated of 70.

I'm aware that this is an extremely crude and rough way of doing things, but it's still helpful as a sanity check for the problem I'm currently working on. Thanks again!

A simple yet inspiring post, much like the good work that you have wrought. Good job Henry!

As per usual, Scott Alexander has a humorous take on this problem here (you need to be an ACX subscriber).

But as a general response, this is why we need to try and develop an accepted theory of consciousness. The problem you raise isn't specific to digital minds, it's the same problem when considering non-adult-human consciousness. Maybe most animals aren't conscious and their wellbeing is irrelevant? Maybe plants are conscious to a certain degree and we should be concerned with their welfare (they have action potentials after all)? Open Philanthropy also has a report on this issue.

For the moment, the best we've got for determining whether a system is conscious is:

• Subjective reports (do they say they're conscious?)
• Analogous design to things we already consider conscious (i.e. adult human brains)

The field of consciousness science is very aware that this is not a great position to be in. Here's a paper on how this leads to theories of consciousness being either trivial or non-falsifiable. Here's a debate between various leading theories of consciousness that is deeply unsatisfying in providing a resolution to these issues.

Anyway, this is just to say there are a great deal of problems that stem from 'we don't know which systems are conscious' and sadly we're not doing a great job of being close to having a solution for that.

The short reply to this is that there are already circumstances where people have brains that have completely ceased all (electrical) activity and we don't normally consider people who've gone through these processes to have been "destroyed" and then "recreated". 

This can happen in both cold-water drowning and in a surgical procedure called deep-hypothermic circulatory arrest. In both circumstances, a person's body temperature is brought below 20C and their brain completely stops all electrical activity for ~30 min. When later brought out of this state, people retain their memories and sense of personal identity. Nobody typically treats these people as 'mere copies' of their previous selves.

Anyway, it's a reasonable question and not a "non-issue", but this plus other considerations make it seem not so problematic. Another consideration is the fact that over time you replace essentially all the components of your body through consumption and excretion, so survival can't be based purely on physical continuity either.

Thanks for the effortful post Andy! I agree so strongly with the importance of exploring this topic that I am halfway through writing a book on the subject. I'll respond to the technical points first, than the ethical ones.

Regarding some of the technical points:

• Cryopreservation with cryoprotective agents, but without prior aldehyde fixation, produces unavoidable brain shrinkage of around 50%. Although it's possible that all important structural and biochemical information survives this shrinkage, it's very plausible that critical synaptic connection information will be lost due to non-uniform shrinkage, tearing or receptor hyperconcentration. Perhaps its better than no option at all, but aldehyde-stabilised cryopreservation provides a much higher guarantee of successful information preservation.
• The long-term storage costs of an aldehyde-preserved brain is currently an open question, as we're unclear on how cold a brain has to be kept to prevent lipid drifting over the long-run. You do need to keep the brains below room temperature, as otherwise the lipids in the neuron cell membranes will slowly drift and obscure your synaptic information. However, it might be possible to slow this sufficiently at only -20C or so, which will make it much cheaper than the current requirement of -135C.
• The point of information-theoretic death relative to current legal death very much depends on the condition of the patient during their final dying phase. For someone who suffers a sudden unexpected cardiac arrest, but who was otherwise healthy previously, evidence from the time to synapse degradation following loss of blood supply suggests it may be around 21 hours. For those who already had extensive health issues including poor circulation and liver failure, it may be much sooner. If you're interested, see my sample chapter below on 'What is Death?'

Regarding the ethical points, I mostly just agree with your comments. Deciding whether lives are fungible is a key part of the debate between 'person-affecting' and 'total' utilitarians, and as of-yet unsettled as I see it in the EA community. Even if one takes the total view though, your points that 1) 'people don't like dying' and 3) 'it might improve their long-term planning' are very compelling. 

I strongly agree with the comment Robin Hanson made as well that the current paucity of uptake both reduces the  chances of neuropreservation being successfully implemented (due to a lack of robust infrastructure and auditing) and makes everything far more expensive (due to a lack of economies of scale). I'm fairly certain that at mass scale the preservation procedure could be done for <$5000 and the storage costs would be only a few dollars per year, meaning that it would certainly be a competitive intervention.

If any comment readers are interested in reading a bit more on this, here are two sample chapters from my upcoming book: '1. Why Don't We Get More Time?' and '6. What Is Death?'. Also, I'm currently in the process of looking for a literary agent to get a publishing house to take up my book proposal, so please PM me if you know any agents who would be interested.

Holden, have you had a look at the Terra Ignota series by Ada Palmer? It's one of the better explorations of a not-quite-Utopia-but-much-better-than-our-world that I've come across, and it certainly contains a large degree of diversity. It also doesn't escape being alien, but perhaps it's not so alien as to lose people completely. My one caveat is that it is comprised of four substantial books, so it's quite the commitment to get through if you're not doing it for your own leisure.

I strongly second this