In June 2012, Robin Hanson wrote a post promoting plastination as a superior to cryopreservation as an approach to preserving people for later uploading. His post included a paragraph which said:
We don’t actually know that frozen brains preserve enough brain info. Until recently, ice formation in the freezing process ripped out huge brain chunks everywhere and shoved them to distant locations. Recent use of a special anti-freeze has reduced that, but we don’t actually know if the anti-freeze gets to enough places. Or even if enough info is saved where it does go.
This left me with the impression that the chances of the average cryopreserved person today of being later revived aren't great, even when you conditionalize on no existential catastrophe. More recently, I did a systematic read-through of the sequences for the first time (about a month 1/2 ago), and Eliezer's post You Only Live Twice convinced me to finally sign up for cryonics for three reasons:
- It's cheaper than I realized
- Eliezer recommended Rudi Hoffman to help with the paperwork
- Eliezer's hard drive analogy convinced me the chances of revival (at least conditionalizing on no existential catastrophe) are good
Note: Signing of this letter does not imply endorsement of any particular cryonics organization or its practices. Opinions on how much cerebral ischemic injury (delay after clinical death) and preservation injury may be reversible in the future vary widely among signatories.
I don't find that terribly encouraging. So now I'm back to being pessimistic about current cryopreservation techniques (though I'm still signing up for cryonics because the cost is low enough even given my current estimate of my chances). But I'd very much be curious to know if anyone knows what, say, Nick Bostrom or Anders Sandberg think about the issue. Anyone?
Edit: I'm aware of estimates given by LessWrong folks in the census of the chances of revival, but I don't know how much of that is people taking things like existential risk into account. There are lots of different ways you could arrive at a ~10% chance of revival overall:
- (50% chance of no existential catastrophe) * (30% chance current cryopreservation techniques are adequate) * (70% chance my fellow humans will come through for me beyond avoiding existential catastrophe) = 10.5%
is one way. But:
- (15% chance no existential catastrophe) * (99% chance current cryopreservation techniques are adequate) * (70% chance my fellow humans will come through for me beyond avoiding existential catastrophe) = ~10.4%
is a very similar conclusion from very different premises. Gwern has more on this sort of reasoning in Plastination versus cryonics, but I don't know who most of the people he links to are so I'm not sure whether to trust them. He does link to a breakdown of probabilities by Robin, but I don't fully understand the way Robin is breaking the issue down.
The brain constructed in your likeness is only normatively related to your brain. That's the point I'm making. The step where you make a description of the brain is done according to a practice of representation. There is no causal relationship between the initial brain and the created brain. (Or, rather, any causal relationship is massively disperse through human society and history.) It's a human being, or perhaps a computer programmed by human beings, in a cultural context with certain practices of representation, that creates the brain according to a set of rules.
This is obvious when you consider how the procedure might be developed. We would have to have a great many trial runs and would decide when we had got it right. That decision would be based on a set of normative criteria, a set of measurements. So it would only be "successful" according to a set of human norms. The procedure would be a cultural practice rather than a physical process. But there is just no such thing as something physical being "converted" or "transformed" into a description (or information or a pattern or representation) - because these are all normative concepts - so such a step cannot possibly conserve identity.
As I said, the only way the person in cryonic suspension can continue to live is through a standard process of revival - that is, one that doesn't involve the step of being described and then having a likeness created - and if such a revival doesn't occur, the person is dead. This is because the process of being described and then having a likeness created isn't any sort of revival at all and couldn't possibly be. It's a logical impossibility.
My response to this is very simple, but it's necessary to know beforehand that the brain's operation is robust to many low-level variations, e.g., thermal noise that triggers occasional random action potentials at a low rate.
Suppose our standard is that we get it right when the reconstructed brain is more like the original brain just before cryonic preservation than a brain after a good night's sleep is like that same brain before sleeping -- within the subset of ... (read more)