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 problem with the computationalist view is that it confuses the representation with what is represented. No account of the structure of the brain is the brain. A detailed map of the neurons isn't any better than a child's crude drawing of a brain in this respect. The problem isn't the level of detail, it's that it makes no sense to claim a representation is the thing represented. Of course, the source of this confusion is the equally confused idea that the brain itself is a sort of computer and contains representations, information, etc. The confusions form a strange network that leads to a variety of absurd conclusions about representation, information, computation and brains (and even the universe).
Information about a brain might allow you to create something that functions like that brain or might allow you to alter another brain in some way that would make it more like the brain you collected information about ("like" is here relative), but it wouldn't then be the brain. The only way cryonics could lead to survival is if it led to revival. Any account that involves a step where somebody has to create a description of the structure of your brain and then create a new brain (or simulation or device) from that, is death. The specifics of your biology do not enter into it.
Cyan's post below demonstrates this confusion perfectly. A book does contain information in the relevant sense because somebody has written it there. The text is a representation. The book contains information only because we have a practice of representing language using letters. None of this applies to brains or could logically apply to brains. But two books can be said to be "the same" only for this reason and it's a reason that cannot possibly apply to brains.
Suppose a small chunk of your brain is replaced with its functional equivalent, is the resulting chimera less "you"? If so, how can one tell?