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.
I wouldn't say that a brain transplant is nothing at all like a heart transplant. I don't take the brain to have any special properties. However, this is one of those situations where identity can become vague. These things lie on a continuum. The brain is tied up with everything we do, all the ways in which we express our identity, so it's more related to identity than the heart. People with severe brain damage can suffer a loss of identity (i.e., severe memory loss, severe personality change, permanent vegetative state, etc). You can be rough and ready when replacing the heart in a way you can't be when replacing the brain.
Let me put it this way: The reason we talk of "brain death" is not because the brain is the seat of our identity but because it's tied up with our identity in ways other organs are not. If the brain is beyond repair, typically the human being is beyond saving, even if the rest of the body is viable. So I don't think the brain houses identity. In a sense, it's just another organ, and, to the degree that that is true, a brain transplant wouldn't be more problematic (logically) than a heart transplant, provided the dynamics underlying our behaviour could be somehow preserved. This is an extremely borderline case though.
So I'm not saying that you need to preserve your brain in order to preserve your identity. However, in the situation being discussed, nothing survives. It's a clear case of death (we have a corpse) and then a new being is created from a description. This is quite different from organ replacement! What I'm objecting to is the idea that I am information or can be "transformed" or "converted" into information.
What you're saying, as far as I can tell, is that you care more about "preserving" a hypothetical future description of yourself (hypothetical because presumably nobody has scanned you yet) than you do about your own life. These are very strange values to have - but I wish you luck!
Though, now that I think about it...
Wait up. On your account, why should we call those things (memory loss, personality change, loss of cognitive ability) "loss of identity"? If something that has my memories, personality, and cognitive abilities doesn't have my identity, then it seems to follow that something lacking those things doesn't lack my identity.
It seems that on your account those things are no more "loss of identity" than losing an arm or a kidney.