daniel_the_smith wrote:Probabilities:
P(positive singularity) = 20%
...
P(reanimation|~positive singularity) = .0001%
...
And on difficulty: I expect successful reanimation requires on the order of thousands of years of time for a human-level intelligence with access to nanotechnology. (There are on the order of 100 trillion axions/dendrites that need to be examined for breaks, and probably other things to fix also; you do the math!) I do not expect people to be reanimated until THAT costs less than running a refrigerator. Once you wrap your mind around how difficult it will be to unfreeze someone, I think the things I'm claiming about societies capable of such feats become a lot easier to swallow.
Well, we agree on
one of those probabilities, give or take an order of magnitude.
I can't imagine having a productive conversation about something that will happen after the singularity. It would be rather like trying to argue about what will happen after the second coming. "Will pi still be transcendental?" "No, no, Jesus/the nanites will make circles slightly different than they are, so that it comes out even." What can you say?
daniel_the_smith wrote:So you think I might wake up in a society that can raise the dead but doesn't know how to fix poor memory? Which is the harder problem? This whole line of thinking makes no sense to me.
Well, we're talking about a number of different things here. One is freezing, unthawing, and repairing healthy brains, and then installing them in new bodies. Another is freezing, unthawing, and repairing whole bodies (healthy, unhealthy, in hospice). These both seem highly improbable to me (and also, separately, not hugely desirable), but the idea that we will freeze, unthaw, and repair *dead* bodies.... death is not kind to our bodies, and especially not to our brains. If you are imagining that we will be reviving people who died and were frozen the next day, you're imagining something so implausible that you might as well imagine anything else you want. But in that case, why not imagine that beneficient time-travelling aliens will scan our brains at the point of death and reincarnate us in the far future? I find that scenario
even more awesome.
But yes, I think that it's probably far easier to freeze, unthaw, repair, and reinstall a brain than to, as you so blithely put it, "fix poor memory".
daniel_the_smith wrote:jts wrote:... Two bodies could share a brain and not have any of the same memories ...
What? How? How can you share a brain and not share any memories? That's like saying you share a heart but not ventricles...
I'm asking you what you would think about a body which has the same brain in its cranium for, say, five thousand years. Imagine that society hasn't gotten around to fixing poor memory yet. (The nanites are forgetful.) The persons associated with these bodies and brains each have a set of memories, and there is no intersection between their memories. They share a brain, but no memories. (If there's any cardiac analogy, I'd say it's like saying "they share a heart, but no blood".)
daniel_the_smith wrote:I think, if I can sum up a bit: people change throughout their life; a 90 year old is not the same as his or her 10 year old self. We're OK with that kind of change, I think pretty much everyone is. There is a very real sense in which they are not the same person. If I wake up at time T, then at time T + 80 I will be a "different person" in that same sense, and I'm OK with that. It's a natural part of growth.
For you to make a personal identity argument against cryonics, you have to argue that between being frozen and reanimated, something will have changed that makes me not be me. I think that's been part of your argument, but you also seem to be implying that if I grow and develop after a reanimation, I'll no longer be me. I think that's true, but only in that same sense, and that I and most people are OK with that sort of incremental change. Even if we aren't, it happens to us every day.
There are two separate points at which you might need to consider that your identity has changed. One is that, due to problems with (or features of!

) resurrection, or the new environment in which you find yourself, or something else entirely, your newly resurrected identity is (or very quickly becomes) different from your old identity. The other is that, after some period of time, your most recent identity becomes different from your newly resurrected identity.
I'm asking you (and any other cryo-sympathizers, or anyone for that matter)
how big the difference would have to be, at either of those points, for you to no longer think that the resurrected person was you.
So far you've given two responses: one is that it's actually impossible for the person not to be you if technology is sufficiently advanced for reanimation to work (which does not answer the question), and the other is that you would consider
any person to be you, so long as the change took place sufficiently slowly (although you haven't said how slowly...).
Your concept of identity leads to some interesting possibilities, by the way. For example, imagine the time-travelling aliens scan your brain, but they badly screw up the first copy when they reanimate you (in fact, by a bizarre coincidence, he's exactly like Joaz). No problem, though, they just make another copy of you, and this one is perfect, electron for electron. However, over a period of thousands of years, the failed copy (the one that started out as Joaz) ends up becoming exactly like you in any aspect you choose to stipulate, while the one that started out as a perfect copy of you ends up becoming an incomprehensible, barely human entity that shares nothing with you at all. Then, when the aliens decided to take both copies of you back into the past to visit you (a family reunion of sorts). The one who is exactly like you is Joaz, you say, and the strange betentacled being is Daniel?