Paperwork
Other people have done it. You fill in blanks. It just seems too high.
Some law is passed that prohibits cryonics (before you're even dead)
It would be difficult to block someone with such a law because one could always be transported. Will Federal laws be passed in the US, and Canada? Probably not. US, Canada, and Anguilla? No chance.
Not all of what makes you you is encoded in the physical state of the brain
What are the other options? Sure, if I had a wound to my stomach I might "feel anxiety" differently, or something.
All people die (nuclear war? comet strike? nanotech?)
Nuclear war would not kill everyone. Comet strike defenses are getting better and the risk is low. Nanotech...factory produced things will be more efficient than self-replicators, I do not expect self-replicators to be where investment is put. It is easier to break things than fix them, self replicators are breaking things not too hard to break, as they are practically alive.
Humans with no technology survived the ice age. Someone's surviving whatever we do in a bomb shelter with a million cans of tuna, or on Tasmania, or something.
The technology is never developed to extract the information
Take thin slices, print it. Conceptually it's not hard, even if technologically impossible. It doesn't seem outlandish or as a thing in kind that must be invented, like nanotechnology is.
It is too expensive to extract my brain's information
Things get cheap.
Running people in simulation is outlawed
Weirdly specific, but you could be revived as well.
It is too expensive to run me in simulation (if we get this far I expect cheap powerful computers)
Just go slower, and run on a Pentium III at one second per decade or whatever.
Far too low:
You die suddenly or in a circumstance where you would not be able to be frozen in time (see leading causes of death)
I didn't look at actuarial tables, but head trauma is not a good thing, more than time is involved.
Society falls apart (remember this is the chance that society will fall apart given that we did not see "all people die")
Much probability mass taken from "All people die" (you had it at .3, I have it about .01), but still more than your .2+.3. More like .8. Societies fail. They just do. That's what they do. If the society isn't basically stable, it will change until it eventually dies. The society will have institutions poorly designed for past circumstances (as overreactions to even older circumstances) persist and be less and less appropriate. The society will consume resources until they are gone. The society will have cooperative morals decay and become a mass of individuals. Societies...for these things death is natural more than it is for humans.
Societies fail. They just do. That's what they do.
Not anymore. Societies fall, but they fall a fixed distance before they restructure and recover, and they start a little higher every year.
If an American signs up for cryonics and pays their ~$300/year, what are their odds of being revived? Talking to people at LessWrong meetups I've heard estimates of 1 in 2. My friend George Dahl, whose opinion I respect a lot, guesses "less than 1 in 10^6". Niether has given me reasons, those numbers are opaque. My estimate of these odds pretty much determines whether I should sign up. I could afford $300/year, and I would if I thought the odds were 1:2, but not if they were 1:10^6. [1]
In order to see how likely this is to work, we should look at the process. I would sign up with a cryonics company and for life insurance. I'd go on living, enjoying my life and the people around me, paying my annual fees, until some point when I died. After death they would drain my blood, replace it with something that doesn't rupture cell walls when it freezes, freeze me in liquid nitrogen, and leave me there for a long time. At some point, probably after the development of nanotechnology, people would revive me, probably as a computer program.
There's a lot of steps there, and it's easy to see ways they could go wrong. [3] Let's consider some cases and try to get probabilities [4]:
Update: the probabilities below are out of date, and only useful for understanding the comments. I've made a spreadsheet listing both my updated probabilities and those for as many other people as I can find: https://docs.google.com/spreadsheet/...
Combined Probability Of Failure: 99.82%
Odds of success: 1 in 567.
If you can think of other ways cryonics might fail, moving probability mass from "other" to something more quantifiable, that would be helpful. If you think my numbers are off for something, please let me know what a better number would be and why. This is not final.
Am I going about this right? Do people here who think it's rational to sign up for cryonics take a "the payoff is really high, so the small probability doesn't matter" view? Am I overly pessimistic about its chances of success?
Note: I originally posted this on my blog, and the version there has a silly javascript calculator for playing with the probabilities.
[1] To figure out what odds I would accept, I think the right approach is to treat this as if I were considering signing up for something certain and see how much I would pay, then see what odds bring this below $300/year. Even at 1:2 odds this is less effective than Village Reach at averting death [2], so this needs to come out of my 'money spent on me' budget. I think $10,000/year is about the most I'd be willing to spend. It's a lot, but not dying would be pretty nice. This means I'd need odds of 1:33 to sign up.
[2] Counter argument: you should care about quality adjusted life years and not deaths averted. Someone revived maybe should expect to have millenia of life at very high quality. This seems less likely to me than just the claim "will be revived". A lot less likely.
[3] In order to deal with independence issues, all my probability guesses are conditional on everything above them not happening. Each of these things must go right, so this works. For example, society collapsing and my cryonics organization going out of business are very much not independent. So the probability assigned to the latter is the chance that society won't collapse, but my organization goes out of business anyway. This means I can just multiply up the subelements to get probabilities for sections, and then multiply up sections to get an overall probability.
[4] This has a lot in common with the Warren formula, which was inspired by the Drake equation. Robin Hanson also has a breakdown. I also found a breakdown on LessWrong that seems really optimistic.
EDIT 2011-09-26: jsalvatier suggested an online spreadsheet, which is very sensible. Created
EDIT 2011-09-27: I've updated my probabilities some, and made the updates on the spreadsheet.