I can’t point you to anything better than what is posted at Alcor’s and CI’s sites, no. Instead let’s look at what you say below. Sure there is an objective, impersonal truth of the matter about the current state of any particular technology. The question is whether what we do with that truth should be similarly objective and impersonal, and I don’t think it should. I believe it is OK for people to have different values and priorities, whether it’s concerning the merits of tomato ketchup or the value of life. Therefore, I believe there is a range of legitimate opinions about the justifiability of a given course of action. For sure that range will be finite, i.e. there will be cases where people are not adopting a policy that is consistent with their other beliefs and will be resistant to recognising that fact, but that doesn’t change that fact that there is still that (finite) room for legitimate agreement to disagree. Cryonics is a rather extreme case, because its basis in the prospect of revival in the rather distant future entails so much uncertainty as to the pros and cons. I value my and others’ lives very highly, and I consider it quite likely that the future will be a progressively more fulfilling place to be, so I think signing up for cryopreservation makes sense even if one evaluates the chance of being revived and being glad one had been is quite low (I would probably go as low as 1%, and I definitely think we’re up at at least 10% today, even taking into account the issues we’ve been discussing). But I don’t claim to have an objective, impersonal argument for that 1% - rather, if someone else values life less than I do and/or they are more pessimistic about human progress, and they conclude that their cutoff is 50%, they’re welcome to their opinion. No?I agree about some scope for people to differ, though I don't think the reasonable range extends to not signing up for cryonics that is 50% likely to work, for people who can afford it.
I, too, value life very highly and expect the future to be dramatically better. I think concerns about e.g. overpopulation and running out of jobs are bad philosophy, both generally (problems are soluble, and we don't have to and shouldn't expect to know all future solutions today) and also I could give specific arguments on those two issues today. And I'm not worried that I might not be glad to be revived.
But we have a disagreement about methodology and epistemology, which comes up with your comments on percentages.
If I believed cryonics had even 1% odds in a meaningful sense, I'd sign up too. I value my life more than 100x the price. That's easy. An example of meaningful odds would be that for every 1000 people who sign up, 10 will be revived. But it doesn't work that way.
Explanations don't have percentage odds. It's important to look at issues in terms of good and bad explanations, and criticisms, not odds. (You may have some familiarity with this view from David Deutsch, including his criticisms of weighing ideas and of Bayesian epistemology.)
In FoR, DD uses the example idea that eating grass will cure a cold. Because there's no explanation of how grass does that, he explains that this empirically-scientifically testable idea isn't worth testing. It should be rejected just from the philosophical criticism that it lacks a good explanation.
It shouldn't be assigned a probability either. It's bad thinking, to be rejected as such, unless and until a new idea changes things.
Odds apply to issues like physical events. Odds are a reasonable way to think about the possibility of dying in a plane crash, or other cryo-incompatible deaths. Odds can even somewhat model problems like whether the cryo staff will make a mistake, or whether Alcor stays in business, though there are some problems there.
You could die in a plane crash, or not. It could go either way, so odds make some sense. But either current cryo methods (assume perfusion etc go well) preserve the necessary information, or they don't. That can't go either way, there's a fact of reality one way or the other.
The basic way odds are misused is there are multiple rival ideas, and rationally resolving the conflicts between them turns out to be difficult. So people seek ways to retreat from critical discussion and find a shortcut to a conclusion. E.g. a person favors an idea, and there is some idea which contradicts it which he can't objectively refute. Rather than say "I don't know", or figure out how to know, he assigns some odds to his idea, then lowers the odds for each criticism he doesn't refute. But the odds are completely arbitrary numbers and have no bearing on which ideas are correct.
Fundamentally, he's mistaken to take sides when two ideas contradict and he can't refute either one. Often this is done by bias, e.g. favoring the idea he thought of himself, or spent the last five years working on.
A starting point for a cryo explanation is that digging up graves to revive people won't work, due to brain damage (this could be explained in more detail I won't go into). There is no good explanation of how it could ever work. This bad explanation isn't worth scientific testing, and should not be assigned any odds.
Freezing people is better than coffins because it preserves more brain matter and prevents a lot of decay, but there's no good explanation that it would work either, because there's so much brain damage. All claims that it would work can be refuted by criticism (in the context of present knowledge). But vice versa doesn't apply: one could write an explanation of why straight freezing won't work for cryo, which would stand up to criticism. (Today. All these things are always tentative, and can be rethought if someone has a new idea.)
That is how issues should be resolved rationally. Get a situation with one explanation that survives criticism, and no rivals that do. Then, while one could still be mistaken, there is a non-arbitrary opportunity to accept the best current knowledge.
This is a Popperian view, which many people disagree with. They're wrong. And all of their arguments have known answers. I can answer any points you're interested in.
Changing subjects briefly, let's apply this to SENS. SENS is the best available knowledge on the issues it addresses, and which should not be dismissed by arbitrarily assigning it odds. Odds are a semi-OK approximation for whether specific already-understood SENS milestones will be done by a particular date, but are not an OK way to judge the truth of the core explanatory ideas of SENS. It's very important to look at SENS in terms of the proposed explanations and criticisms, and actually resolve the conflicts between different ideas (e.g. go through the criticisms of SENS and figure out concretely why each criticism is wrong, rather than be unable to objectively and persuasively answer some criticism but continue anyway. Note you are able to address EVERY criticism, which makes SENS good, as opposed to other ideas which don't live up to that important standard.)
Finally, today's vitrification processes cause less brain damage than freezing. But still lots of brain damage. So for the same main reason as before (lots of brain damage prevents reviving), cryonics won't work (until there's better technology).
Either this is the best available explanation, or there is information somewhere refuting it, or there is a rival for the best explanation that's also unrefuted. In each case, it's not a matter of odds, and this initial skeptical explanation regarding cryo I've given should stand as the best view on the matter unless there are certain kinds of specific relevant ideas (rivals, criticisms).
Behinds statements about odds, there usually are some explanations, but it'd be better to critically discuss them directly.
I'm guessing you may have in mind an explanation something like, "We don't know how much brain damage is too much, and can model this uncertainty with odds." But someone could say the same thing to defend straight freezing or coffins, as methods for later revival, so that can't be a good argument by itself.
To make a rational case for today's cryonics, there has to be some explanation about how much brain damage is too much, why that much, and how vitrification gets over the line (while, presumably, freezing and grave digging don't – though Alcor and CI don't seem to take that seriously, e.g. Alcor has dug up a corpse from a grave and stored it). Well, either there should be an explanation like I said above, or one explaining why that's the wrong way to look at it, and explaining something even better. Without good explanation, it's the grass cure for the cold again. You may also have in mind some further answers to these issues, but I can't guess them, and if they are good points that good content was omitted from the statement of odds.
Finally to put it another way: I don't think people should donate to SENS if the explanations in Ending Aging didn't exist (or equivalent prior material). Those good ideas make all the difference. Without those ideas, a claim that SENS might work (even with only 10% odds) would not suffice. And I don't think cryonics has the equivalent good explanations like SENS. (Though I'd be happy to be corrected if it does have that somewhere.)
If you are interested, I will write more explaining the philosophy here. Actually I did write more and deleted it, to keep things briefer. Epistemology, btw, is my chosen specialty. (I don't want any authority, I just think it's relevant to mention.)
Continue reading the next part of the discussion.