I could never have learned to ride a bike without my parents spending hours and hours trying to teach me.

Maybe there's a cultural difference, but I don't know what country you're in (or were in). I've never heard of anyone learning to ride a bike except by riding it. But clearly we need some evidence. I don't care for the bodge of using karma to conduct a poll, so I'll just ask anyone reading this who can ride a bicycle to post a reply to this comment saying how they learned, and in what country. "Taught" should mean active instruction, something more than just someone being around to provide comfort for scrapes and to keep children out of traffic until they're ready.

Results so far:

RichardKennaway: self-taught as adult, late 70's, UK

Morendil: taught in childhood by grandfather, UK?

Blueberry: taught in childhood by parents, where?

So that's two to one against my current view, but those replies may be biased: other self-taught people will not have had as strong a reason to post agreement.

That car sure looks old! That correlates with low income, and lower intelligence

Insufficient data, though perhaps a reasonable heuristic. Many people do this, despite being able to afford a more expensive car. Why? Driving an older model high-end car is a good way to avoid the attention of thieves, while retaining a lot of utility. My 14 year old Mercedes has a feature set comparable to a recent model Corolla, but thieves will pay more attention to the Corolla. A car is also a bad place to put one's money. It's much better to buy a cheaper car and invest the difference.

Do you stop enjoying sex when you use birth control?

I stop enjoying sex when the other person isn't really aroused. The mechanisms for detecting affect evolved before language and abstract cognition. There is good reason to believe that it takes a whole lot of effort to alter or falsify them. These mechanisms are tools, we are stuck with them, so it behooves us to use them optimally. I think trying to like someone is suboptimal.

Someone trying to like me is like a rapid-onset smile. Someone who simply likes me is like a slow-onset smile.

Instead of trying to like things because it's instrumentally useful, I think it's far better to strive for optimal instrumentality from one's liking.

The former would be like learning about a genre of music because it's popular. The latter is like delving into a genre of music because one finds it moving. Great things come out of the latter. Mediocrity comes out of the former.

(Underlying this debate is the erroneous notion of the "blank slate." Our emotions are not a blank slate. They are a finely tuned processing and guidance mechanism, just not tuned for our present circumstances.)

to hope really to defeat death is a delusional escape from the mature acceptance of death

Let's rephrase this with the troublesome terms unpacked as per the points you "largely agree" with: "to hope for a life measured in millenia is a delusional escape from the mature acceptance of a hundred-year lifespan".

In a nutshell: no! Hoping to see a hundred was not, in retrospect, a delusional escape from the mature acceptance of dying at fourty-something which was the lot of prehistoric humans. We don't know yet what changes in technology are going to make the next "normal" lifespan, but we know more about it than our ancestors did.

it strikes me as irrational as a way to deal with death itself

I can believe that it strikes you as weird, and I understand why it could be so. A claim that some argument is irrational is a stronger and less subjective claim. You need to substantiate it.

Your newly introduced arguments are: a) if you don't die you will be transformed beyond any current sense of identity, and b) "the only possible perfect state is non-existence". The latter I won't even claim to understand - given that you choose to continue this discussion rather than go jump off a tall building I can only assume your life isn't a quest for a "perfect state" in that sense.

As to the former, I don't really believe it. I'm reasonably certain I could live for millenia and still choose, for reasons that belong only to me, to hold on to some memories from (say) the year 2000 or so. Those memories are mine, no one else on this planet has them, and I have no reason to suppose that someone else would choose to falsely believe the memories are theirs.

I view identity as being, to a rough approximation, memories and plans. Someone who has (some of) my memories and shares (some of) my current plans, including plans for a long and fun-filled life, is someone I'd identify as "me" in a straightforward sense, roughly the same sense that I expect I'll be the same person in a year's time, or the same sense that makes it reasonable for me to consider plans for my retirement.

It's certainly best to accept that death is inevitable if you know for a fact that death is inevitable. Which emotion should accompany that acceptance (calm, depression, etc.) depends on particular facts about death - and perhaps some subjective evaluation.

However, the premise seems very much open to question. Death is not "inevitable", it strikes me as something very much evitable, that is which "can be avoided". People used to die when their teeth went bad: dental care has provided ways to avoid that kind of death. People used to die when they suffered infarctus, the consequences of which were by and large unavoidable. Fibrillators are a way to avoid that. And so on.

Historically, every person who ever lived has died before reaching two hundred years of age; but that provides no rational grounds for assuming a zero probability that a person can enjoy a lifespan vastly exceeding that number.

Is it "inevitable" that my life shall be confined to a historical lifespan? Not (by definition) if there is a way to avoid it. Is there a way to avoid it? Given certain reasonable assumptions as to what consciousness and personal identity consist of, there could well be. I am not primarily the cells in my body, I am still me if these cells die and get replaced by functional equivalents. I suspect that I am not even primarily my brain, i.e. that I would still be me if the abstract computation that my brain implements were reproduced on some other substrate.

This insight - "I am a substrate independent computation" - builds on relatively recent scientific discoveries, so it's not surprising it is at odds with historical culture. But it certainly seems to undermine the old saw "death comes to all".

Is it rational to feel hopeful once one has assigned substantial probability to this insight being correct? Yes.

The corollary of this insight is that death, by which I mean information theoretical death (which historically has always followed physical death) holds no particular horrors. It is nothing more and nothing less than the termination of the abstract computation I identify with "being me". I am much more afraid of pain that I am of death, and I view my own death now with something approaching equanimity.

So it seems to me that you're setting up a false opposition here. One can live in calm acceptance of what death entails yet fervently (and rationally) hope for much longer and better life.

I give up for now, and suggest reading the sequences, maybe in particular the guide to words and map-territory.

You can think about a world that doesn't contain any minds, and yours in particular. The property of a world to not contain your mind does not say "nothing exists in this world", it says "your mind doesn't exist in this world". Quite different concepts.

That said the phrase "the situation of yourself dying" strikes me as an emotional ploy.

This wasn't my intention. You can substitute that phrase with, say, "Consider the subjective point of view of yourself-now, on the situation of yourself being dead for a long time, or someone else being dead for a long time for that matter." The salient part was supposed to be the point of view, not what you look at from it.

1) Who said anything about morality? I'm asking for a defense of the essential rationality of cryogenics.

See What Do We Mean By "Rationality"?. When you ask about a decision, its rationality is defined by how well it allows to achieve your goals, and "moral value" refers to the way your goals evaluate specific options, with the options of higher "moral value" being the same as options preferred according to your goals.

2) Please read the whole paragraph and try to understand subjective point of view - or lack thereof post-death.

Consider the subjective point of view of yourself-now, on the situation of yourself dying, or someone else dying for that matter, not the point of view of yourself-in-the-future or subjective point of view of someone-else. It's you-now that needs to make the decision, and rationality of whose decisions we discuss.

I suppose I'd see your point if I believed that drug addiction was inevitable and knew that everyone in the history of everything had eventually become a drug addict.

Whether something is inevitable is not an argument about its moral value. Have you read the reversal test reference?

After death there IS no time - past present or future.

Please believe in physics.