It is certainly true that ideology and moral progress seems to be a generational phenomenon
This empirically seems to be difficult to confirm. Let's pick two major historical issues where attitudes are considered to have changed rapidly in the United States, attitudes towards interracial marriage and attitudes towards gay marriage.
I'm using Gallup as a rough estimate for historical interracial attitudes. In 1958, there was an approval rating of 4% for interracial marriage and a disapproval rate of around 94%. In 1969 that had changed to 20% and 73%. Now, the population was around 174 million in 1958 and 200 million in 1968. Using the estimated death rates from here, which gives about 2 million people dying yearly and assuming that about 2/3rds of all people who died were against interracial marriage and that about 2/3rds who were entering the population (for a year 10 year period, really not actual births but people who had been too young to earlier have an opinion or if have an opinion be asked about it in polls, but roughly the same as just new people), then one gets around 18 million people leaving the disapprove group and around 8 million entering, for a total delta of -10 million, which gives an expected value percentage of 164/200= .82%.
Of course, the most questionable number here is the 2/3rds. That seems like a safe estimate, but if one assumes a larger fraction then one gets other results. If one assumes that instead of 2/3rd it is nearly complete conversion (only disapproves dying and only approves entering the population) then one somewhat undershoots this. But at least from this sort of estimate it seems difficult to say that deaths were the only cause of the changing attitude. It does seem however that deaths were a major part.
Similarly, approval rates for gay marriage and civil unions have changed faster than a simple population die off model would work.(source) Here it is worth seeing how extreme the numbers are. There's been about a 10% decline between 2001 and 2011 in the fraction opposing gay marriage and about a 10% increase in the percentage who are ok with it. There are around 2.5 million deaths a year in the US in the last decade, meaning that about 25 million people died. (source) There were in 2001 a population of around 281 million, so with a 57% disapproval of gay marriage that translates to around 160 million people. So if all 25 million died off from that population then one gets around 135 million disapproving which out of 308 million population is around 44% disapproval, which is about the current rate. Now, it might look from that like die off is the only cause here, but this model assumes that almost everyone dying is in the disapprove category and that almost no new people are entering into that category. The second assumption is at least empirically wrong. From those numbers one sees that young people are much more likely to approve, but it isn't enough to justify this sort of assumption.
So the data seems to suggest that death is a major cause of moral changes but at least for both these issues, a major part is people actually changing their minds. Now, it is possible that they are changing their minds in part because the older authority figures are dying off, but that's a more subtle narrative.
Overall, crunching these numbers has made me update more in the direction of deaths mattering. When I started pulling up the numbers I expected it to be much more clear cut in the direction of deaths not being sufficient. This seems to suggest that they aren't sufficient, but it does seem like in reasonably simple. plausible models deaths do explain a large fraction and possibly majority of the change.
Getting more detailed understandings might require much more careful demographic study.
Similarly, approval rates for gay marriage and civil unions have changed faster than a simple population die off model would work
I have noticed in the past that the majority of people allow their opinions to be swayed by a minority of individuals. So I suspect that 'die off rates' might be magnified in this manner -- but I can't really corroborate that. It's worth investigating at some point, especially if I'm going to raise it as an issue.
With apologies to Ed Regis.
Modern science has caused humankind to develop better cures and patches for once-debilitating conditions; people often survive maladies which would have killed them not long ago. In the wake of this and of a recently changing attitude regarding how cognitively disabled people might see the world, a disability rights movement came into swing in the 1970s. Increasingly, the attitude of disabled people was that it wasn't inherently bad to be disabled; a disability could be an intrinsic part of a person's self-image. Some people in wheelchairs, for instance, want badly to be able to walk - but some do not, and the mainstream attitude has historically not validated those people's experiences. This is where disability culture intersects the transhumanist movement. If it is possible to identify so strongly with a physical disability as to not want any cure, how does that mesh with believing that it is desirable to improve one's mind and body? Is it possible to identify as a happily disabled transhumanist?
This does not intend to suggest that transhumanism is a movement of eugenic warriors; it's hard to imagine anyone suggesting that folks who don't sign up for the "Harmless and easy cure for senescence" shot be sterilized. However, despite the fact that hardly anyone would identify emself as an eugenicist (a fine thing to call yourself once-upon-a-time in America, until the Nazis rendered the term unpopular,) literally eugenic attitudes in society prevail, e.g. the prevalent belief that people with Huntington's disease or schizophrenia who reproduce are cruel for hazarding the inheritance of their condition.
One wonders what disability culture would look like if people who are today in wheelchairs had access to technology that could repair their legs and allow them to walk. I wonder if people with congenital disabilities which would today require a wheelchair would have a choice about being cured, or whether the cure would be implemented in infancy. In 2007, a girl named Ashley who has an unknown brain disorder and cannot communicate or move herself effectively was given a series of radical procedures - hysterectomy, mastectomy and high estrogen doses - intended to make her easier to take care of. Was the literally non-consensual hysterectomy an eugenicist procedure? An immoral one? Was it in the spirit of transhumanism? In a future where Down syndrome can be prevented with a prenatal vaccine, would such a vaccine be moral? How about vaccines for "low-functioning" autism? At that rate, surely it would be possible to vaccinate for Asperger syndrome, depression, and ADHD, conditions which many people dislike and/or dislike having. (As an aside, with all the medically-repudiated yet widespread fear about vaccines causing autism, one can only imagine the panic an autism vaccine would cause.)
I don't have answers to these questions. I have feelings and impressions, but those are not very useful. The issue cannot be solved unilaterally by saying that only those who enthusiastically consent to certain medical procedures should be given them, because many people are incapable of giving clear consent, as in the Ashley treatment. Nor can it be clearly solved by suggesting only prophylactic measures against disabling conditions, because certainly some parents would forego those measures. In a transhuman future, is the birth of a nonverbal autistic a preventable tragedy? Is it less of a tragedy if the child is a savant? Nor can one say that only conditions without an accompanying culture should be eradicated. Even if the definition of 'culture' were not elusive, HIV/AIDS has a definite culture about it, and few people would suggest that HIV should not be eradicated.
It is not useful to ignore the role of disabled people and disability culture in the transhumanist movement. I believe that the future has a lot to offer many people with disabilities, including those who do not want a 'cure.' Transhumanism can encompass interest in diverse AAC methods, and I believe it should. Simple keyboard technology has made it possible for many otherwise nonverbal people to communicate eloquently, as have DynaVox devices and various iPad apps. It would delight me to see widespread discussion about more powerful AAC devices, which could enable us to perceive and act on the desires of those who cannot now communicate.
Nor has technology reached its limits in helping those with physical disabilities; wheelchairs are generally clumsy and heavy, and expensive for people without insurance - nearly inaccessible to people who live without insurance in impoverished areas of the world (or of the United States.) People who, like Stephen Hawking, become paralyzed by motor neuron diseases, do not all possess Stephen Hawking's access to high-tech communications devices (for which prices begin at thousands of dollars.) And people with disabilities like epilepsy or cerebral palsy are still often abused for their "demonic possession" or inaccurately stereotyped as mentally disabled. The transhumanist movement tends to advocate augmentation sans cure as far as physical disabilities are concerned, but there are people with mixed feelings about transhumanism as it applies to disability.
Disability is a hot button topic surrounded by widely varying spectra of beliefs. It directly affects humankind and is not often discussed rationally because of the subjective experiences people have had with varying disabilities. (The mother of a nonverbal autistic says, "There should be a cure for autism; I want my son to say he loves me." A nonverbal autistic communicating by AAC says "There shouldn't be a cure for autism; I want people to learn how I communicate my affection." Their conflicting beliefs do not predict radically different anticipated experiences.) So a rational, clear dialogue about disability is vital - for disabled people, their friends and families, and the world at large - in order to integrate these identities and experiences into the future and present of humankind.