You don't have to believe me. I'm only relaying what is the currently accepted scientific understanding, that so far we've only treated the symptoms of aging, not increased the potential for longevity.
"The U.S. Census Bureau view on the future of longevity is that life expectancy in the United States will be in the mid-80s by 2050 (up from 77.85 in 2006) and will top out eventually in the low 90s, barring major scientific advances that can change the rate of human aging itself, as opposed to merely treating the effects of aging as is done today." (emphasis mine)
> surely you're not suggesting that longevity decreased on average between 1920-2000?
You've completely lost me here. This is a straw man argument, I didn't say a thing about what happened to longevity this century, and the data clearly shows it has gone up slightly. Experts agree it will reach an asymptotic peak unless some science magic happens. But no science magic has yet happened, and while I agree we should pursue it, we have no scientific reasons to suspect that it will aside from human curiosity, desire to live longer, and fear of death.
> Kurzweil is overly optimistic about these things
Now that's just funny. There's a world of difference between being optimistic and overtly lying to prove a point that doesn't exist.
Again, The Census Bureau is hardly an authority on this matter - they're concerned with the challenge of just logistically counting Americans every few years via surveys (the lowest order of the scientific method) and it's questionable how precisely they even do that considering I can attest to having missed one such survey myself years ago. I treat their predictions on longevity with the same skepticism I view their census stats, which is optimistic given the massive gap in expertise. This, by the way, is in no way an attempt to diminish the very real and difficult challenges this task presents - only to place their expertise accurately.
Experts very much DO NOT agree on this and the fact that literally billions of dollars in R&D are expended on this area of science in just the US is testament to that. Sure it doesn't mean any groundbreaking discovery is guaranteed to happen - but it does show that belief in the possibility is alive and well. And why not? Those immortal jellyfish share 97% of the same DNA, including long stretches of matching sequences and compatible genes that have been experimentally transferred between them and other life forms numerous times. Even Right Whales, which are conscious mammals sharing immense biological relation to people can live 200 years or more, and that's in the absence of anything remotely resembling science and the presence of numerous impediments, including us, their generic brethren. Tardigrades may end up being miniature space suits for the most advanced intergalactic life forms known - who knows? What we do know is they throw most of what we believed to be true about life and morality right out the window - and that's a good thing. All this is to say that the possibility of longetivity increases driven by scientific exploration is much greater than the likelihood of that not being the case.
Kurzweil is who he is, for better or worse. But he has made outlandish predictions over the years, many of which have come about despite the skepticism. He's a successful entrepreneur and employed in a very senior position at one of the most valuable and forward looking companies in the world. He's not everyone's cup of tea, but I don't completely dismiss him as a crank. I disagree with some of the time lines he has, though cautiously because it doesn't take many compounding discoveries to get there on his schedule. But fundamentally, I agree with much of what he says - even though I think what they mean for us as humans and the universe as a whole is much less certain, and likely as scary as they are promising.
EDIT: here are some links you might want to read to confirm that whole "experts agree" conclusion:
Henrietta Lacks - the woman whose specific cancer mutation provided the vast majority of cells used to study cancer and numerous other cellular process, to this day. Cells which are effectively immortal: http://www.todayifoundout.com/index.php/2010/05/there-was-on...
"The U.S. Census Bureau view on the future of longevity is that life expectancy in the United States will be in the mid-80s by 2050 (up from 77.85 in 2006) and will top out eventually in the low 90s, barring major scientific advances that can change the rate of human aging itself, as opposed to merely treating the effects of aging as is done today." (emphasis mine)
https://en.wikipedia.org/wiki/Longevity
> surely you're not suggesting that longevity decreased on average between 1920-2000?
You've completely lost me here. This is a straw man argument, I didn't say a thing about what happened to longevity this century, and the data clearly shows it has gone up slightly. Experts agree it will reach an asymptotic peak unless some science magic happens. But no science magic has yet happened, and while I agree we should pursue it, we have no scientific reasons to suspect that it will aside from human curiosity, desire to live longer, and fear of death.
> Kurzweil is overly optimistic about these things
Now that's just funny. There's a world of difference between being optimistic and overtly lying to prove a point that doesn't exist.