It is certainly getting better.
Additionally, it is also important to figure it out that whether a common man in america has access to all those advancements and developments in medical science. If only rich and influential citizens avail the fruit of medical technology, then the claim made by author remains unsubstantiated and open to debates.
Then how come the average is already above 80?
Perhaps, it could also be possible that despite significant advancement in medical technology, life expectancy increased by just 1-2 years in last century. If this
were the case, then it's certainly next to impossible that within a few decades it will increase by over 10 years.
Yes, but this assumption is unreasonable. If it says "each generation lived longer than the previous one", then we expect the difference to be statistically significant; perhaps a few years. There were several generations in a century, so it cannot be just 1-2 years.
Third, the author concludes that 'most' children, born in next decade, will live past the age of ninety. Even if we assume that the trend will continue in future, it's not at all clear that today what is the proportion of people who live past 80 years. It could be possible that because a few people live past 125 years, the average life expectancy is above 80.
It is also possible that many people live until 81-89. However, if the average is so high as 80, it is not so unreasonable to assume that a lot of people should live until their nineties... though perhaps not "most".
I would also focus on the question of medical technology vs. other causes. Alternatively, you can also argue that the life expectancy probably cannot increase indefinitely.
it's not at all clear that today what is the proportion of people who live past 80 years
This sounds awkward.
Sergey Orshanskiy, Ph.D.
I tutor in NYC: http://www.wyzant.com/Tutors/NY/New-Yor ... ref=1RKFOZ