First, there's no way you could offend me by anything you say. You've already done me a great service by explaining your views. I've met people with similar views before, but usually they're reluctant to describe them at length.

I agree that traces of people remain after their death -- genetically, in their children, and in the memories of those who knew them. But those traces fade quickly, and for all but the most famous, virtually disappear in a few centuries. And surely you agree that a memory is a poor substitute for a person -- I'd rather be able to talk to my dad or neighbor than have even the fondest memories of them.

We both seem to agree that improving the quality of people's lives, as well as the quantity, is extremely important. Aging is far from the only problem society faces. Tackling inequality/poverty, political dysfunction, war, ignorance, and other problems are also extremely important goals, and I greatly respect people who work on them. I also recognize that curing aging will introduce new societal problems even as it solves others (e.g., rising health care costs).

I think where we differ is that I think these other problems can be solved as well, and I believe that curing aging will, on balance help society more than it harms it. Consider how our scientific progress is retarded when our best scientists die or lose their mental acuity later in life. I've already alluded to the fact that people seem to ignore problems ranging from global warming to the national debt because "I'll be dead before it becomes a problem."

I have several responses to your concern that if people stop aging, we won't have room for future generations. First, it is well known that wealthier people and countries have a lower birth rate, so by solving poverty, the birth rate will decrease. Second, even if people don't age, they can still die from accidents or disease. Also, I think eventually humanity will expand to the stars, although we are far from it now.

Massive societal change is coming, from many sources, whether or not aging is solved (although I make no claims about when). Technology is going to put many people out of work. AI will eventually be created. Methods will be developed to improve human intelligence, enhancing technological development but increasing wealth inequality. Even if none of these developments occur, there is still an increasing centralization of wealth and power in developed countries.

It is hard to know how curing aging would interact with these trends, except to say that I think people would be more circumspect about societal decisions if they knew they would have to bear the long-term consequences. I think the demand for religion would decrease, which would have positive effects on geopolitical stability. Living longer would also give people more time to get educated, which would help with the electoral ignorance that is at the root of so many problems in the US.

Finally, your proposed principle for determining the "correct" lifespan is not a new one:

> When you start to try and reverse or disable aging as opposed to attempting to cure disease.

The NIH takes a similar view. The problem is that almost all major diseases (diabetes, heart disease, neurodegenerative disease, to some extent cancer) are all diseases of aging. Young people don't (usually) get them. It may well be that to "cure" these diseases, we will have to solve the underlying problem -- that is, aging.

Also, consider that it is just genetic happenstance that our species max lifespan happens to be 120. Why should it not be 15 or 60 or 240? Letting evolution decide our lifespan is certainly the simplest method, but it seems fairly arbitrary.