Should we want to live longer?

I've been lecturing about various genetic enhancement strategies in my genetics course the last two weeks. Today's lecture concerned clinical trials for gene therapy, but I have also talked about cloning, pharmacogenomics, genetic testing, GMO's and other aspects of biotechnology.

I ask my students to explore and engage with moral and ethical arguments. For example, we discussed whether there could be changes that would objectively be improvements in human biology. If so, are there moral or ethical objections that might apply to them? I don't think students are often asked to think in these ways, certainly not in basic science courses, so I am always interested to see where the conversation will go.

One of the topics last week was life extension. I can make a reasonable case that living longer (say, an average increase of 10 years) would be an objective improvement in human biology. The opposite case, dying 10 years earlier, seems like it would be an objective detriment.

I won't elaborate on my students' conversation along these lines -- that being limited to class -- but I wanted to give the story as a prologue, before linking to this op/ed by bioethicist Arthur Caplan, on the topic of life extension.

In this case Caplan does a good job expressing common sense (something not always true of Caplan's writing):

That said, arguments that we should not live a lot longer because we will grow decrepit are simply silly. No one proposes that we spend a lot of money on biomedical research to pursue a longer life of decrepitude and suffering. The idea behind radical life extension is that we live a decent quality of life for a lot longer. If all that is in store is frailty and mental decline, then the debate is over before it starts. But that is not what the debate is really about.
As for violating some natural limit if we live a lot longer -- what limit? We have already doubled our lifespan since the days of the Hittites, Israelites, Greeks, Babylonians and Egyptians, all of whom were lucky to make it to 35. Are we already living unnatural, and thus immoral, lifespans?

He also argues that it is not vain or indulgent to want to live longer, because others may wish you could live longer (children, grandchildren) even more than yourself. Those are good arguments, and it is hard to come up with a coherent argument against the idea that people should extending their lives if they want to do so (again, assuming that there is no unacceptable trade-off of increased pain and suffering).

UPDATE (2008/04/30): Arthur Caplan writes:

I would demur from the view expressed on your blog. I think all Caplan's writings are eminently sensible.

Heh. I think I've been just been served...