Saturday, February 25, 2006

Is longevity good for you?

Last Thursday's seminar was from Doug MacLean, on the topic of longevity. The question arises: is it better to live for longer? Doug controversially argued that (1) living longer is not generally better for a person; and (2) even if it is, it isn't better for society at large. The practical conclusion is that we shouldn't waste our resources on life-extension research. I strongly disagree with the first point, and am unsure about the second.

If I understood him correctly, MacLean's main argument for (1) rested on the premise that welfare isn't additive, and instead what matters is the shape of a life. (If you read the comments to the above link, you'll find Mike B. defending a similar position.) I couldn't discern much of an argument for those claims, however. Some thought experiments were mentioned which for me yield the opposite intuition.

For example, MacLean asked us to imagine an elderly couple who both lived very fulfilling lives, up until one of them died, and then the other lived a further six happy years. MacLean suggested that, in assessing the two lives, we wouldn't say the former life was worse. I disagree, and would confidently judge that the extra six years of happiness made the longer life better for the person living it. We might even speak of this comparative judgment, observing that, though both people lived outstanding lives, the one was "blessed with an extra six years" of happiness. (Of course, my theory of welfare has a simple way to determine the fact of the matter: just find out the idealized preference of the person in question. "Would you rather die now or live a further six years of happiness?" Seems to me that any sane person would choose the latter.)

Note also the asymmetry of regret, which I think counts against focusing exclusively on the 'shape of a life'. Suppose 'Bob' dies early and 'Sue' gets the extra six years. We might regret (for his sake) that Bob was not around to enjoy those final years of happiness with Sue. We surely would not regret the fact that Sue was still alive after Bob was gone. But MacLean's position seems to imply that this would be just as appropriate a response.

MacLean also appeals to the analogy of a short holiday. The idea is that if you can do everything appropriate for a good holiday in just two weeks, then there's really nothing to be said for staying a third week, even if you would continue to very much enjoy it. The overall experience would not be a better instance of its kind (i.e. "short holiday"). But again, I just have wildly different intuitions here. Happiness is a good thing (though not the only good thing), and - ceteris paribus - more of a good thing is better! Though welfare value isn't purely additive, since global preferences and the shape of a life do matter, I think addition is part of the story.

Then again, that might just be my personal preference. Subjectivism can account for inter-personal variation here. Perhaps it would be better for me to take the extra week's vacation (or live for longer), but not so for Doug, if he rationally lacks these preferences.

I'll discuss the second issue another day.

P.S. I sadly missed the Q&A session, so some of these concerns may have been answered then. (If anyone reading this was there, feel free to chime in!)


  1. The only argument against radical longevity carries any weight with me at all is the argument from attrition -- people tend to get stuck in their ways by the time they hit middle age and progress occurs in a large part because the last generation dies off and the new one with new ideas takes over. Having people around indefinitely might hamper that natural ideological mulching effect. Other than that, I say full steam ahead.

  2. I agree that it is counterintuitive to say that a longer happy life is not (all things considered) better than a shorter happy life. I think a more interesting question (particularly w/ regard to the longevity research question) is what sort of good extra life is, and how it should factor into our moral reasoning.

    I do think MacLean's short holiday does have some relevance given that (1) we never know whether a bit more time might spoil it, which is also true of life; and (2) it does show a way in which a person could reasonably not care (much) about whether they live a bit longer. In that sense a sane person wouldn't necessarily prefer a longer life (even if they wouldn't mind it). Everyone would be in a sort of gambling game for living the fullest life of happiness they can; and at some point it starts being reasonable to say, "Well, I've had a good life so far, so, just considering the longevity of it, it doesn't matter so much whether I continue to have it for just a year or two more," just as at some point it becomes reasonable to say, "This has been a great holiday; it might be nice to stay a few days more, but it isn't necessary."

  3. It occurred to me while at the store that there is a possible argument for the shape of one's life being the primary thing. When people evaluate the happiness of people's lives, they don't, in fact, generally rate length as very important -- length is sometimes considered, but the way people usually evaluate happiness is by peaks & ends: That vacation is happiest in which you have (at some point in the vacation) the best time and ends well, that life is happiest in which you have some great high peaks and a good end-of-life. That's where most people's intuitions seem to be. So, the argument might go, longevity is only icing on the cake, and shouldn't be a significant social priority at all.

  4. Here's a radical idea: how about we let people decide how long they'd like to live, and not interfere in their attempts to support the science that will lead to radical life extension?

    It's pretty odd to see blithe discussing a topic that has, lurking behind it, the fairly obvious implication that some people have no qualms about using government force to establish upper limits to life span. Replace "healthy life extension technologies" with "dialysis" or "heart medicine" and see how you feel about the same argument being made there.

  5. I don't see any such 'fairly obvious implication'; at least, it seems to me that the view of government you'd have to have to move from the questions discussed in Richard's post (Is it better to live longer? Should longevity research be a high priority in medical research?) to your 'fairly obvious implication' would be utterly irrational. The substitution is precisely what is at issue in the second question, namely, whether in terms of medical research priorities we should be putting longevity research on the same level as dialysis or heart medicine. (The real question is whether we should devote research resources to longevity, as such, that might be devoted to giving us better treatment for heart disease or the like.)

  6. Death by organ failure (eg old age) or death by heart attack or cancer or whatever are pretty hrd to seperate.
    If longevity reserch found a way to trick the body into thinking it was still young thenyou would solve a host of problems simultaniously. So I dont think you can see it as a simple trade off.
    As Reason implies I think that having the option open to survive longer is probably a good idea just likeyou might want the option to have chemotherapy even if many people rationally chose not to take it.

    In the end I expect ROI on longevity treatments (however you measure return) is likely to be pretty good and thus worth doing (unless it hits a massive road block).

  7. Genius,

    I think this is a promising sort of argument. I think the danger of it is that 'longevity research' might just turn out to be quite as broad as 'medical research', with just a narrower aim. If it really is that broad, then I agree that it's not really exceptionable in practice. The question that would still remain is how important an aim it should be. Should it be a derivative aim, subordinate to (just to choose an arbitrary example) improved health situations for the poor? If so, then longevity-related research should take priority only when (e.g.) it has a high likelihood of addressing, in an accessible way, a significant health problem in Third World countries. Likewise, on such a view, major steps in longevity research might be sacrificed in favor of very minor steps in (say) dealing with malaria or AIDS, if the results of the longevity research are likely to turn out to be expensive.

    And so forth. (There are, of course, many other aims that could be proposed; the one I've given is just an example.) So I think that the moral question really is not whether we should do longevity research (because in a sense we already are doing it, and couldn't help but do it as long as we are engaging in medical research), but how it should be related to other aims, and, in particular, whether it should be a major aim. That's where I'm much more skeptical than advocates for life-extension research.

  8. even the term Longevity research is too broard in a sense. Ie if I was to extend your life expectancy by releasing a retro virus that substituted peoples genes for "longevity genes" it would have a marginal cost of close to zero and easy to apply to the third world.
    Meanwhile other treatments might be ridiculously expensive.
    these things might be treated differently.
    I guess the questions being asked are things like
    1) should there be health research?
    2) are sudden deaths worse than slow ones?
    3) are predictable deaths worse than unpredictable ones?
    4) are fair deaths (ie everyone basically the same) different from unfair ones?

  9. In my opinion, welfare is additive to the extent that it is consumable. The first step towards rational analysis of longevity is to realize that no matter how long an individual manages to prolong life, he/she is subject to eventual death. Personal welfare does not come into the picture after death, so from a purely first-person perspective, death is acceptable at any point of time. What really constitutes a measure of personal happiness is debatable, but this measure is something that cannot be defined beyond death.

    As far as the social aspect of longevity is concerned, the stakeholders are both close relatives who are emotionally affected, as well as the rest of society that is culturally affected by the death of the individual, in terms of his/her potential contributions to society. Personally, I would prefer longer lives for my fellow humans, irrespective of the 'shapes' of their lives. My argument for this is two-fold. A longer life, with the exception of particular cases, raises the sum total of happiness amongst close relations. Secondly, the individuals contribution to society is proportional to the extent of his/her life. This is assuming that we provide the 'elixir' to everyone impartially. There may be anti-social elements whose longevity negatively impacts society, but they are in a minority. The same applies to 'non-contributors' to society.

    In summary, life-extension research is necessary, because longevity is immaterial from a personal standpoint and beneficial from a social one.

  10. "The idea is that if you can do everything appropriate for a good holiday in just two weeks, then there's really nothing to be said for staying a third week"

    sounds like McLean is an unimaginative killjoy who can't live without his job and for whom holidays are utilitarian things with which to do things -- sightsee, broaden once experience and knowledge etc. one of those poeople who do live to work rather than work to live. there are people like that, and god bless them, but i sincerely hope they won't try to curtail my lifestyle, -- which is to do nothing! (or at any rate nothing that does not please)

  11. Good points Ramnath, I was searching for but overlooking that perspective.

  12. McLean's argument reminds me of a statement of J-P Sartre (in one of his novels?) about the death of a friend in his twenties: that even though the death came early, the man's life was complete. Struck me then, and still does, as callous and smug.

  13. This kind of argument, where someone says that a "person's life was complete" is more of a consolation to those who are still living, and has no relevance to the subject himself. If you can imagine a really touching story in which a much-beloved character dies, the reactions of the readers could be considered analogous, albeit on a much smaller scale.
    The flip side of the coin is that others may feel offended that this guy claimed to know what the subject would have wanted.
    Either way, it's not a conclusion driven by rational factors, because there is no practical measure of a person's quality of life.

  14. I think quality of life is a bigger issue that quantity, but there is certainly some correlation there. People who live high quality active healthy lives tend to be rewarded with longer lives.

  15. And of course, there is that criticism of medical science adding years to our lives: why do all these extra years have to come at the end? Why can't we have the extra years in our 20s and 30s, when we could make best use of them!

  16. I generally agree strongly here but I am unsure of some unusual cases. For instance, if the extra six years that Sue had over Bob were spent very enjoyably doped up on heroin I'm pretty sure that ordinarily they still add substantially to the total quality of her life, though this draws a fairly clear cut between the desire fulfillment and story quality criteria, but I'm not sure that they do so if the previous year of her life (also the last year of Bob's life) was also spent doped up on heroin. My intuition is that sufficiently simple as to be qualitatively identical pleasures such as full years strung out on heroin might or might not actually be but are in my toy model are not additive, which fits well with many of my other positions on ethics and metaphysics, but for obscure reasons slightly aggravates my problems with the philosophy of mathematics.

  17. Michael - that's an interesting point. I agree that much of the plausibility of the 'additive' view depends on qualitative diversity (usually a safe assumption!). For the rare case of stacking identical experiences, I really don't know what to think. (There's a nice thought experiment along these lines over at Gyroid.)

  18. One potentially important example of experiences that may be identical enough not to stack and may not be comes from factory farms. It's plausible that factory farms aren't all that bad, but also plausible that they are good candidates for "worst thing ever". I'd definitely like to know which is true.


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