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!)