Imagine this scene: you,a life extension supporter,are with a group of people talking about this and that,and,at one point,the opportunity to mention life extension presents itself.You expect people to react to it with"Yay!Longer life in good health!No more aging!"but reality doesn't quite match up to your expectations;rather,all you get is the frustration of looking at how everyone nods approvingly when somebody puts on a great philosopher's hat and asks rhetorically:"Would it really make us happier if we could live to 150?"Boy,is that ever irritating.
Actually,it isn't really the specific question per se that is irritating—basically,whether living much longer than the current average would bring us more happiness—but rather that nobody ever asks whether living to 80 years old,for example,would make you any happier than you would be if you lived to only 40.If the first question is legitimate,the second one should be as well,and,by induction,you could work your way down to zero and ask whether being born makes you any happier than not being born.(Arguably,it doesn't—babies inside the womb are generally quite peaceful and blessed looking,which is more than can be said of their mood once they pop out,but few people would agree that this is a good reason to abort each and every fetus.)
Maybe it is somehow established that living to 80 is sure to bring more joy than checking out at 40?Maybe it is equally well proved that living to 150 doesn't make you any happier than hopping off the life train at 80?(Hardly—I don't know of any 150-year-olds complaining about it,and neither do you.)
The point is,the idea that living to this or that age would make you happier than you would be otherwise is flat out stupid.The fact alone of having reached a certain age,whatever it might be,doesn't necessarily bring any happiness.Hang on—you might think—of course living to 80 is better than dying at 40,because that's a solid 40 extra years during which there is a ton of things you could do to make yourself much happier;well—bingo.That's precisely the point.
If you won a stay abroad in a nice hotel,but you were obligated to never leave your room,it probably wouldn't make you any happier if the stay was four weeks long rather than just one;conversely,if you were allowed to go out and do what you like,four weeks would be a much better deal.If living to 80 rather than just 40 is good because it gives you the chance to do more of what you like,then it doesn't make sense that living to 150 rather than just 80 shouldn't be good for the exact same reason.
This is generally the point of the reasoning when people say at least either of the following:
A) Past a currently normal lifespan,you wouldn't have much else left to do.
B) Past a currently normal lifespan,做任何事情,你也会不健康let alone enjoy it.
About point A—let's be honest here: by the time you're 80,you probably won't have managed to go through一半your bucket list,never mind running out of things to do in general.Besides,say that you reached the bottom of your life's to-do list at age 45;would you be more likely to look for more stuff to add to the list or assisted suicide options?Exactly.
Point B definitely has some merit—if your health sucks,your life might too,but there still are two very valid objections to this.The first is that there are unlucky people out there who were struck at a young age by diseases bad enough to make their lives a constant struggle but not enough to kill them;think of people stuck on a wheelchair or on a bed or any other seriously disabled or sick people.Not all of them decide to call it quits—despite their ill health,some people would still rather live and enjoy whatever nice things they still are able to do.So,no,it's not 100% guaranteed that you'd rather be dead than be 90.
Secondly,if the people you were talking to in the first paragraph brought up point B to object to life extension,that's a dead giveaway that they weren't paying too much attention when you said that life extension is about extending your healthspanfirstand that lifespan extension is simply a most welcome and—let's face it—desiredside effect."Quality,not quantity"might be acceptable when talking about the duration of life only if significant healthspan extension is not in the cards,but it's just a pretentious thought-terminating cliché otherwise—if quality is better than quantity in every case,then anyone who has had a wonderful childhood would be better off dying before adulthood,when problems of all kinds are bound to show up and decrease that person's quality of life.
Anyway,there is a much more effective consideration that we can make to shoot down the whole rhetoric about whether longer lives mean more happiness.Let's go all the way back to 300 years ago,when we had no sanitation,no vaccines,and no hygiene and doctors were closer to butchers than to healthcare professionals.The average Joe,who probably had an unfulfilling,underpaid,menial job and far too many mouths to feed,could maybe look forward to a 40-year life expectancy.Exciting,isn't it??
Now,suppose our average Joe heads to the local tavern to chat to his friends,and,at some point,he starts daydreaming of a future world where infectious diseases are kept on a tight leash,clean water comes to you at home rather than the other way around,and doctors delay your demise rather than hasten it,allowing everyone to live well into old age.
One of his friends objects,"Would it really make us happier if we could live to 80?"His friend could make a rather good case that all they could look forward to would be more of their crappy jobs and the diseases of old age—at the time,treating them was absolutely out of the question—yet,we have already noted before that living to 80 is better than living to only 40,or,at the very least,having the option to is better than not having it.So,our friend from the 1700s would be wrong,and for the same reasons,so is objecting to life extension by covertly implying that it wouldn't make us happier.
Unless you'd rather only make it to 40,that is.