That argument against anti-ageing therapies was something along the lines of each individual getting only once chance (at life, presumably), in the sense that the right number of chances to get is one and each person should indeed get only one of them. It’s easy to see the basic flaws of this argument, and for the sake of completeness I will deal with them first before going on to the more important one.
The most obvious flaw is that the argument assumes that, somehow, anti-ageing therapies give you more than one chance at life. That certainly doesn’t hold water, because it would imply that once you miss your first chance (situation that would materialize only with your death) you get another one (i.e. you are somehow resurrected). If we accept that you get “more than one chance” just because anti-ageing makes your life longer than it otherwise would be, then the same must be true of anything else that makes your life longer than it would be otherwise, like for example being cured of a life-threatening disease, getting a vaccine, exercising or even just paying attention when you cross the street—or eating, for that matter.
Anti-ageing medicine doesn’t bring you back from the dead, so if your problem with it is that everybody should get only one chance, I think you don’t have a problem at all.
The second flaw is the assumption that everybody should, in fact, have just one chance. Even assuming, for the sake of the argument, that anti-ageing therapies effectively give you “extra lives” (and they don’t), why is it so that everybody should get only one? Who decided that? If that’s your personal philosophy I’m very much okay with it—you decide what to do with your own life, or how many “chances” should you have to begin with, but just like I can’t (and don’t wish to) force anyone to have more than one “chance”, you can’t force anyone to have just one, particularly if you can’t provide any compelling, well-documented reason for which this is how it should be. I’d be content even just with some information on who gets to decide on the number of chances and who gives them, keeping in mind that, since nature isn’t an intelligent agent, it’s excluded from the list, and that God is not an agent on whose existence everyone agrees nor is there any evidence for it.
The main flaw is actually the worst, one that stems from not thinking thoroughly about everything and everyone; I agree that this is hard to do, but you simply can’t avoid it if you want to make generalizing statements like “everyone should only get one chance”.
Let’s consider things in the context of a world without anti-ageing therapies, and thus with age-related death and a quite limited, very well defined lifespan (i.e. our current setting, unfortunately). From a rather cynical perspective, if you mess up your one and only chance by doing something wrong, it’s your fault and on your deathbed you’ll only have yourself to blame. I actually disagree with this attitude, and I’d rather give anyone another chance than proclaim myself judge and deem that nobody should get more than a single one; nonetheless, things can get morally more deplorable than this.
What about people whose “only chance” was ruined by circumstances independent of their will and actions?
Imagine you have car accident because somebody else didn’t see the red light. It’s not your fault if you won’t be able to walk ever again, still your only chance at life is ruined, or severely damaged. Of course you can claim that it isn’t, because you’re full of will power and, in fact, the accident will strenghten your wish to live and your need for accomplishment, and lead you to successes that you probably wouldn’t have gotten to had you not had the accident. I am proving my own argument tragically wrong, it would seem.
Well, I don’t think so. What I have written above is the sort of stuff you read on motivational posters on the Internet, and while it is true that one can gain more strenght out of something as tragic as the accident above, that same stuff doesn’t seem to take into account the ordeals that a severely, permanently injured person has to go through, even in the form of things that are easypeasy for the rest of the people, nor does it change the fact that, regardless of your ability not to let yourself go even in the face of tragedy, it’s always better to prevent tragedy in the first place; and even if you do get super spiritual strength after losing your ability to walk, I’m sure most people would rather not exchange the latter for the former: after all you can always try and improve your spiritual strength, while it’s not so easy to get your legs functioning again after your spine has been snapped.
Accidents are not the only chance-ruiners; some people had their chance ruined from the very beginning, because they were born with a condition that makes their life way harder than it otherwise would, and some others were struck by a crippling disease only later on.
It might seem that I’m wandering from the topic, but I’m not. The people I talked about above didn’t just end up with the shortest straw without even getting to pick; unfortunately, as time goes by, their condition is going to go from bad to worse, because biological ageing doesn’t just bring along diseases that you didn’t have before, but it also makes virtually every pre-existing disease or ailment worse. It seems quite unfair and myopic to say that “everyone should get only one chance” when there are people out there whose only chance has been ruined by forces out of their control, and before you reply that life’s not always fair, let me remind you that making it more and more fair is all human progress is about.
Rejuvenation biotechnologies wouldn’t just cure billions of people of age-related diseases, but would prevent the life of severely injured, sick and disabld people from getting considerably worse with age; and on top of that, anti-ageing therapies have the potential of making them live long enough to see the day when the condition that has been afflicting them for so long can be cured. They could see the day they can walk again, and undo the damage done to their only chance, which will hopefully last for yet very long.
In the end, it isn’t all that wrong to say that we have only one chance; that’s exactly the reason for which we shouldn’t take any chances with it.