Some people spent a fair amount of time debating philosophical points on what it would be like to live for centuries or longer, a prospect that will become an actual possibility before the end of the century, enabled by the development of rejuvenation biotechnologies. There is nothing wrong with that as a hobby, but the most disconnected, ridiculous arguments against a long life span have a way of finding their way back into discussions over today's funding for aging research. Even the polemics in favor of radical life extension drift away into points that have little to do with day to day experiences of life, such as this one in which the author considers that aging into different opinions and ideals a century from now is actually undesirable and a viable argument in favor of dying instead.
Yet that prospect is hardly terrible; we are all living with it comfortably already, after all. No-one really expects to be exactly the same person twenty years from now, let alone hundreds were they available. Life is change and motion. The best argument for radical life extension via the medical control of degenerative aging is the simple one: that today we'd like to be alive and active tomorrow, and that was the state of things in all of our past days.
In the future it is likely that advances in medicine will grant us the opportunity to prevent the process of ageing. The question of whether eternal life would be a good thing will then be of the utmost practical importance to humanity. In this essay, I claim that it would be. We need to begin by working out our answer to Lucretius' view that death is not a bad thing. Put another way, we first need to find out what it is that makes us think life is valuable and worth living, and then we can see if the beliefs we end up committed to in light of our answer to this question also commit us to believing that eternal life would be desirable.
The Lucretian shifts the scope of the argument to consideration of whether death is a bad thing for the person who dies. However, this separation of the interests and happiness of persons who have close relationships is problematic. While others conclude Lucretius is wrong merely because there must be at least something valuable in life, I want to draw attention to a specific good that I believe is, and we generally agree to be, valuable, namely having positive personal relationships with others. In arguing that death is not a bad thing or not a bad thing for the person who dies, Lucretius is forgetting that death is what all too often robs us of the opportunity of creating, continuing, and/or developing further, positive relationships with others.
If my body lived for another 200 years, but my beliefs, aims, and way of living were utterly different from what they are now by the end, would it really be me that was still alive? It would be extremely difficult to maintain one's personal identity, understood this way, over a long time. Other authors doubt that such a psychologically disjointed life, with mere bodily and no personal continuity, is desirable. In response, I suggest applying the idea that relationships with others are central to the meaning of life to the problem of personal identity. Though the existence of these sources may be finite, their influence need not be. While it would be difficult to keep these influences in mind as time passed, an immortal person could take measures to actively remind themselves of them in writing, visually (with photos etc.) or memory if she showed sufficient discipline.
Another concern about the prospect of immortality is that it may become boring and therefore meaningless. What pursuits could be so interesting they would never get boring? I do not think the dismissal of intellectual contemplation as a candidate is convincing. Further, we should not ignore that as time passes, radically new pursuits (and relationships) will become available that, at that present time, we may have no way of conceptualizing (just as a caveman would scarcely have been able to conceptualize a video game). Further, some pleasures do not have diminishing marginal returns, such as the enjoyment of fine food. This point can, again, be made more convincing if we consider the element of social relationships. It is no coincidence that a recurrent and problematic question that people frequently raise during discussion of this topic is whether one's loved ones would be immortal too. Eating nice food might eventually get boring, but would spending time enjoying life with loved ones?