The best statement of those arguments that I have seen is Dinesh D'Souza's Life After Death: The Evidence (Regnery Publishing, 2009). What is most interesting for me is that D'Souza claims to rely primarily on purely rational scientific and philosophic thinking that does not depend on religious faith. This is the first of a series of posts on D'Souza's arguments.
In my responses to D'Sousa, I have been influenced by Victor Stenger's book chapter "Life After Death: Examining the Evidence," in The End of Christianity, edited by John W. Loftus (Prometheus Books, 2011), 305-32, which is available online. There is a series of YouTube videos of a debate between D'Souza and Dan Barker, which lays out some of the issues.
According to Stephen Cave, there are four possible ways that we might achieve immortality. The Staying Alive Narrative says that we could become immortal if we could find a way to postpone death indefinitely. The Resurrection Narrative says that even if death is unavoidable, we might be brought back to life. The Soul Narrative says that even if our bodies must die, our souls can live forever because they are immaterial and thus not subject to bodily decay, and our souls are the most essential part of us. Finally, the Legacy Narrative says that we can live on after death through those that live after us--either because they remember us or because they carry our genes.
D'Souza says nothing about the Staying Alive Narrative and quickly dismisses the Legacy Narrative (3-4). So he's left with the Soul Narrative and the Resurrection Narrative. He recognizes that the Soul Narrative came from Plato and was adopted by Christian theologians like Augustine, while the Resurrection Narrative was introduced into Christianity by Paul in the New Testament. D'Souza never clarifies the relationship between these two forms of immortality.
According to the orthodox Christian tradition defended by someone like Thomas Aquinas, our souls are separated from our bodies at death, but then they must be reunited with our bodies at the Second Coming of Christ and the Last Judgment, when the saved will go to Heaven for eternal reward, and the damned will go to Hell for eternal punishment.
Furthermore, according to Aquinas, this resurrected body must be a real living body. And since all living bodies are ageing bodies, the resurrected bodies must have a specific age. Since Jesus rose again at about age 30, that age must be the perfect age for the body, and so, Aquinas reasons, when human beings are resurrected, they will all have bodies of the same age--30 years old. Those who died as children will be moved up to age 30, and those who died in old age will be moved back to age 30 (ST, suppl., q. 81, a. 1).
But then we must wonder, when people wish for immortality, is this what they're wishing for--to be frozen eternally at one moment in time? Shouldn't we say that this kind of immortality would be death?
This points to the problem of personal identity. If my wish for immortality is a wish that I as a unique individual with a unique personal identity should live forever, then I want to be sure that whatever lives forever is really me and not just a copy of me. As the embodied person that I am, my experience of myself combines my ageing body and my self-conscious mind as inseparable. So it's not clear to me that an immaterial soul would really be me. It's also not clear to me that a resurrected body would really be me if that body was frozen at the age of 30.
D'Souza never faces up to this problem. For example, he speaks about the Buddhist conception of immortality in which we must realize that "our individual souls are identical with the oneness of ultimate reality." He explains: "Part of our enlightenment is to recognize that the very concept of 'I' is illusory; in reality, there is no man behind the curtain. The term nirvana literally means 'blowing out,' and in case you're wondering, you are the one who must be blown out, like a candle" (51). Is this what people wish for when they wish for immortality--to have their personal identity blown out? If one's identity is blown out, isn't that death?
There's a similar problem with bodily resurrection. D'Souza indicates that our resurrected bodies will have to be very different from the earthly bodies that we have now, because our resurrected bodies will have to be eternally imperishable and ageless. But if my resurrected body is so different from the body that I have known in my life, will this be my body? Or will it be only a copy of my body? Here, again, it seems that my personal identity as the real embodied mind that I am has been blown out.
As I have indicated in my blog post on Wallace Stevens's poem "Sunday Morning," we should consider the possibility that living forever is not desirable, because living timelessly and changelessly would not be really living, and that in living the lives that we have, "death is the mother of beauty."