Imagine you are offered a trustworthy opportunity for immortality in which your mind (perhaps also your body) will persist eternally. Let's further stipulate that the offer includes perpetual youthful health and the ability to upgrade to any cognitive and physical technologies that become available in the future. There is one more stipulation: You could never decide later to die. Would you take it? Metaphysician and former British diplomat Stephen Cave thinks accepting such an offer would be a bad idea.

Cave's fascinating new book, Immortality, posits that civilization is a major side effect of humanity's attempts to live forever. He argues that our sophisticated minds inexorably recognize that, like all other living things, we will one day die. Simultaneously, Cave asserts, "The one thing that these minds cannot imagine is that very state of nonexistence; it is literally inconceivable. Death therefore presents itself as both inevitable and impossible. This is what I will call the Mortality Paradox, and its resolution is what gives shape to the immortality narratives, and therefore to civilization."

Cave identifies four immortality narratives that drive civilizations over time which he calls; (1) Staying Alive, (2) Resurrection, (3) Soul, and (4) Legacy. Cave gracefully marches through his four immortality narratives citing examples from history, psychology, and religion up to the modern day. "At its core, a civilization is a collection of life extension technologies: agriculture to ensure food in steady supply, clothing to stave off cold, architecture to provide shelter and safety, better weapons for hunting and defense, and medicine to combat injury and disease," he writes.

In the Staying Alive narrative Cave opens with the quest of the First Emperor of China to find the elixir of life but lands us soon the 21st century where transhumanists aim to use modern science to finally achieve the goal of perpetual youthful life. He notes that in the last century, humans have in fact doubled average human life expectancy.

Why not simply repair the damage caused by aging, thus defeating physical death? This is the goal of transhumanists like theoretical biogerontologist Aubrey de Grey who has devised the Strategies for Engineered Negligible Senescence (SENS) program. SENS technologies would include genetic interventions to rejuvenate cells, stem cell transplants to replace aged organs and tissues, and nano-machines to patrol our bodies to prevent infections and kill nascent cancers. Ultimately, Cave cannot argue that these life-extension technologies will not work for individuals but suggests that they would produce problems like overpopulation and environmental collapse that would eventually subvert them. He also cites calculations done by a demographer that assuming aging and disease is defeated by biomedical technology accidents would still do in would-be immortals. The average life expectancy of medical immortals would be 5,775 years. Frankly, I will be happy to take that.

Resurrection is his next immortality narrative. Of course, the most prevalent resurrection story is that of Jesus of Nazareth 2,000 years ago. The New Testament explicitly states that one day every individual will once again live in his or her real but improved physical bodies. Physical resurrection is also the orthodox belief of the other two Abrahamic religions, Judaism and Islam. Thus, Cave notes, half of the world's population officially believes in the future resurrection of their physical bodies. He adds, however, that many Christians, Jews, and Muslims actually subscribe to another immortality narrative, Soul.

Cave identifies three major problems with the Resurrection Narrative: the Cannibal problem, the Transformation problem, and the Duplication problem. Briefly, if resurrection is to mean anything, it must mean that a specific individual is brought back to life. The question is what happens when atoms have been shared by more than one person: Who gets to use the specific nitrogen and carbon atoms when everyone is brought back to life? I don't think that that is much of problem since atoms are interchangeable and presumably God could simply put any random carbon and nitrogen atoms back in the same places they were in your physical body. They needn't be the exact same atoms that you had when you died.

The Transformation problem is harder. Many believers would have died old, decrepit, and demented. That's not how they believe they will be resurrected; they expect to get better, incorruptible bodies. By being thus transformed would the resurrected believer really be the same person who had died or a different person? And then there is the problem of duplication. God could not just reassemble a believer as she was when she died, he could also reassemble her as a 5-year-old girl. Cave argues that these three problems calls into question the notion that it would truly be a specific individual believer rising from the grave.

Besides these ancient resurrection dogmas, modern technophilic thinkers have devised a couple more: cryonics and mind uploading. Cryonicists aim to avoid the three ancient resurrection problems by having their bodies frozen at minus 276 degrees Fahrenheit in liquid nitrogen with idea that future technologies will be able to revive them. Cryonicists believe that reviving individual brains with their unique patterns and history would be the way to guarantee that specific individuals are actually brought back to life.

Cave notes that this focus on preserving a person's mind leads other modern would-be computational resurrectionists to argue for uploading minds (information encoded in an individual's brain) onto another piece of hardware, an electronic avatar, a robot, or another brain which would be psychologically identical to the original mind. Cave argues that computational resurrection does not actually achieve immortality for a specific individual, but merely makes an exact psychological copy of him. There is the additional problem that if minds can be digitized they can be duplicated many times. If this occurs who then is the original resurrectee? "When you closed your eyes on your deathbed, you could not expect to open them again in silicon form," he explains. The result of mind uploading "would all just be high-tech ways of producing a counterfeit you."

Counterfeit? Counterfeit means to make a copy with the intention to deceive or defraud. I doubt that people who decide to take advantage of mind uploading would be defrauded or deceived. Even if digital duplicates were made of the same individual's mind, I suspect that they would have no problem with that—the more versions of their specific memories, desires, and psychology the merrier.

Cave does not address one other popular version of how computational immortality might occur. As the 21st century advances our bodies and minds will be increasingly integrated with digital appliances of various sorts, e.g., more and more of our memories and reasoning abilities could be located on silicon (or whatever quantum computations devices come later) and accessed via radio. Eventually more and more of the information that makes up an individual's mind will have migrated into these digital devices. When the biological portion of an individual's techno-complex eventually dies it may be regretted but the event will not significantly disrupt the continuity of the individual's self-consciousness.

The most popular immortality narrative is Soul. Most Christians now believe that their souls, which persist after death, will be reunited with their resurrected bodies. Souls thus solve a lot of the identity problems associated with the earlier Resurrection narrative. Cave argues that Soul narrative resolves the Mortality Paradox by denying "that the failing body is the true self, identifying the person instead with exactly that mental life that seems so inextinguishable." In Christianity all souls are equal before God, so if the omnipotent and omniscient Creator of the universe is interested in your life then who are your politicians to ignore your desires?

What about the afterlife? Cave cites American evangelist James L. Garlow who says that in Heaven "your every desire is satisfied more abundantly than you've ever dreamed." But what if your desire is to be reunited with your wife who instead desires to spend her eternity with her childhood sweetheart? A more sophisticated theocentric view of the soul's afterlife is that Heaven is the eternal exaltation of God. But what can this mean? Cave points out that an afterlife without time is not really a life at all. "Everything that makes up a human life—experience, learning, growth, communication, even singing hosannas—requires the passage of time. Without time, nothing can happen; it is a state of stasis, a cessation of thought and action," he argues. "The attraction of the soul view was the unique aura it gave to every individual life, but its logical conclusion is an eternity of nothing, with life negated altogether."

The major Eastern religions, Hinduism and Buddhism, also subscribe to versions of the Soul narrative involving cycles of reincarnation. Cave points out though that both religions' accounts of souls are pared down to being some kind of vague continuum of awareness. After death your individual experiences, memories, hopes, desires are all forgotten as your soul moves from one body to the next. Cave is correct when he asserts, "If you have a soul, yet it does not take your mind, personality, or consciousness with it, then its survival after the death of your body should be of as much interest to you as the survival of your toenails."

Cave tries to imagine the sorts of scientific experiments that might show that people do have nonmaterial souls. For example, he asks if souls are maintainers of awareness why is it that when our bodies are knocked unconscious or anaesthetized that our nonmaterial souls apparently lose consciousness too? If your soul is the essential you it must harbor your emotions, memories, ability to speak, and moral norms. However, neuroscience shows that damage to specific areas of your brain can eliminate all of these qualities that make up you as an individual. "Those who believe that the soul could preserve these abilities after the total destruction of the brain in death must explain why the soul cannot preserve these abilities when only a small part of the brain is destroyed," challenges Cave.

The final immortality narrative is Legacy. It comes in two varieties: fame and progeny. Achieving fame and glory in the here-and-now have some obvious benefits, e.g., increased status, more money, more power, and more opportunities to mate. In addition, fame means that you will be remembered by later generations. Cave considers the bundle theory of the self in which bits and pieces of your memories, personality, and images continue to exist in the cultural realm after your death. But you are still dead—your consciousness and personality is not dispersed into books, movies, or the minds of fans. And research shows that it takes only 70 years after our deaths before most of us are forgotten. Can you name all of your great-grandparents?

People also want to live on through their children. Your genes live on through your children, but genes are simply machines for making proteins in response to environmental cues. You are merely the disposable container that genes use to make more copies of themselves. Reproduction, as satisfying as most people find it, is no way to preserve one's individual consciousness.

Cave concludes, "All four fundamental immortality narratives are illusions. None of them will enable us to live forever." But even if one of the immortality narratives were true or possible, Cave argues that on the one hand, boredom and apathy would eventually set in after one has done and seen everything, and other the hand, the prospect of an infinite future means that there is no urgency to do or see anything resulting in paralysis. Meaningful lives require a time limit, he argues.

Since the immortality narratives fail, we are still left with our fear of death and non-existence. To overcome our fears and to escape the clutches of the Mortality Paradox Cave advocates turning to what he calls the Wisdom narrative. He thinks that he has made the case that a genuinely unending life would most likely be terrible. However, he acknowledges that this realization is unlikely to convince people that it's great to be dead. So the next step toward wisdom is to accept the notion that the "fear of being actually dead is nonsensical." And the final step is to cultivate virtues that undermine our will to live forever and thus reduce our existential angst.

The model for realizing that the fear of death is nonsensical is the Greek philosopher Epicurus who wrote, "While we are, death is not; when death is come, we are not." Cave interprets Epicurus as chiefly arguing that we should not fear the state of being dead. Being dead is nothing, so why fear nothing? Cave asserts that wisdom comes when we realize "that we can never be dead, that fearing being dead is therefore a nonsense." Oddly, I don't think that I (and many others) suffer from Cave's Mortality Paradox—I can imagine non-existence. Consequently, with regard to death there is nothing to fear but nothing itself.

In order to further undermine our fear of death Cave counsels that we adopt the three virtues of empathy, mindfulness, and gratitude. Empathy reduces our fear of the death by shifting the focus from ourselves; mindfulness encourages us to enjoy the present moment; and gratitude makes us conscious of what an incredible stroke of luck it is to be alive in the first place. It seems to me that the cultivation of these virtues is valuable in its own right, and if such cultivation happens to reduce one's fear of death then that's a nice bonus.

As comforting as they have been and as much as they have inspired people to build civilizations, Cave is right that the Resurrection, Soul, and Legacy narratives are illusions. So too is the modern version of the Staying Alive narrative if it is interpreted such that it results in infinite life rather than radically increased life expectancies. However, toward the end, Cave grants the transhumanists who are pursuing medical immortality would not suffer from the problem of eternal boredom since they would eventually die of accidents in any case. And of course, if the radically long-lived did get bored they could simply stop whatever treatments they are using to maintain their lives.

Finally, back to the question of whether you would accept an offer of true immortality—your consciousness (and perhaps your body) persisting eternally. Cave clearly believes that it would be a bad idea. He cites many legendary examples in which mortals are granted immortality who come later to regret it. Mostly because they become very bored. And yet, as far as I know, no one seriously claims that God suffers from ennui.

Nevertheless, before I read Cave's book, I would have answered absolutely I would accept such an offer. Now, I am thinking about it a bit more. Since I need more time to contemplate the upsides and the downsides of eternal life, I will happily accept any legitimate offer for a dramatically extended and healthy lifespan.

Science Correspondent Ronald Bailey is the author of Liberation Biology (Prometheus).