The finale of Steven Spielberg’s Indiana Jones and the Last Crusade (1989) sees the quest for the Holy Grail reach a dramatic conclusion. The film’s villain – the Nazi collaborator and artifact hunter Walter Donovan – knows that drinking from the sacred goblet will bring him eternal life. But from a table laid out with many false grails, he foolishly picks the most glittering cup of all. Donovan drinks his fill, but rather than receiving the gift of eternal life, he rapidly starts to age: his skin peels off, his hair falls out, and he turns into a skeleton that collapses into dust. As the immortal knight who guards the True Grail quips to Indy: ‘He chose … poorly.’

Moments later, Dr Elsa Schneider (also a Nazi) ignores the knight’s warning not to try to remove the Grail from the temple, causing the structure to collapse and the ground to split apart. Grasping for the prize of immortality, she attempts to reach the Grail before it falls into the bowels of the earth. So desperate is she to live forever, that she slips out of Indy’s grip, and plunges to her death. Indy himself almost suffers the same fate, until his father convinces him to ‘let it go’.

Immortality: a prize so great that some would die in attempting to secure it. But are they wise to do so? The Last Crusade suggests not. After all, not only are the two people who throw their lives away villains, but the knight who guards the Grail explicitly warns that the cost of living forever is having to stay in that very same temple, forever. And what sort of life would that be? Immortality – the film is suggesting – might be a curse, rather than a blessing.

Such a conclusion will not come as a surprise to philosophers who have considered the issue. In his essay ‘The Makropulos Case: Reflections on the Tedium of Immortality’ (1973), the English moral philosopher Bernard Williams suggested that living forever would be awful, akin to being trapped in a never-ending cocktail party. This was because after a certain amount of living, human life would become unspeakably boring. We need new experiences in order to have reasons to keep on going. But after enough time has passed, we will have experienced everything that we, as individuals, find stimulating. We would lack what Williams called ‘categorical’ desires: ie, desires that give us reasons to keep on living, and instead possess only ‘contingent’ desires: ie, things that we might as well want to do if we’re alive, but aren’t enough on their own to motivate us to stay alive. For example, if I’m going to carry on living, then I desire to have my tooth cavity filled – but I don’t want to go on living simply in order to have my cavity filled. By contrast, I might well want to carry on living so as to finish the grand novel that I’ve been composing for the past 25 years. The former is a contingent, the latter a categorical, desire.

A life devoid of categorical desires, Williams claimed, would devolve into a mush of undifferentiated banality, containing no reason to keep on going. Williams used as his example Elina Makropulos, a character from the opera The Makropulos Affair (1926) by the Czech composer Leoš Janáček. Born in 1585, Elina drinks an elixir that keeps her (biologically speaking) at age 42 forever. However, by the time she is over 300 years old, Elina has experienced everything she wants, and as a result her life is cold, empty, boring and withdrawn. There is nothing left to live for. Accordingly, she decides to stop drinking the elixir, and releases herself from the tedium of immortality.

Yet, as critics have pointed out, Williams’s argument isn’t really about immortality at all. Imagine that the natural biological lifespan of a human being was 1,000 years. In that case, in her 300s, Elina would have died comparatively young. Her problem isn’t that she is immortal, just that she’s gone on for too long already. If there’s a specific problem with immortality, it must lie elsewhere.

The moral philosopher Samuel Scheffler at New York University has suggested that the real problem with a fantasy of immortality is that it doesn’t make sense as a coherent desire. Scheffler points out that human life is intimately structured by the fact that it has a fixed (even if usually unknown) time limit. We all start with a birth, then pass through many stages of life, before definitely ending in death. In turn, Scheffler argues, everything that we value – and thus can coherently desire in an essentially human life – must take as given the fact that we are temporally bounded beings. Sure, we can imagine what it would be like to be immortal, if we find that an amusing way to pass the time. But doing so will obscure a basic truth: that because death is a fixed fact, everything that human beings value makes sense only in light of our time being finite, our choices being limited, and our each getting only so many goes before it’s all over.

Scheffler’s case is thus not simply that immortality would make us miserable (although it probably would). It’s that, if we had it, we would cease to be distinctively human in the way that we currently are. But then, if we were somehow to attain immortality, it wouldn’t get us what we want from it: namely, for it to be some version of our human selves that lives forever. A desire for immortality is thus a paradox: it would frustrate itself were it ever to be achieved. In turn, Scheffler implies, once we’ve reflected carefully on this deep fact about ourselves, we should junk any residual desire to live forever that we might still have.

You might think you want to live forever, but reflection should convince you otherwise

But is it quite so clear? Can we not sympathise, even just a little bit, with Donovan and Schneider’s grasping after the Holy Grail? What is interesting in this regard is that, when we return to wider popular culture, instances abound of immortality being presented not as a blessing, but a curse.

In Jonathan Swift’s satire Gulliver’s Travels (1726), the protagonist meets the peculiar race of ‘Struldbrugs’, humans born with a strange mark on their foreheads, indicating that they will live forever. Initially thinking that these must be the happiest of all beings, Gulliver revises his view when he learns that Struldbrugs never stop ageing, leading them to sink into decrepitude and insanity, roaming the kingdom as disgusting brutes shunned by normal humans. Or consider Alfred, Lord Tennyson’s poem Tithonus (1860), where an immortal narrator describes his physiological and psychological decay brought on by an endless life, and the horror and loneliness of being trapped in such a state.

It seems, then, that both philosophers and popular culture keep trying to tell us the same thing: you might think that you want to live forever, but reflection should convince you otherwise. And yet, if this is ultimately true – as philosophers and popular culture seem to want to say that it is – then another question arises: why do we keep needing to be told?

There is something both deeply and persistently appealing about the idea of immortality, and that cannot be dispelled by simply pointing to examples where immortality would be a curse. To see this, we have to think a little more carefully about what a desire for immortality might in part be about.

On the face of it, a desire for immortality most obviously seems to be a response to the fear of death. Most of us are afraid to die. If we were immortal, we could escape both that fear and its object. Hence, it seems, a desire for immortality is simply a desire not to die. In the face of this, what philosophers, poets and novelists remind us of is that there are fates worse than death. Immortality might itself turn out to be one of them. If so, we should not desire to be immortal. No sane person, after all, wants to be a Struldbrug.

But when we look more closely, we see that fear is not the only important response to the fact of death. Here it is useful to turn to the words of the Basque philosopher Miguel de Unamuno in The Tragic Sense of Life in Men and Nations (1912):

I am presented with arguments … to prove the absurdity of a belief in the immortality of the soul. But these ratiocinations do not move me, for they are reasons and no more than reasons, and one does not feed the heart with reasons. I do not want to die. No! I do not want to die, and I do not want to want to die. I want to live always, forever and ever. And I want to live, this poor I which I am, the I which I feel myself to be here and now, and for that reason I am tormented by the problem of the duration of my soul, of my own soul. I am the centre of my Universe, the centre of the Universe, and in my extreme anguish I cry, along with Michelet, ‘My I! They are stealing my I!’

Part of what Unamuno is relating here is outrage and anger that something is being taken away from him (‘they are stealing my I!’). Unamuno is imagining the situation that most of us do when we are contemplating our own deaths: not a distant point of decrepitude, aged 107, trapped in a hospital bed, in an underfunded care home – but rather death as claiming us before we are ready. In other words, death is often thought of, and experienced (for example, by the terminally ill), as a sort of personal affront, a taking-away of one’s time, before one wants to go. It is, in other words, the most fundamental attack on one’s agency.

We do not just fear the inevitable fact of death, we also resent it as a personal affront. This is one reason why in Western culture death has often been literally personified: not a brute, indifferent, merely biological occurrence, but a Grim Reaper who comes to claim your individual soul. Likewise, it’s no coincidence that the Grim Reaper can be bargained with. If you beat him at chess – so the legend goes – he has to let you go. You, as the agent, can try to stay in control.

Of course, the harsh reality is that death comes either ‘too early or too late’

What this means is that there might be – contrary to Scheffler’s argument – a coherent desire for immortality after all. This is because desiring immortality might not simply be about having a desire to live forever. It might instead be a desire to control when we ourselves will die, choosing to end it all only when – and not before – we ourselves are ready.

Indeed, such a possibility is depicted in the ancient Sanskrit epic poem Mahabharata, where the great warrior Bhishma is granted the boon of ‘death upon desire’. Bhishma cannot die until he wills it – but that does not preclude him from later falling in battle at the hands of Arjuna, finding himself incapacitated on a bed of arrows. Still, even when so incapacitated, Bhishma is not yet ready to die. He elects first to lie on the field of battle and pass on his wisdom to Yudhishthira, until he has decided that the time has come for him to depart. Bhishma prepares himself for death, and when he is ready, draws his life to a close.

This capacity for ‘death upon desire’ is presented in the Mahabharata explicitly as a boon. And the contrast with immortality as being somehow unable to die is clear. Had Bhishma been impaled on the bed of arrows while being unable to die – and hence presumably having to stay there forever – he would certainly have laboured under a curse. As it is, things were different. Yet Bhishma’s boon seems coherent as something we might want for ourselves. It would eradicate fears of dying before we are ready, at the same time as preserving a capacity to call it quits when we’ve had enough – all the while accepting Scheffler’s point that eventually we will need to die for our lives to be worth living in the first place.

Of course, the harsh reality is that most of us will find that death comes – in Williams’s phrase – either ‘too early or too late’. Too early, if we are not yet ready to go. Too late, if we’ve gotten to the point where life is already not worth living anymore. Indeed, we hardly need philosophers to convince us that, for many people, there are fates worse than death: assisted dying clinics in countries such as Switzerland demonstrate that many people will choose to die rather than carry on in gross physical pain or continued indignity, especially when there is no prospect of recovery. It is a striking feature, however, of most societies that they deny people the choice to die at the very point when they most rationally desire it.

Immortality is, obviously enough, an impossible fantasy – hence it cannot be a genuine solution to the unfortunate yet elemental facts of the human condition, nor an answer to the fraught complexities surrounding euthanasia as regards both social policy and moral judgment. Nonetheless, the reason such a fantasy endures in popular imagination – as well as being a target for philosophical reflection – is that it taps into something important about our attitudes towards death. We are not simply afraid of death, we also resent it, because it is experienced as an assault on our personal agency. We can fully control our own deaths in only one direction – and that, of course, is usually no comfort at all. As with so many things in life, death turns out to be more complicated than it first appears.