W Harwood, harwood.will@gmail.com
November, 2025. Book coming, possibly
Organic content: no AI was used here
Lucretius wrote De rerum Natura in the first century BC. It is a poetic explication and exploration of Epicurian philosophy, and contains a wonderful argument against the fear of death, of our own personal extinction:
Look back -- think how little you care
For the endless ages of time
That passed, unknown, before your birth.
Nature holds a mirror for you
In which that time is reflected
And welcomes the infinity
That will come after you have died.
Why fret? Where is the tragedy?
Death is a greater peace than sleep.
De rerum natura was lost for over a thousand years, then helped kindle the Renaissance. Michel de Montaigne was deeply influenced by it, and wrote in his copy:
As there are varied movements of atoms, it is not incredible that once upon a time atoms came together, or will come together again, so that another Montaigne is born.
Almost a hundred years later, David Hume wrote in his Treasise of Human Nature:
[W]hen I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never can observe any thing but the perception. When my perceptions are removed for any time, as by sound sleep; so long am I insensible of myself, and may truly be said not to exist.
The sceptical, atheistic intellectual tradition of Hume, Montaigne, and Lucretius is alive in the modern scientific, physicalist view of the universe. Let's call it the common-sense view, that there is only the physical world. If life is like Bede's sparrow flying through a lighted hall, then nothing exists but that hall. It is common sense because we know that the body does not last forever so why should our consciousness, so manifestly supported by the body, continue to exist after the body has ceased to function? We are exactly our physical bodies, there is no separate mind-stuff or lurking ghost. We are special arrangements of matter, so special that we can think and feel and somewhat know ourselves, as partial and temporary perspectives on the universe. An endless age of time passed before we existed, and an infinity will pass after we have gone.
Implicit in the common-sense view is a belief in oblivion. It is impossible to imagine not existing: to imagine a thing is to picture yourself next to it, and yet there is no self to picture anywhere. A "special way to be afraid", as WH Auden has it, which religion's "vast moth-eaten brocade" tried to dispel. But we will stay with the common-sense view, and use it to vanquish oblivion in a quite surprising way.
Because by taking seriously and consistently the common-sense view, we will argue that there is no oblivion; that while objectively surely every body dies, subjectively we are eternal. This is subjective immortality.
Lucretius gives us two questions:
He considers that both questions are the same question and have the same answer:
But we want an argument against oblivion. Consider the first question, and ask: what was it like, for you, a million years ago? Of course it was like nothing. And yet, your subjective experience was a million years immediately passed, and you became conscious for the first time. Consider the second question, which is another way of asking "what is it like to be dead?" Recall Michel de Montaigne's note, of chance forming another de Montaigne (of atoms eventually becoming a mountain). If we are just our physical beings, then consciousness simply is a certain arrangement of atoms. In a universe that is infinitely wide or lasts infinitely long, every pattern will reappear, and with it (since there is nothing but the pattern) that consciousness will reappear too. You die, and the pattern of your consciousness is lost. Wait long enough, and by pure random motion, whatever arrangement is needed to be you will form, somewhere in the universe. The distance of time or space is immaterial, as nothing is travelling, nothing exists until, of a sudden, it does.
This gives us an answer to the second question, and it is the same answer as to the first:
Not existing in the future is the same as not existing in the past. In both cases, what it is like is: you are immediately conscious.
Why should the future be infinite? Or even if infinite, why should patterns continue to form? Space is expanding, the universe thins and cools, everything is moving away from everything else. Picture a little host of particles coming together to make a shape, then flying off in different directions, forever. The longer we wait, the further away that pattern will be.
In three billion years there will be nothing alive on Earth. In 100 trillion years the last sun will be born. Spin forward far enough and only black holes will exist; further, and even they will fizz away. But wait longer, fabulously longer, and according to at least one theory of quantum mechanics, a new Big Bang will spontaneously occur.
And if not? If the ultimate fate of the universe is an eternal Heat Death, in which all is the same temperature and no work (in the technical sense) can be done; in which nothing can happen and life is impossible, as life spends entropy and there is no entropy left. Even then, look closer. Temperature is a statistical fact, an average. Subatomic particles seathe and rearrange themselves even in a dead universe. Given enough time, any pattern will -- very briefly -- appear. Ludwig Boltzmann, some hundred and thirty years ago, proposed that our observable universe could have lurched into existence as a statistical quirk. Shuffle a deck of cards for long enough and you will shuffle it into its original order; whisk an egg for long enough and you could reform the yolk.
This idea was later lampooned as the "Boltzmann Brain": that, far more likely than the whole universe appearing on the flip of a coin, is that a single brain appears, with enough time to have a single thought (the thought you are thinking right now), before it falls apart, utterly untenable that its existence is. (As a mildly terrifying thought experiment, consider that if the Heat Death is the fate of our universe, then over its history there are vastly more Bolzmann Brains than real brains, each with time for a single thought or feeling before death. By basic probability, you are more likely to be a Boltzmann Brain at the end of the universe than a human brain at its start.)
For our purposes it does not matter whether the future is an endless succession of Big Bangs, or an eternal void in which every ten-to-the-ten-to-the-fifty years or so a Boltzmann Brain appears, imagines it is reading a website, then dies. We just need something rather than nothing, and we need it forever.
A more challenging objection: my twin is not me. Derek Parfit thoroughly explored this question -- and did so by taking the transporters of Star Trek seriously. If I were transported as a beam of information to Mars, and reconstituted of new atoms there, would I be me, or merely a person who thinks he is me? Would my subjective experience be: thinking and feeling on Earth, standing on the transporter pad, then thinking and feeling on Mars; or would it be: thinking and feeling on Earth, standing on the transporter pad, then oblivion; while another entity has its own thoughts and feelings on Mars? Would the subjective line begun on Earth continue on Mars, or would it break, and a new line start there?
Imagine the line does break, that the transported me is not me, that it is not a mode of transport but of death. Why might that be?
Here we can say: there are people who have died and then been revived. Or consider: you are an astronaut, and after some catastrophe you are suddenly cooled to a fraction above zero Kelvin. You are certainly not alive. The freezing is so sudden though that when, 100 years later, your body is recovered, it is possible to reheat you with minimal damage, and bring you back to life. What would your subjective experience be? It is not difficult to believe that it is you who is revived, not merely someone who thinks they are you.
We will argue more on this later. As a sticking-plaster refutation let us ask: are the atoms different? Take two electrons. There is no means to tell them apart. All subatomic particles are, by any measure, identical.
Consider two versions of a vacation to Mars. In one, I take a rocketship; in another, I am beamed there by a transporter. Imagine that the transporter is arranged in such a way that the version of me reconstructed on Mars is identical to my state after taking a rocketship. I.e. in both situations the start and the end are identical, only the means in between differ. What happens to my subjective line in each?
In the first case, I am on Earth, I fly through space, I arrive on Mars. The me on Earth is clearly the me on Mars. There is a single, unbroken subjective line. In the second case, I am on Earth, I am transported, then an exact copy of me materialises on Mars.
Earth Mars
@ @ @
By rocketship /|\ --> /|\ --> /|\
|\ | /|
= != =
@ ### @
By transporter /|\ --> ### --> /|\
|\ ### /|
What happens to my subjective line? It is no longer certain that the me at the start is the me at the end. We consider two possibilities. In one, my subjective experience is: I am on Earth, I am dematerialized and cease to exist, then my subjective experience resumes on Mars. It does so immediately; my subjective line has no gaps. The second possibility is I am on Earth, I am dematerialized, and then: oblivion. Meanwhile, someone identical to me, who certainly believes that they are me, appears on Mars. Theirs is a new subjective line.
@ ### @
Possibility 1: /|\ --> ### --> /|\ -->
One subjective line |\ ### /|
@ ###
Possibility 2: /|\ --> ### @
Two subjective lines |\ ### /|\ -->
/|
To follow the logic of the common-sense view is to reject the second possibility. Whether I go to Mars by rocketship or transporter -- whether I am composed of the same atoms or new ones -- makes no difference to my subjective experience. To see why, imagine the converse, and try for a contradiction.
Remember, we have said that the two versions of me -- one having arrived on Mars via a rocketship, the other by transporter -- are identical. No physical test can tell them apart, even at the atomic level. But we have also argued that they are different: one's subjective line goes back to Earth, the other's began on Mars. One is me, the other is someone new, who is merely identical to me. Where is the difference kept?
In the common-sense view, there is only the physical world, and physically the two versions of me are identical. They cannot be both different (one me, the other a being who merely thinks he is me), and identical (in the sense that no physical test can tell them apart).
An objection: the two identical versions of me on Mars are, of course, different. One travelled there by rocketship, the other was transported there as a beam of information. They have different pasts, even if they are physically indistinguishable in the present. Why does the same logic not follow for whether one is and the other is not the continuation of my subjective line?
We lean on the common-sense view, and common-sensical assumptions on our continuity of consciousness, and say: in the past, the two bodies were different, the historical difference was represented by a physical difference (one body carried through space, the other beamed through it); consciousness though is a difference happening now. It is not a historical fact but a present one. Either I am or I am not conscious. That is a difference in the present, and so by our physicalist assumptions, must be reflected somehow in the present physical state.
We come to the conclusion that either the common-sense view is wrong, or matter does not matter. That it is the pattern that counts, and even if you were turned to information and reconstituted two hundred million kilometres away, it would still be you, and you in the sense that your real, subjective experience of being beamed to Mars is not oblivion, but waking up on Mars.
We began with the common-sense view. A physicalist, un-supernatural set of assumptions of what existence is. There are mysteries, to be sure. How can certain arrangements of atoms think and feel? And there is an assumption that our conscious life is finite, that our subjective experience ends and nothing follows it. We have probed this idea by considering two questions: what is it like to not yet be alive, and what is it like to be dead. Or rather: what is it like to not yet be conscious, and what is it like to never again be conscious. It is easy to answer the first question. What it is like is that you are immediately conscious. After all, there is no like until you are conscious, and no sense of time until you are conscious. To the second question, we groped towards an answer. What if the question itself is ill-formed? What if there is always a future in which you are conscious? That it will never be true that you will never again be conscious? If that were so, then the two questions collapse into one. What is it like to be dead? You are conscious again. We used the common-sense view to justify, or at least make plausible, our hypothesis. We argued that the pattern and only the pattern is important, and that any pattern will inevitably recur.
This is subjective immortality: one experience after another, forever.
We equate a person's consciousness with a physical pattern. But consciousness is, fundamentally, a phenomenon of change. To perceive a thing is to change and be changed by it.
In the Vacations to Mars thought experiment, we need the two versions of me -- the one who came by rocketship, the other who was beamed to Mars -- to be identical for the argument to work. We claim that since one version (who came by rocketship) undoubtedly continues my subjective line, the other (beamed by science fiction) must do so too, otherwise they could not be physically identical.
What, though, is this "subjective line", or "subjective continuity"? You are conscious in this moment; in the following moment you are also conscious. You anticipate future pleasures and pains because you believe that it will be you experiencing them. Belief is too weak a word here; personal continuity is fundamental to the workings of our intelligence. We plan for we are planning for ourselves.
Yet what, exactly, is being carried forward? If we remove the supernatural, we are left with atoms in patterns that change one moment to the next, and must change if any experience is to be had.
There are two useful analogies for subjective continuity and its opposite:
By nature, we see ourselves on the road, taking steps into the future. The common-sense view forces us to think in terms of the ship. The future is not a dimension we travel into; it is change that creates the future.
Recall Hume, above, "I never can catch myself at any time without a perception". In Reasons and Persons, Parfit builds a moral edifice from Hume's bundle theory of identity. Consider that we are nothing but bundles of impressions, with no unchanging core. You are just as different from a future version of yourself as you are from the present version of someone else, and have the same moral obligation to them. This raises the disturbing idea that not only might there not be subjective immortality, there might not even be subjective continuity. You might not be you one minute to the next. While you are here right now, it could be some different person looking out of your eyes next week.
(Perhaps this should not be so surprising. Over short timeframes we certainly believe in subjective continuity; over longer timeframes that is less clear. Which young person really believes that they will become old?)
Or, There is no such thing as the subjective line. A thorough contradiction of A note on continuity, above.
The common-sense view brings us to two plausible conclusions:
So we have either transience or immortality. Either there is just one experience, or if there is more than one experience, there is no justification for there not being an infinite number. While we come round to subjective immortality again, it is no longer as a form of personal continuity. Experience is, and we are not separate from it.
We are the part of the universe that is experience -- whatever, wherever and whenever that happens to be.
This site Subjective Immortality sketches the idea that a physicalist, "common-sense" view of the universe contains within it, surprisingly, the implication that we are in the only way that really matters, immortal. Subjective immortality is the term I use. It is only a sketch though, and too many objections are waved away or not even considered. And the Bundled Dichotomy, which is I think the most interesting (and original!) idea, is placed almost as an after-thought. This is what books are for.