What Makes Me, Me? (And You, You?)

While this may appear a superficially simple question, it’s actually the start of one of the most mind-bending science and philosophical journeys you can undertake, and it generally leads to a temporary existential crisis.

You have been warned…

The simplest way to answer the question that gives this essay its title is of course to simply describe yourself. I’m a man with brown eyes and brown hair and…

This is the type of rubbish that I handed to my English teacher when he asked us to write an essay on describing ourselves in secondary school, and he then held up my paper as an example of what not to do.

Nice.

However, we can start to go beyond the mere physical, as we are all aware that our physical bodies change pretty quickly as there is a significant difference between the same person at one year old, seven years old, and fifty-five years old.

Also, if I cut off your finger, you don’t lose your identity…you are still you.

So what makes you, perhaps are your thoughts, but then again these also change over time, so are you a different person than you once were?

Suddenly things become murkier.

Yes, you are biologically different than the person you were ten years ago, most of your cells will have been already replaced and you will have a different way of thinking, but there is still a link, so perhaps here we are in a type of Schoerdinger’s Cat situation where you are both the same person and also not the same person ass you once were.

Don’t worry, we are just beginning to scratch the surface of the problems of what makes you you and me me. (Yes…that sentence is also really weird.)

There are a few competing theories on what makes a particular person them, and then can be broken down into:

Body Theory – It’s your physical cellular existence that defines you.
DNA Theory – You’re just an unique sequence of DNA, nothing else. Everything that happens after birth is very much like falling down and scratching your knee, it’s incidental scar tissue. What really matters is the genetic code that describes how to make you.
Brain Theory – It’s your physical cellular existence that defines you, but not all of it, just your brain and its contents.
Data & Memory Theory – It’s not your physical cellular existence that defines you, but just the information and memories that are stored in your brain.
Continuation Theory – The idea that it’s your continuous subjective experiences that define who you are through time, not your body, brain, or even just the data in your head.
Soul Theory – The idea that we have souls that are somewhere inside of us and give us “life”. Yeah…

What I will show in this essay is that none of these theories can actually stand up to scrutiny, and then attempt to build the beginnings of a meta theory (A theory of theories) that actually can describe what makes you, you.

The core reason why none of theories offer a comprehensive definition of a person’s identity is because they are built upon assumptions that can actually be quite easily disproved by points that are raised in one of the other theories.

But before we dive right into the theories of what makes you you and me me, we should ask ourselves what’s the difference between being alive and being dead, or even just being and…not being.

After all, the material that you’re made out of has been around since the beginning of time.

Let’s explore this.

Antonie Lavoisier discovered the Law of Conservation of Mass in 1785 which essentially stated:

Matter is neither created nor destroyed.

Jump forward about sixty years, and Julius Robert Mayer discovered the Law of Conservation of Energy (now called the First Law of Thermodynamics) in 1842, which, in brief, states:

Energy is neither created nor destroyed.

Jump forward another 60 odd years (apparently this is what it takes for this kinda stuff to sink in and for the next guy to make the next leap) and in 1905 the now-famous Albert Einstein announced his famous E = mc2 and as a consequence, the two laws were merged into the Law of Conservation of Mass-Energy

The total amount of mass and energy in the universe is constant and can interconvert.

So all the material that you are made out of has always existed either as mass or energy, and yet it is only in its current combination that suddenly “you” come into the picture as an individual.

That’s quite strange, huh?

Life vs Stuff

So the first question we need to tackle is whether there is a fundamental difference between life and just “stuff”, like a rock.

Just like the first question we asked (What Makes Me, Me?), this also appears stupidly simple, and yet the smartest people in the world both now and across history have been baffled about this, because there is no easy way to draw the line between dead stuff and alive stuff.

I mean, deep down, I feel that I know that there is a difference between me and a rock, but how do I prove it?

The scary thought about there being little or no difference is that perhaps life is even more meaningless than we may first think because we may be no different to a rock.

The textbooks tell us that to be defined as alive, you need to do the following, which can be handily remember with the acronym MRS GREN:

Movement – The ability for an organism to move all or some of its organic parts. Some organism don’t appear to be able to move at all, but they will have some movement ability.
Respiration – The ability to convert matter around you into energy. Most organism are built around the breakdown of sugars with the use of oxygen, but some microorganisms use other molecules such as nitrates and iron to help break down sugars.
Sensitivity – Essentially, being able to detect some changes in their environment and then act accordingly. Like a rabbit being able to see a fox and run away.
Growth – An irreversible change in mass. So organism can get larger, but they cannot reduce that mass.
Reproduce – Creating further organism from themselves.
Excretion – The removal of the waste by-products of respiration.
Nutrition – The taking in of nutrients and food to power respiration. This can be in the form of eating other animals, as well as just breathing, or even taking energy from the sun via photosynthesis, the way plants do.

The above also means that you need to be subject to the theory of evolution, and so we can add “Evolution” to the mix, and also the idea of control inside their bodies (to maintain certain conditions of chemicals, temperature, and so on) so we can reach a much nicer acronym of MRS C GREEN:

Movement
Respiration
Sensitivity
Control (Homeostatis)
Growth
Reproduce
Evolve (over generations)
Excretion
Nutrition

Erwin Schrödinger, the Austrian physicist who famously gave us the Schrödinger’s Cat thought experiment, defined life as:

Living things avoid decay into disorder and equilibrium.

Which is an interesting way of looking at things. So life takes the random accumulation of matter that already exists in the universe and gives it order.

Every living thing is made up of cells, which in themselves can also be considered living things as they meet all the above criteria. They have a cell wall which brings order compared to the outside world, and they can take in nutrition and excrete, they can reproduce, and they can evolve, and so on.

So far, so good…but there is a problem.

Cells are made of atoms, and atoms are not alive.

So, you’re a pile of around 7×10^27 (seven followed by 27 zeros or seven billion billion billion!) non-living things (atoms) , made up of 37.2 Trillion (actually anywhere between 15 Trillion and 70 Trillion depending on who you ask ) living things (cells) that are collaborating to create one big living thing:

YOU.

That feeling at the back of your head right now is your brain trying to process this.

So this is the equivalent of going to Australia during camel-culling season (yes, they do have a camel problem, strangely enough there are around 1 million feral camels in Australia that were imported from British India and Afghanistan during the 19th century for transport and construction…who knew!) and shooting a bunch of camels and throwing them down into a canyon, and then going back the next day to find that they have all turned into a giant sky-scraper sized camel, that’s alive.

Actually, it’s even more complicated and mind-boggling than this.

So cells, like everything else, are made up of atoms, but there are things that are bigger than atoms but smaller than cells, which cells are made up of. Things like amino acids and proteins. These combine with each other to form reactions which start other reactions, which start other reactions, and so on.

Several hundred million to more than a billion of these reactions are happening in each of your cells, in any given second.

So essentially, you’re made up of a vast number of chemical reactions, something in the order of:

37,000,000,000,000,000,000,000 chemical reactions PER SECOND.

And this is all from the food and air that we eat and breathe, and so we are like a car that is driving down the road and being constantly rebuilt based on what we find on the road.

So the definition of “I” becomes very fleeting, in the same way that we name a river, but the water that flows through that river only flows through it once and it is different every time. This is actually the basis for a concept called Four-Dimensionality which we will discuss a little later.

However, let’s remember than no individual small part of you is actually alive, it is all dead matter that respects the laws of the universe.

So is life just the sum of lots of chemical processes? That doesn’t feel very special, and that would mean that death is, well, not much, as chemical process would continue in your body even after you die.

However, perhaps we can find salvation in the fact that every living things has DNA, essentially genetic instructions on how to build “you”.

Ok, so that nows starts to feel like we are onto something, something unique. After all, life is a bunch of stuff that carries genetic information around.

I won’t bore you with the theory of evolution, but essentially the grand goal of living is to pass on your DNA (normally via offspring) so your species survives, and so perhaps DNA itself is life?

Nope, sorry.

It’s a very complex molecule, but it doesn’t stand up to our MRS GRE(E)N rule from earlier on.

It’s alright, things are about to get significantly more head scratching.

Let’s consider viruses, like the type that make the rounds each winter and give everyone a few days or weeks of bad throats and runny noses.

Initially, because they could spread from person to person, we believed that viruses were one of the simplest of all life forms. However, with further study this was shown to be false.

In 1935, Wendell M. Stanley and colleagues crystalized a virus they saw it was far more similar to a chemistry set for life than life itself. Essentially a virus is a package of complex biochemicals, but lacks the essential system that are required for metabolic functions, which is the things that kinda makes life, well, life.

When a virus enters a cell, however, then things get interesting. It is able to control the cell’s own replication machinery to reproduce itself, which can then go and infect more cells.

So viruses are in some ways on the border between alive stuff and dead stuff.

So, to answer our question, what’s the difference between living things and stuff, I believe that Schrödinger’s definition along with MRS GRE(E)N is good enough for us today:

Living things avoid decay into disorder and equilibrium.

So, let’s explore the different theories of what actually defines you.

The Body Theory

Sam Harris in his book “Waking Up: Searching for Spirituality Without Religion” gives this poignant thought:

What makes me the same person I was five minutes ago, or yesterday, or on my eighteenth birthday? Is it that I remember being those former selves and my memories are (somewhat) accurate? In fact, I’ve forgotten most of what has happened to me over the course of my life, and my body has been gradually changing all the while. It is enough to say that I am physically continues with my former selves because most of the cells in my body are the same as or descended from those that made up the bodies of these younger men?

This is an incredibly interesting train of thought, and building the idea and concept of “you” over time is not something that is easy to do, as we shall see.

The body and everything in it is where we started at the beginning of this essay. It is that traditional concept of “I” – everything that’s in my body. That’s the reaction that most people have when asked to explain who they are, and initially it appears to be a valid one. After all, if I place your body into a box, you are definitely in a box.

Also, when someone isn’t feeling well or has some time of psychotic behaviour, we might say that he “isn’t himself”, but we definitely don’t mean that it is not actually him.

However, this theory doesn’t hold water if we poke holes in it.

If I cut your fingernails, you are still you, regardless that your fingernail are now on a journey down your sink and into the sewage.

If you lose a finger in a work accident, you are still you, there is no debate of whether your now severed finger should be given voting rights or whether your family won’t recognize you when you get back home.

In fact, even if we replace many of your internal organs with synthetic replacements or even other people’s (hopefully donated) organs, nobody in their right mind would claim that you are a different person.

In fact, our cells are constantly changing and replacing themselves, and it takes about seven to ten years to be a completely “new” person.

We can take all this a step further and imagine that we could replace your atoms one by one with different atoms, all while keeping you alive and consciously awake. At what stage would one say that you’re a different person? One atom changing obviously would not quality, but what about 50% of your atoms, or 99%? And at the exact moment when we define the change, if we change one less atom, are you suddenly still the same person, so is there only a one atom difference between who you once were and who you then became?

So, it appears that we value far more what’s going on inside of heads than what is happening around the rest of our bodies, and so it’s time to move our investigation to the brain as this theory isn’t looking so good.

But before we do that, let’s take a minute and quickly displace one common body theory argument, and that’s the argument of DNA being “you”.

The only problem here is that identical twins have the same DNA and are clearly not the same person, and if/when in the future we are able to clone human beings, then obviously the clone will not be the same person as the original, because the actual information stored in their brains will be different, and so they will merely be a copy.

The Brain Theory

So if body isn’t looking so good, perhaps it’s the brain, you know, where all the thinking and you-ness goes on.

After all, if we could somehow extract the brain and place it in a vat and ensure it received all the oxygenated blood and anything else it requires, and hooked up the nerve endings to a computer that could decipher your thoughts, we would probably say that this is now “you”, as that is who we would be communicating with.

You would certainly hold that opinion! If you were asked to choose between two options:

We shoot and burn your old brainless body.
We permanently shut down the computer that is currently powering your brain.

You would probably feel that we would be killing you if we turned off the computer, not if we burned your now-brainless body.

In fact, we can take this even further and imagine if brain transplant were possible, we could switch your brain with Donald Trump’s and you would wake up in each other’s bodies. To wake up in another person’s body it would for sure be a “Holy Shit” moment, but that would definitely be you, and you would be sure of it. In fact, this is more like a body transplant than a brain transplant, as “you” are keeping ownership of the same brain the whole time.

Ok, so this theory is looking much stronger than the body theory, but here comes the kicker:

What if we were to somehow upload your consciousness to a computer, and then complete destroy your body and brain, but your consciousness was still up and running on the computer, and we could communicate with it…then what?

Or what if instead of the doing the above body transplant, we did a true brain transplant, where we deleted Donald Trump’s consciousness, and then injected your consciousness into Donald Trump’s brain, so when you wake up you’re in the same “Holy Shit” situation that you were a few paragraphs up, but this time you’re using someone else’ brain instead of your own?

So, now it looks like the brain theory isn’t so smart after all, as there can still be a “you” without your brain, it just happens to be the case right now that the brain is the only processing machine available that can power your own memories, experiences, and general consciousness.

The Data Theory

However, not all is lost. The conclusion and debunking of the previous theory give us a strong push into the right direction, perhaps it is all just about memories and experiences and general consciousness. Essentially, all the data which is stored in your brain is what makes “you”.

In Homo Deus, a brilliant book that I highly recommend you read, there is a thoughtful question posed about whether humans beings can be reduce to algorithms. As the computerization of entire industries is now taking place, this looks more and more likely to be true, which essentially means that our brains are incredibly sophisticated calculators. However, algorithms do not care if the underlining system is organic-based or silicon-based, or anything else for that matter. Which means, we may well in the future be able to transplant all our data, our memories, our values, all our thoughts and biases, everything that makes “us”, into a machine, and essentially make a digital copy of ourselves.

As an aside, this leads us to a very fundamental problem. If we can be boiled down to just data and information on how to process new data (algorithms), and at our very core we are just the sum of 37,000,000,000,000,000,000,000 chemical reactions per second, then perhaps we are not much more than chemical reactions? Perhaps what we believe to make us special, to give us “life”, things like consciousness and free will are not at all special, but just the results of lots of amino acids and proteins interacting in completely standard ways that can be pre-mapped? Perhaps we’re much different than a rock.

Coming back to the data theory, there are problems also here:

What happens if you lose your data? To you stop being you?
How much of this data is required for you to claim to be you?
What happens if we can replicate this data? Like in the example above when we transferred your data, what would happened if we copied it instead?

Losing Data

If you’re 35 and you fall over and hit your head and you forget everything that happened before you were 12, you don’t have to go and try and get a new passport: you are still you.

In fact, memories are hardly a stable and trustworthy source of data, it has been proven that they are constantly revised and edited based on new information and the amount of times that these memories are accessed.

This is quite a personal issue to me because my father died of Front-Lobal Dementia, which is a disease that essentially has the same effects as Alzheimer’s Disease, in which the person slowly loses all memories, then motor function, then consciousness, and eventually also bodily function, which leads to death. This can take anywhere between two to ten years, and it’s not a pleasant experience for the afflicted person or their close family and friends.

However, even near the end, I was told that there were still sparks of recognition here and there when certain close family members sat close by. It may have been the smell of their clothes, the timbre of their voices, or simply the touch of their hands. So if that was still being recognized, but all the data and memories were either almost completely gone or inaccessible, was my dad still my dad, or was he already dead, and his body lived on?

At the time, when I was thinking about this, I reached the conclusion that he essentially had two deaths, his consciousness died before his body did, and it was far more tragic when his consciousness died than when his body did, because the second death had little impact compared to the first. It was more of a confirmation of what had already happened.

The “How Much” Problem

Coming back to a less tragic framework, we all actually forget much of what happens day to day in our lives. In fact, I’ve often wondered what the point of my copious amounts of reading is when I forget 90% of the detailed arguments of all the books I read, and in fact much of what I also write as well. The answer to this question is that while you make forget the precise data, everything that happens in your life shapes you and builds specific mental models that allow you to live the remainder of your live in a slightly different (and hopefully better) way.

However, just because you can’t remember what happen exactly seven years ago on March 25th, doesn’t mean that you didn’t exist on that day.

In fact, what’s an acceptable amount of detail to remember in your life? 10%? 1%? 0.001%?

And if were to copy your data elsewhere, would we even need an accurate representation of all your memories and mental models, or what a “just enough” attitude work, and would we still be able to claim that this was legitimately you?

In other words, where do you draw the line?

The Replication Problem

So jump to the far future where humankind has already invited a ton of really cool shit, including teleportation, and the way it works is this:

You go into the teleportation departure room.
You get scanned by some funky lasers that record the position of every single atom in your body (all seven billion billion billion of them!).
You then get destroyed be said laser in the teleportation departure room. This is quick and painless (at least!)
About 5 minutes later in the teleportation arrival room on the other side of the world, other funky lasers are busy reconstructing every single atom of your body based on the record, and you walk out of the door of the room with only a small flash in your consciousness. This has a 100% success rate, and nobody has ever been actually killed because of a malfunction.

Let’s not delve into how cool this would be, or the incredible changes in society that would happen if this technology existed, but let’s stick to the high level view:

If you take this trip to work and back five times a week, you are essentially dying ten times a week, and having a replica of yourself made each time, and nobody notices anything.

This is all good and well, but what happens if there is a malfunction in the teleportation machine, and the lasers that should destroy the original you don’t work, and suddenly there are two of you, one in your home city where should have departed (probably somewhere with great weather and a beach?) , and one whether your work city (some rainy suburb in London?).

Now there are two exact version of you walking around in the world, with exactly the same body, brain, and consciousness. Yes, the one at the arrival room is made from different atoms, but then again the atoms in your body are constantly changing as you eat food and expire and excrete, and there is probably very little cellular material left of you from ten years ago, and yet you are still the same “you”, and even the law recognizes you as such.

What would happen in this above scenario is that you would be dragged off kicking and screaming into another chamber to be destroyed, and it is strange that just because of a timing issue, your original you would feel entitled to live and would consider the London you to be an impostor, when that is the same journey that you take each and every day to work. While society would surely be able to build a legal framework around this somehow, it is difficult to reconcile the fact that in a malfunction like the one above it should be the original “you” to die, and not the replica, even if it does make perfect sense.

So, clearly, data alone does not make a great definition of “you” as that data could be partially or wholly corrupted and we would still consider you to be you, or we could copy it to somewhere else and there would then be multiple you(s?).

Of course, one fallback for the second issue, the replication issue, is that the original you is always you, but what if we clone your data into both Donald Trumps already-cleared brain as well as Donald Trump’s son’s brain, and then shoot you.

Now we have no original you, but both Donald Trump and Donald Trump’s son that truly believe that they are you, and they have all your data and memories.

Ok, I’m going to stop here on this, it’s making my brain hurt…but clearly the data theory has a few holes in it, but there…

Ok fuck it, let’s continue and destroy this data theory.

The Continuation Theory

So, now that we can be pretty sure that the data in your head is alone not enough to make “you”, we may then move onto the next argument, which is called the Continuation Theory.

This is the idea of four dimensionality, that you’re not just what you are right now in three dimensions…the sum of your body and everything in it, but the sum of all four dimensions, the sum of your body and everything in it, since the beginning of when you were born (or earlier than that, if you care to be picky.)

This idea of four dimensionality also gives a punch in the face to the data theory because the obvious conclusion is that we’re not just the current state of data in your brain right now, but all the operations that have happened to that data ever since it has been there. Remember the data, changing it, deleting it, updating it, and so on.

I recently had a discussion with my brother about how disgusting Bulletproof coffee is, and we tried it when we were in New York around eight months ago at the time of writing, and he remembers that the person who served us at the coffee shop was a typical hipster guy with a shaved head and a mustache and tattoos, while I remember that it was a hot black girl in her twenties who was a bit grumpy and didn’t talk much or smile at us. It’s strange how from exactly the same experience we both remember completely different things, and I wonder who is right, if anyone? (We could be both mistaken).

We’ve discussed many times before how the entire world is made up of stories, and the intricate web of stories that we have now are the primary reasons that large number of humans can collaborate together to create complex societies that are able to unlock some of the mysteries of the universe.

So perhaps, that is the key to identity, it is an unbroken story that is told by both yourself and others about who you are, and even if the story progresses and the characters and details change over time, it is still the same story.

I feel that we are really getting into something good here, and of course it is now worth bringing up The Ship of Thesus, also known as Thesus’s Paradox. This paradox was famously written by Plutarch in “Life of Thesus” in the late first century. The basic premise was to ask whether a ship that has been restored by changing every single part still remained the same ship? Let’s quote directly from the original, albeit translated, text.

The ship wherein Theseus and the youth of Athens returned from Crete had thirty oars, and was preserved by the Athenians down even to the time of Demetrius Phalereus, for they took away the old planks as they decayed, putting in new and stronger timber in their places, in so much that this ship became a standing example among the philosophers, for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same.

If you think about this, this has a large implication of whether we can identify with our younger selves. Consider that every single cell in your body will die and be replaced within roughly a ten year period, you then have to wonder what it is that you have in common with your younger self. As we have seen, your ideas, the synaptic connections between the neurons in your brain, have also changed over time as your database is constantly being updated and changed.

And so, all we are left with is the fact that you at 55 are, in part, similar to your slightly younger self at 50, but not completely, and you at 50 are similar to your slightly younger self at 45, who has very little to do with you at 55, but is relatable to you at 50, and that is how we reach the point where a 78 year old can look at a picture of a six year old and say, “that was me”.

A really big mind-fuck issue with the Ship of Thesus, regardless of your opinion of the paradox, is what happens is if you do the following:

Imagine that has you replace each part of the ship, you keep the old parts and build another ship with all the old parts of Thesus’s ship, so eventually you end up with two ships:

The ship that is still being used by Thesus on a day to day basis, but has had each part replaced by new parts.
The ship that you sneakily built on the side, that contains every single original part of the ship of Thesus, but is not currently used by Thesus.

Which is the real Ship of Thesus?

One could argue that it is the first ship if this restoration was done during Thesus’s lifetime, but if the ship is in a museum and being restored after it has stopped being used, then perhaps the second ship is actually the original ship.

Nobody said this was going to be easy.

Left vs Right Brain

Of course, this continuation theory was so lovely, and it really looked promising, so here we are now, back again at destroying this theory.

As I am sure that you are aware, the brain is split into two parts, conveniently called the left brain and the right brain, I’ll let you guess where these are.

The way to body is wired means that each half of the body is controlled by the opposite side of your brain. So, for example, your left side of the body in controlled by the right brain, even to the point that what you see from your left eye is fed into the right brain.

The two brains are connected by a thick nerve cord that allows communication between them, and (yes, that was a plural on the word brain, and it is just about to get ridiculous important for what we are talking about) they do some ridiculous fancy real time maths and calculations to make it appear to your conscious vision that all is one. It’s actually crazy impressive when you think about it.

So, in normal life, this is all good and you live, you pay your taxes, and then you die.

Big deal.

However, there have been times when for medical reasons it has been necessary to cut the nerve cord that connects the two half-brains, as this stops repetitive epileptic seizures from spreading across the entire brain… which is a good thing.

When this operation is carried out, the patient is actually fully conscious, and this is often done in brain surgery to ensure that the surgeons are not doing anything they shouldn’t be doing as the patient should be able to count and speak normally.

After the operation, the patients can then live out the rest of their lives quite normally, but there are sometimes strange side effects such as one hand wanting to open a door and other slamming it shut, which caused experts to study further what happens when you cut this communication cord between the two half-brains, and what they discovered was absolutely amazing.

Essentially, there are two centers of consciousness inside your head, and when you cut the communication cord between them, it is like you’re splitting into two people while the entire time you are conscious and don’t notice a thing.

There are some incredible and interesting experiments that have been made on people that have had this operation, and that they have shown without doubt that there are two centers of consciousness, but before we get into that, it’s worth looking at the differences between the two sides of the brain.

The left hand side of the brain, sometimes called the digital brain, is the part that is more adept at:

logic
sequencing
linear thinking
mathematics
facts
thinking in words

While the right hand side of the brain, sometimes called the analog brain, is the part that is more adept at:

imagination
holistic thinking
intuition
arts
rhythm
nonverbal cues
feelings visualization
daydreaming

Of course, for many tasks we require both parts of the brain working in conjunction, and this is where things get interesting when the communication between the brains is split.

The experiments normally go something along these lines.

You show something to one half of the brain.
You ask a question about that object to the other half of the brain.

So, for instance, we might show the left eye (the right brain) the word egg, and then ask the right hand (left brain) to pick any object the wish from behind a curtain, and it will pick the egg. We can then ask for a verval response (left brain) about why the eggs was the object picked, and the left brain will make up a convincing story about why it chose to pick the egg, that will have nothing to do with the fact that the word “egg’ was shown to the right brain.

Strange, huh?

Time Travel

Time travel to the past is something that many scientists believes is theoretically possible, and it is interesting to play with the idea of what would happen to personal identity if we managed to go back in time and meet ourselves.

Many believe that this would cause a paradox, because going back in time to meet yourself may well alter your past, which means you would not be able to go back in time to meet yourself, which then means your past self could now live your original timeline and so now you are able to go back in time, but then that means you may alter your past…and now we’re in a time-loop or a paradox.

That aside, there was what I found a rather humorous example in Patrick Bailey’s Thesis “Concerning theories of personal identity.”, which I showcase below:

Suppose that Michael Ellis builds himself a time machine. Being a rather conservative fellow, he decides that his initial test of the device should not be overly extravagant. Let us suppose that he sets his first leap through time for ten minutes into the past. Checking both his watch and the wall clock in his lab, he finds that both read 2:30 pm. He steps into the machine, configures the appropriate settings, and braces himself in his seat.

After a brief jolting of the machine, Michael Ellis opens the door and steps out to find himself still inside his lab. Immediately, he checks the time on his watch
against the wall clock. The wall clock reads 2:20pm. The leap was successful. As Mr. Ellis peers around the lab, he spies a man performing advanced calculations on a chalkboard hanging on the back wall. He approaches the man at the chalkboard, taps him on the shoulder, and speaks.

“I thought I might find you here. As you can see, our time machine works,” stated Ellis. “It’s ok, don’t be alarmed. We’re the same person. I just jumped backwards in time by ten minutes,” he assured his counterpart.

“How can we be the same person – we’re in separate points of space?” asked Ellis-2.

“That’s a good question. Considering that my body wasn’t destroyed, as might happen through teleportation, I should have 100 percent bodily continuity with you, yet we both occupy different points in space,” continued Ellis, “and the same should be true for my psychological continuity. At no point has my psychological continuity been broken with yours.”

“But there is a difference – my bodily and psychological continuity will always be ten minutes behind yours. The clock now reads 2:21. Your watch should read 2:31. So in approximately ten minutes my state of continuity will be identical with yours as it is now,” claimed Ellis-2.

“So, we’re different persons?” asked Ellis.

“Well, how can I be identical with you if I haven’t had all of your current experiences?” asked Ellis-2.

Ellis replied, “You seem to have a good point there. I appear to have all of your experiences, but you lack those that I’ve had for the past eleven minutes.”

“Well, not exactly,” said Ellis-2. “What do you mean?” asked Ellis.

“You don’t have all of my experiences. By being the first to make the leap backwards, you’re missing the experiences I’m having right now by interacting with you,” Ellis-2 explained.

Ellis was baffled. “But I should have the experiences you’re now having in another ten minutes, after you’ve gone into the time machine and are then standing here speaking these same words I’m speaking to you now. Yet, I think there’s another difficulty,” Ellis stated.

“What’s that?” asked Ellis-2.

“Would you say that we both possess free will?” asked Ellis.

“Of course we do,” confirmed Ellis-2.

“Then couldn’t you opt not to enter the time machine at all? And couldn’t I
opt to leave the room, so that I didn’t experience your interactions with me as you do now, if you did decide to leap?” questioned Ellis. “If not,” continued Ellis, “then how can we claim to have free will? Are our actions determined for us?”

“I’m not sure,” said Ellis-2, “If I don’t make the leap, then it seems to create a paradox, in that you shouldn’t be here now talking to me. But if I can’t make the decision not to leap, then, apparently, my actions are already determined for me.”
Both were baffled by the situation. “If you do, in fact, have free will – as we generally suppose of all persons – and you choose not to enter the time machine, would that pose a threat to me? Would I simply vanish, since I should not have jumped, had you not made the decision to do so?”

“It’s hard to know what to say about that,” admitted Ellis-2.
“I agree,” said Ellis. “The problem appears to include that my actions affect your timeline, if we are genuinely the same person. That is, if I refuse to make the leap backwards, then, being identical, you should not have been able to do so,” claimed Ellis-2.

The clock on the wall now read 2:25. “There seems to be two essential questions we’re asking here,” stated Ellis, “the first being that we are either identical persons, or we are instead exactly similar beings. If your actions affect my present timeline, then we must somehow be identical or, at the very least, causally linked in a way that implies identity. To say that we are merely exactly similar implies that, while similar in every respect, we are not causally linked and therefore your actions should have no bearing on my timeline. The second question asks whether we have free will, allowing us to choose the course of our own actions, or whether our actions are determined for us.”

“And we could very well complicate things all the more by both entering the time machine together,” said Ellis-2, “and in doing so wind up with three individual bodies here, after the leap: you and I – the two time travelers – and the unsuspecting gent who will then assume my role in the lab, during this scene. What do you make of this?”

They both looked at the wall clock – 2:27. “I’m not sure,” stated Ellis, “but it looks as if there are a number of ways we could continue to complicate our situation, if we have free will. Continually adding our numbers to our time-traveling group, as you’ve just indicated, is a perfect example. It seems we could infinitely duplicate ourselves this way, all the while being psychologically and bodily connected to each other, without ever destroying our bodies and with no visible point of fission.”

The clock read 2:29. “What do you think will happen?” asked Ellis-2.

“I don’t know, but I have a feeling we’re about to find out any minute now,” replied Ellis.

The Soul Theory

Another interesting theory, and in fact perhaps one of the most popular ones, is the idea that that humans have an everlasting soul, and that is what animates us and, essentially, makes us “alive” and “us”.

Christianity is one of the main systems that promotes this belief and, in some ways, it is a shame that is has become so widespread and it is a serious impediment to a concrete understanding of the human mind and a strong definition of “you”, because it allows an easy and simple solution to all the problems mentioned above.

It’s a little bit like how in the Middle Ages in Europe we entered into a scientific and technological dark age because, for example, all you had to know about why it rained was because it was God’s will, and why try and question God’s will and look for deeper answers?

However, after all the disproving of the above theories, including the continuation theory which felt like it may have been our best bet, perhaps it is time to seriously look at the question of whether humans do have a special spark?

In some ways, society is already in acceptance that humans are special, and this is where things become difficult even for the most ardent scientific mind. After all, why is regarded as wrong to have human soup, but absolutely find to have chicken soup? Clearly, we believe there is something different between humans and animals, and that humans are special. I’ve discussed this at length both in my essay on why I am vegetarian, and also in the book summary of Homo Deus (and I highly recommend you go and read the entire full version of the book as well).

The key problem with believing in the Soul Theory is that it is not compatible with the view that humans are part of the evolutionary process that has underpinned life for several billion years and, frankly, if we are willing to throw the theory of evolution out of the window, then there isn’t much point having a sensible debate about anything.

Yuval Harari does a great job of explaining this in Homo Deus:

The literal meaning of the word ‘individual’ is ‘something that cannot be divided’. That I am an ‘in-dividual’ implies that my true self is a holistic entity rather than an assemblage of separate parts. This indivisible essence allegedly endures from one moment to the next without losing or absorbing anything. My body and brain undergo a constant process of change, as neurons fire, hormones flow and muscles contract. My personality, wishes and relationships never stand still, and may be completely transformed over years and decades. But underneath it all I remain the same person from birth to death – and hopefully beyond death as well.
Unfortunately, the theory of evolution rejects the idea that my true self is some indivisible, immutable and potentially eternal essence. According to the theory of evolution, all biological entities – from elephants and oak trees to cells and DNA molecules – are composed of smaller and simpler parts that ceaselessly combine and separate. Elephants and cells have evolved gradually, as a result of new combinations and splits. Something that cannot be divided or changed cannot have come into existence through natural selection.
The human eye, for example, is an extremely complex system made of numerous smaller parts such as the lens, the cornea and the retina. The eye did not pop out of nowhere complete with all these components. Rather, it evolved step by tiny step through millions of years. Our eye is very similar to the eye of Homo erectus, who lived 1 million years ago. It is somewhat less similar to the eye of Australopithecus, who lived 5 million years ago. It is very different from the eye of Dryolestes, who lived 150 million years ago. And it seems to have nothing in common with the unicellular organisms that inhabited our planet hundreds of millions of years ago.
Yet even unicellular organisms have tiny organelles that enable the microorganism to distinguish light from darkness, and move towards one or the other. The path leading from such archaic sensors to the human eye is long and winding, but if you have hundreds of millions of years to spare, you can certainly cover the entire path, step by step. You can do that because the eye is composed of many different parts. If every few generations a small mutation slightly changes one of these parts – say, the cornea becomes a bit more curved – after millions of generations these changes can result in a human eye. If the eye were a holistic entity, devoid of any parts, it could never have evolved by natural selection.
That’s why the theory of evolution cannot accept the idea of souls, at least if by ‘soul’ we mean something indivisible, immutable and potentially eternal. Such an entity cannot possibly result from a step-by-step evolution. Natural selection could produce a human eye, because the eye has parts. But the soul has no parts. If the Sapiens soul evolved step by step from the Erectus soul, what exactly were these steps? Is there some part of the soul that is more developed in Sapiens than in Erectus? But the soul has no parts.
You might argue that human souls did not evolve, but appeared one bright day in the fullness of their glory. But when exactly was that bright day? When we look closely at the evolution of humankind, it is embarrassingly difficult to find it. Every human that ever existed came into being as a result of male sperm inseminating a female egg. Think of the first baby to possess a soul. That baby was very similar to her mother and father, except that she had a soul and they didn’t. Our biological knowledge can certainly explain the birth of a baby whose cornea was a bit more curved than her parents’ corneas. A slight mutation in a single gene can account for that. But biology cannot explain the birth of a baby possessing an eternal soul from parents who did not have even a shred of a soul. Is a single mutation, or even several mutations, enough to give an animal an essence secure against all changes, including even death?
Hence the existence of souls cannot be squared with the theory of evolution. Evolution means change, and is incapable of producing everlasting entities. From an evolutionary perspective, the closest thing we have to a human essence is our DNA, and the DNA molecule is the vehicle of mutation rather than the seat of eternity. This terrifies large numbers of people, who prefer to reject the theory of evolution rather than give up their souls.

The Meta Theory of Personal Identity

So, to develop a meta theory of personal identity we first need to have a clear understanding of what “identity” really is.

The funny thing about identity, as we have discovered above, is that it is notoriously difficult to pin down, and yet in practical terms, nothing could be more obvious to ourselves that we are the same individual person we were ten minutes ago, as well as ten years ago.

Identity, in a nutshell, is essentially the relationship that a things has to itself, compared to the relationship that is has to other objects. So, identity is what makes something what it is, and separates it and makes it distinguishable from all other things.

So when we say “personal identity”, we mean the total of everything that a thing must have to be considered a person, and then the uniqueness of those factors that specifically mean that this person is you, and not me.

So, for instance, we may define a person as someone that must have feet (this would be wrong, of course, as some people do not posses feet). So we then look to see if you have feet, and we then describe how your feet are different to other people’s feet, and that is how we know that you are you, and not me.

Unlike the definition of what it is to be alive instead of just stuff, with can be remembered with the acronymic “MRS GREN”…

Movement – The ability for an organism to move all or some of its organic parts. Some organism don’t appear to be able to move at all, but they will have some movement ability.
Respiration – The ability to convert matter around you into energy. Most organism are built around the breakdown of sugars with the use of oxygen, but some microorganisms use other molecules such as nitrates and iron to help break down sugars.
Sensitivity – Essentially, being able to detect some changes in their environment and then act accordingly. Like a rabbit being able to see a fox and run away.
Growth – An irreversible change in mass. So organism can get larger, but they cannot reduce that mass.
Reproduce – Creating further organism from themselves.
Excretion – The removal of the waste by-products of respiration.
Nutrition – The taking in of nutrients and food to power respiration. This can be in the form of eating other animals, as well as just breathing, or even taking energy from the sun via photosynthesis, the way plants do.

…the meta theory of personal identity does not require every box to be checked. For something to be characterized as alive, it needs the potential to do all of the above, while in our meta theory of person identity we simply ask that for a person to be considered that person, they need to exhibit at least some of the rulesets examined in the various theories we covered (with the exception of the Soul Theory).

The strongest argument that I have come across is that personal identity is actually not what matters, which spins the entire argument into a completely different path, but not a bad one.

Essentially, as soon as “you” can be identified as a unique individual with any of the above theories, then all that matters in terms of identifying that you are actually the same person from five minutes or ten years ago, is survival.

Did the historical “you”, however we wish to define it, survive to be the present you?

That’s the question we need to answer, and we will then see that it doesn’t really matter if your data has been moved onto a computer, if you’ve been terminated and rebuilt inside a teleportation device, if you have time travel travelled or completely lost all your memories of your life up to this present moment.

You have, in one way or another, survived, and that’s what makes you unique, and not a rock.

Enjoy thinking through this one.