How do I know that the subject of my memories and me are the same person?

I have a memory of waking up this morning. How do I know that the subject who woke up and the subject remembering it are the same person?

  • 2
    I will wager that you have given this question some thought. Can you share your thinking to start the analysis? Dec 21, 2017 at 2:51

6 Answers 6


Your question points to the subjective assessment of existence.

Common similar questions (in order of level of subjectivity) are:

  • Since a river changes every second, how do you know this is the same river as the one you saw 1 second ago?
  • Since a rainbow changes position depending on the point of view, how do I know that the rainbow I'm looking is the same that you are looking?
  • since atoms are permanently exchanged with the environment, and atoms move, change positions, how do you know that the pencil in your hand is the same pencil along time?

The answer is that they are never the same. Everything changes permanently in the universe, there are no boundaries between things, mass is just interaction. The fuzzy nature is completely different to the universe of things you experience. Things are a product of your mind (and your body, to a certain extent). So, the person you are dreaming of, don't exist anymore.

But our mind has the amazing capability of defining boundaries between atoms, approach them as complete and isolated entities, and use them to think. We don't have yet a minimum of understanding of how our minds can do such task.

Then, the person you are dreaming of exists into your ideas, and that's enough for you to keep you surviving. If you feel it's the same, it's the same. If you feel there are differences with reality, well, it's you that will decide if such person is the same.

Since we are a child, we get the approach of understanding things (for example a coffee stain) as if they would be immutable, permanent and persistent, even if they are not. So, it's your mind that is telling you that the person on the other side is you yourself, while you can see your image.

  • Fundamental particles lack identity, and it is a provable property of them that they can be swapped without change, are directly equivalent. Seems like it's just thermodynamic irreversibility we turn to
    – CriglCragl
    Apr 28, 2018 at 11:12

If 'memory' is used veridically, as it usually is, so that a memory is necessarily a true recollection, then if you now have a memory of waking up this morning, it must be you now who woke up this morning or it wouldn't be a memory. Memory is the recall of what actually happened. You could have a false memory of waking up this morning, but that's not a memory, or you could have an apparent memory, but that's also not a memory. It's part of the logic of memory in this sense that if it wasn't you now who woke up this morning you couldn't remember doing so. You could of course think that you remember waking up this morning when in fact you can't, because you are not the person who woke up : but you couldn't actually remember unless you are that person.

But the problem you pose is real. I've made a logical point but you raise an epistemological problem. You have no way of telling the difference between a veridical, actual memory and a merely apparent or false memory. Phenomenologically, as you experience them, they are the same. There is no criterion by which you can distinguish veridical, true memories from spurious ones, from within your own experience.

It might indeed be the case that a succession of instantaneous selves has passed in and out of existence between this morning and now, each preserving a part of the previous self's mental content. Within that content might be the thought that you woke up this morning. That would explain why you now think that you woke up this morning when in fact it was the self at the start of the instantaneous series that actually woke up.

I can't turn or deflect your sceptical challenge. But I might ask sceptically in turn if there is a reason to believe that the person who woke up and the person who appears to remember waking up are different persons. This is not a decisive thrust, however. I cannot refute your sceptical doubt.

Good question. We could do with more like this.


It is called continuity. There's a long discussion of this notion in its widest sense in Aristotle's Physics. Although not in relation to memory, it is obviously applicable to that.

It also has a family resemblence to Al-Ghazali's and Hume's notion of impressions not being formally causally connected.

Al-Ghazali's answer was occasionalism: the creation, decreation and re-creation in every moment of time everywhere which for him was mediated by Allah/God.

Although Hume didn't answer his own question, Kant's response was his 'Copernican revolution' where it was the subject's consciousness that tied everything together. I'm not sure if Kant tackled the question of the continuity of consciousness specifically.


You have memories. That's an empirical fact. But what are memories from an epistemological and ontological viewpoint? Memories are stored in between synapses and neurons. They are chemical networks in your brain. They served a purpose in evolution and were favorable genetically. That's why you have memories. Because of natural selection. Did you know that a bacteria has a rudimentary form of memory? Having memory is not sufficient for being a self. There is also no coherent definition of a self within this context either. You are composed of atoms, proteins, chemicals, tissues, organs, and so forth.

Think of it this way...

If you lost your arm, would you still be you?

Your foot?

Your kidney?

A lung?

Your body?

Part of your brain?

You see, there isn't such a thing as an "I" or a "you" — which may be very uncomfortable for you — beyond the fact that you are the unique progeny of your parents. You are a member of the population of homo sapiens on earth but there is no essence that is "you". No perfect form. No idealised notion of a self. Much the same as those who get dementia don't have an idealised form of their identity. You share DNA with all other humans and species but most things you think are constitutive of your identity can be broken down and explained by the laws of nature. Unless you believe you have a soul.

  • 1
    Pardon me but I'm a pedant. It is not known to science how memory is stored, and memory is not an empirical phenomenon. .
    – user20253
    Dec 12, 2017 at 13:30
  • 1
    @PeterJ most neuroscientists cite synaptic plasticity to be responsible for memory formation. If that’s “unempirical” I can’t counter you. See: qbi.uq.edu.au/brain-basics/memory/how-are-memories-formed & forbes.com/sites/quora/2016/02/01/…
    – user28485
    Dec 12, 2017 at 21:58
  • 1
    & ncbi.nlm.nih.gov/pmc/articles/PMC3843897
    – user28485
    Dec 12, 2017 at 22:05
  • I think you'll find that neuroscientists have theories (and hopes and dreams) but none that work. As for empiricism, it is surely obvious that memories are not empirical phenomena. Behaviour that implies memory is empirical but listening to first-person reports is not empiricism and clearly they are not known to us as evidence of our senses. Just as consciousness has no empirical proof nor do memories and for the same reason. Or so it seems to me. .
    – user20253
    Dec 13, 2017 at 13:39

Short answer is you actually don't. In point of fact, there's a better chance statistically of you being a Boltzmann Brain because it would be far simpler for the universe to create your brain in isolation with all its memories than it would be to create a complete universe in which you could come to pass conventionally and collect all those memories directly.

To conduct a thought experiment; imagine it's possible to take the memories in a single mind and transfer them completely to another mind in another body, wiping out the original memories in the process (full transfer of 'consciousness'). What happens when you take the set of memories in a blind person and put them into the mind of someone who can see?

Worse yet, take a healthy person's memory and put them in the mind of a person who's been given a lobotomy?

A part of the consistency of memory is that they are consistent with our own personality, brain chemistry and ability to sense the world around us. That doesn't make it clear that our memories are real, but it does say that if they're manufactured, then someone has gone out of their way to make it seem as real as possible. It would be cases where you can't remember seeing (but now you can) that would be the clear indication that something's wrong along the lines that you mention.

  • 1
    Would it? Occam would disagree I think.
    – CriglCragl
    Apr 28, 2018 at 11:12

"The condition necessary for the act of recollection, is the identity of the being who remembers, with that being whose former states are recalled by memory. To remember experiences of another would be to remember having been somebody else: in other words, to simultaneously affirm and deny one's own identity, a pure and absurd contradiction" (Amédée de Margerie, cited by Michael Maher in "Psychology")

Hey everyone, thank you all for your answers and I'm sorry for not answering directly each and every one of you. I think I may have come across the beggining of an "argument" for the sameness of the subject that remembers some event and the subject that experienced that event.

Let's start with a principle that says that to feel or sense what Jack feels or senses, you have to be Jack. Well, when you remember some event, you remember the sensations felt by the subject of that first person experience. So, you seem to remember being someone else. But I don't really know how to develop the argument from here.

Any thoughts?

  • This might be best presented as a new question. Or added to the original question. Apr 28, 2018 at 13:57
  • Already created a new question ;-) Apr 28, 2018 at 14:43

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .