I realize that the person I am as I type these letters and the person I am at the end of this sentence is slightly different. Change occurs all the time and infact change within my brain is the reason there is a "me" to begin with.

However from there is a continuity, as I started this question and until I'm done typing it out, there has been a continuous "I" and here starts my question: How much change must occur for a certain being to stop existing and the brain developing a completely new person with zero continuity?

Imagine a person who is driving down the road, he gets a text, checks it and consequentially drives right into a semi-trailer. The guy is instantly braindamaged and launched into a coma. His brain is a complete mess and when "he" wakes up 2 months later, he can no longer speak, move his body or think in any shape way or form like he did before. He is drastically changed, but the memories are still intact. So is he the same person as he was on that fateful night? Or did that person genuinely die and then the new reorganized brain gave rise to a completely new person who has false memories?

Or is there no answer to this really? I mean, everytime I go to sleep the continuity is broken, so is there even such a thing as a continuous identity? What about if I smoke some weed and drink myself to the point where I can no longer stand on my legs or speak coherently? Am I still the same in these situations ?

To put it even to a further extreme, say you stumble into a meatcleaver and your entire brain is turned to mush, but then due to a infinitely unlikely occurence every atom that previously made up your brain becomes the atoms that make up a brand new persons brain ( a kid who is just born ), would this be you? I would say "of course not", but then that requires that there is this boundary where given X amount of change it would no longer be me, is there?

  • The interesting part of this question (self-identification) is a cognitive science question. Whether or not it is true depends on how our minds are implemented, and knowing whether or not it is true depends on evidence. That's what CogSci is for. The boring part--can I be wrong about where I intuitively draw the line between calling me "me" and not--is perhaps a philosophy question, but not a very entertaining one.
    – Rex Kerr
    Sep 17, 2012 at 17:46

3 Answers 3


You should try first to define "I", and it's the most difficult job I believe, as a thing cannot see his own boundary.

There is a beautiful example that a person like that of your question gets up from a long coma, he is now conscious but does not remember anything, even his name, he gets embarrassed and the most important thing to him right now is to understand who is he? Or put differently, which "I(dentity)" is his "I(dentity)" and how is he intrinsically distinguished from all the people around. In this symbolic example after a consultation people decide to tie a red ribbon around his neck so that he will be "the one with a red ribbon around his neck"! The person now calms down and relaxes as now he knows himself in a distinguished way. Years passes and hi still lives quite happily. Then a friend of him in a waggishly behavior unbraces the ribbon from around his neck. The person wakes up happily and he finds the ribbon not at its place, gets extremely embarrassed that "Who am I, was all that I think I remember only a dream?".

This was perhaps only a comic example, but actually a rough sketch of the very reality of our common societies. My friends say they know me when they only know me in face, a combination of shape and size and orientation of my eyes, nose, mouth, and etc. but these can change rapidly in an accident while I am still the same "I", only very shocked in a very painful situation. Some say they know me when they only know my name and family name (or student number, or identity number, or also my parent's name, or where I have born, or any other detail of my passport and etc.), these are somewhat a better identification of "I", but yet I am more than only some numbers and names assigned to me, I am something that I can feel it and have an intuitional understanding of it, although intuitional knowledge is not always also accurate! The best way that I know how to understand "I" scientifically is to study it like a black box, I study my behavior against the events of my everyday life. This is called self wisdom, if I am right, in Islam and maybe other religions. People are called to think who they really are, e.g. do they lie when there is a benefit for them to lie? Are they trustworthy in the real life or they just think being trustworthy is good (and without any thinking about their actions know themselves already as trustworthy) and etc.

It is more than obvious to me that each person, if is not studying himself/herself throughly, has a definition of "I" based on how that he/she wants to be, not based on what he/she really is, the ideal personality that all of us make of ourselves in our minds are more or less taken from stories of heroes, but becoming good following the rule "no pain, no gain" is too much superior to only liking (or imagining) to be good.

All this black box studying however is around the black box which may be the very "I" for every person, the individuality of every person, that is called soul or spirit and that's what we cannot understand as long as we remain human (not only alive human), as we remain our "I"s, be it evolved in the course of time or not.


Everything depends on how you define "a person".

If your definition requires continuity of consciousness, and it defines personhood as an all-or-nothing status, then every time a person loses consciousness, when that body's consciousness goes "back online", you would say a new person came into existence.

But that definition doesn't strike me as congruent with a number of important and well-thought-out conceptual structures, such as human neurology/behavioral neuroscience and jurisprudence, as well as just our everyday conception of what we mean by "person" in this regard. So I prefer to see specific personhood as a status that does not depend on continuity of consciousness and with generously blurred boundaries. So, under this definition, no, no new person "arises" as you put it, after and merely due to a period of loss of consciousness.


This is an example of the Ship of Theseus problem. If the ship is replaced one plank at a time, is it the same ship? Check out Ted Sider’s Four dimensionalism for an elegant solution. You may physically change over time, and so the three dimensional “I” can be said to be materially different with respect to time. But if we consider the problem in the context of four dimensions (the fourth dimension being time), we have continuity; three-d slices of us (ie at any point in time) are different, but the four-d whole of us is contiguous.

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