IEET > Rights > Personhood > Minduploading > Vision > Affiliate Scholar > John G. Messerly > CyborgBuddha > Philosophy > Psychology
The Problem of Personal Identity in Two Pages
John G. Messerly   Apr 25, 2015   The Meaning of Life  

The problem – Is a person the kind of thing that can die on earth and be alive somewhere else? To understand this consider a thought experiment. If we make a perfect copy of you—complete with your thoughts and memories—is that copy really you or just a duplicate? (If you think the copy is you, then the waking up in heaven scenario is not problematic; if you think it’s just a copy, then the thing that wakes up in heaven isn’t you.)

Personhood at a moment – What is it to be a person at a particular moment? The bundle theory says you are a body and the mental events in your brain. There is nothing more to you than that. The soul theory says that there is more to you than this, there is a core to you that we might call your soul, ego, or self. So the bundle theory denies what the soul theory affirms—that there is some inner core that is the real you. David Hume, the Buddhists and others denies there is any such core.

Split brains – Modern science accords well with the bundle theory, but not the soul theory. For example, if one severs the brains hemispheres one seems to create different persons. This does not fit well with the idea of a unified soul; but on the bundle theory this is easy to explain—there are just two streams of consciousness. Moreover, if the bundle theory is correct—and science suggests it is—then the prospects of immortality seem bleak.

Personhood over Time – If soul theory were true we could say what personal identity over time means that you have the same soul in the past, present, and future. But on the bundle theory it is hard to see what accounts for personal identity.

Qualitative and Numerical Identity – By identity we might mean identity in the qualitative sense—qualities like patience, humor, honesty, etc.—or we might mean identity in the numerical sense—the same birth date, parents, etc.  So if you meet your old high school friend Jim Smith at a reunion, you might find his qualities have changed. He used to be carefree and now he’s serious. But he is still Jim Smith, the guy you went to high school with who was born in a certain year to Mr. and Mrs. Smith. He is not an imposter.

Now you want to be the same person in the future (or in heaven) that you are now;  you want there to be numerical identity. Otherwise you will no longer exist. But what theory might explain this numerical identity? Here are some theories.

Body Theory – x is the same person as y because they have the same body.

Problems – 1) this rules out post-mortem existence because your body will decay; 2) the prince who changes bodies with the cobbler suggests that identity is not tied up exclusively with bodies; and 3) the story of the “ship of Theseus” parallels the human body story—you do not have the same body that you used to have.

Same Brain Theory – x is the same person as y because they have the same brain.

Problems – One problem with this theory is one can be dead and have an intact brain. This suggests that the brain is not the locale of personal identity. Moreover, the brain’s physical structure changes over time even if the neurons are relatively stable.

Memory Theory– x is the same as y because they possess the same memories. (This explains the prince and cobbler, the prince is still the prince even in the cobbler’s body, and it appears to make post-mortem existence possible.)

Problem – Our memories are limited. So if memories make us who we are—we aren’t much. Furthermore, how can memory theory account for personal identity when being “the same person as” should be transitive across time? But memories aren’t transitive across time in this way. At 60 you may remember your 30 year old self, and at 30 you may remember your 10 year old self, but at 60 it is hard to remember your 10 year old self.

We might revise memory theory to deal with these objections by introducing the “memory-links theory.” In this theory x is y because there is a chain of memories linking a person; persons have identity based on psychological continuity. The problem here is how much psychological continuity there really is.

Moral responsibility – Another reason to accept the memory theory is that it fits well with our idea of moral responsibility. The argument is simple:

  • memories imply responsibility
  • responsibility implies identity
  • thus, memories imply identity

Problems – It seems you could remember a past action and no longer be responsible for it because you have changed. Why should I be responsible at 60 for something my 18 year old self did? So responsibility should depend on a person being the same person qualitatively, not just on being the same numerically.

Is the memory theory trivial? – If our memories are unreliable, then they can’t be the basis for personal identity; but even if our memories are reliable, that doesn’t say much about personal identity. Here’s why. If I say: “I am the same person as I was twenty years ago because I remember being the same person,” then I am just presupposing that I am identical with my past self. But that doesn’t show that I am identical.

Conclusion – Philosophers generally agree that soul theory explains nothing, but that bundle theory and some form of psychological continuity best explain personal identity. In addition, accepting the kernel theory gives us good reasons to be selfish; whereas the bundle theory may lead to more concern for others.

(This entry relies heavily on James and Stuart Rachels’ book: Problems from Philosophy.)

John G. Messerly is an Affiliate Scholar of the IEET. He received his PhD in philosophy from St. Louis University in 1992. His most recent book is The Meaning of Life: Religious, Philosophical, Scientific, and Transhumanist Perspectives. He blogs daily on issues of philosophy, evolution, futurism and the meaning of life at his website:


Is it possible to copy oneself and live in some other realm; the virtual or any another body? Inspiring article. Let’s start with the question of what is the self? The self is the dynamic system consisting of all brain functions along with a complex bio-chemical structures that result in neural activities of the brain, which are wired through the unique synaptic pathways created on the base of one’s experiences that always appear to be unified and projected as one’s consciousness that knows itself through the veil of time. As the rationalists philosophers and I. Kant stated, the unity of all experiences are condicio sine qua non of a self that is active along with the body and its biological structures, habitual aspects relevant to the socio-biological environment, and engages through all social interactions.

I follow daily news on advanced technologies, neuroscience, and I’ve read popular and scholarly books related to neuroscience, transhumanism, cyborgs, the ideas of “upload” and “download” knowledge through the human-computer interface. As to my understanding, with the exponential computing predictions, in the future it will be possible to “upload” the complex brain information of one self into the computer that will need to be built as the blank model of the human brain (Blue Brain Project, IBM). This artificial “self” would not be any longer something existent in time relevant to a human experience, and therefore, would be just a trapped copy of one’s neural information transformed into a machine. Logically, if in the future, will be possible to “upload” one’s complex neural and memory information into the computer, then, likewise, would be possible to download the same from the virtual (computer) into a new living body. Since, the synaptic pathways and information would be transformed into another body, then you might again live as the “self,” but you will be exposed to another “experiential” time and slightly different biology of the body, so the “primer” self would begin changing. The question will be, can the self, maintain under any of “upload” or “download” transfers the integrity and unity of the self through knowing itself?

If the self will be able to know itself (I think, therefore I am and I remember), then you might have a copy of the self, if not, it’s a good thought experiment. 😊 This is the epistemological perspective on this problem that is based on basic of scientific and philosophical knowledge. Though, we should not forget that this question is a key element of Eastern philosophies who relate to the concept of karma, Hindus, Buddhists, Jains, and practices based on yoga and enlightenment.

The concept of karma posits the same question—do we live after death and can our self be transferred into another body? The same question, just the different perspective. For the Eastern traditions, who have embraced the concept of karma, there is always the ultimate bias of every living self, which is the atman—the essence that is not just represented as the unity of the self, but also as the unity that mirrors the the ultimate reality (the underlying information about the universe). The atman is usually translated as the soul that corresponds with the ultimate reality. This soul is capable of changing many bodies, and having many selves, which bias is one. If the body fails due to sickness, accident, then the self preserves traits and key memories, and changes the body, but carries the underlying atman along with the “dead copy of the self.” Information is accumulated, never lost and it is present in the next body, because information based on light of consciousness is never lost. 

So, my question is : If the self relies on the unity of all experiences, does the modern neuroscience or epistemology have any coherent explanations for what is exactly the unity of all experiences and how is attained? If the science doesn’t have any answer on this question, we are far away from any copy job of the self.  The unity of all experiences is not based only on memories, or a memory, but on an active memory that acts as a motivational pulse on the base of synaptic patterns and directs the self from a moment to a moment, or from a “lost times” to the same coherent moment based on that unity, and opens a future discourse for a person, where all of the fruits and ghosts are fallen from the tree of knowledge: free will, longings, love, empathy, desires, right and wrong actions.

The Eastern philosophies at least offer some coherent theory of how is the unity of all experiences is possible, and explains that a part of the self is always “copied” into a new life-form. Unfortunately, the academic philosophy and mainstream science still doesn’t offer even the coherent theory on this question, but still extensively experiments trying to find the way how to “upload” or “download” a memory, knowledge, or even the self through advanced technologies. We might end up with designed copycats, not copies of the selves. 

I think that any serious consideration about personal identity cannot ignore the position called “Open Individualism”, promoted by Daniel Kolak, which is a modern version of monopsychism. This view is underestimated because it seems to be philosophically indefensible, but if you evaluate it with accuracy considering also the conceptual revolutions of Physics in the ‘900, you may see that these difficulties are not so different by the ones that you meet considering all the alternative theories. Me and other people came independently at the same conclusion presented by Kolak, and we founded a group on Facebook.

There are many approaches possible. My current view can be summarized shortly in being eliminativist about the concept of identity, and reductionist about the rules that allow the emergence of the mind. So any given state of mind must be supported by some material brain state, but there’s no “identity of the mind” neither “identity of the brain”. Each stream of consciousness creates its own subjective time, flowing in a common eternalist framework. In this way, there’s no need to assign any absolute identity to anybody or anything in general. The “experience of subjectivity” is like an actor that plays all the characters in a movie.

You may find more information and references in our Facebook group “I Am You: Discussions on Open Individualism” and in my web site at

YOUR COMMENT Login or Register to post a comment.

Next entry: The Vision Thing

Previous entry: Review of EX MACHINA