"Voodoo Doll Louvre" by Jastrow licensed under CC BY 2.5 cropped by Nick Byrd

Personal Identity: Taking Vantage Points More Seriously

(Image credit: “Voodoo Doll Louvre” by Jastrow licensed under CC BY 2.5 cropped by Nick Byrd)


Suppose the following about persons.

    1. Persons have sensory experiences from certain vantage points
    2. Persons’ have psychological states
    3. Sensory experience and psychological states can vary as a function of vantage point

How does this effect personal identity? To put it briefly, it would mean that for one person to be identical with another, then (given Leibniz Law, strictly enforced) the persons would have to be identical according, at least, to the following variables:

    1. Sensory experience and psychological state(s)
    2. Vantage point(s)


Persons as Information Gatherers. The impetus of this view of personhood is the idea that persons are, among other things, information-gathering beings. Consciously or not, they ‘gather’ information—and sometimes the information is stored. Here’s the kicker: gathered information—whether it is being attended to or not, whether presently in the field of consciousness or stored from a past field of consciousness—is a necessary property of personal identity.

Information Varies Depending Upon Vantage Points. From this claim about persons I add another: persons, necessarily, collect information from a single location in time and space—henceforth, this location will be called a spatiotemporal vantage point. Persons cannot collect information from multiple locations in time or in space; they also cannot collect information from ‘outside’ of space or ‘outside’ of time—whatever that would mean.

Having described spatiotemporal vantage points, I add another claim: information gathered from a spatiotemporal vantage point is unique to that point. Thus, information from two non-identical spatiotemporal vantage points is non-identical. When I gather info from spatiotemporal point A and you gather info from non-identical spatiotemporal point B—even if we are gathering info about the same event—our info is not identical.

Camcorder Analog. A useful analog for the idea of personhood hitherto outlined is a digital camcorder. It gathers visual and auditory information and stores is on some sort of memory device. The information that is gathered is unique to the spatiotemporal vantage point from which it was gathered. If two camcorders gathered footage of the same event, but from different times and/or spaces, then the footage would not match — this could easily be verified by watching the footage.


There are a couple benefits to this claim about personal identity:

    1. Avoids location problems. Problems follow is either (i) location is not a property or (ii) location is a property. My commitment to vantage points allows the benefits of a location-like property by smuggling in the concept vantage point (which involves location). Indexing vantage points allows us to pick out one person from another based on something like location, but less problematic than location simpliciter. So two persons are different if they occupy different locations, but one person does not become a new person every time they occupy a new location because their locations share something in common: a chain of connected vantage points. Also, this view makes co-location impossible. If two identical persons occupy the same vantage point, then there is only one person at said location.
    2. It’s intuitive. The main hesitation with many theories of personal identity is that they seem counter-intuitive — sometimes so much that comprehensive revisions to language and social practice would be required were the theory to be true. My commitments concerning personal identity allow persons to be picked out in ways that are not uncommon for philosophers and non-philosophers alike. Think about duplication. My students often tell me that duplication results in two new people because, after all, once the two persons begin living separate lives (and occupying different vantage points), then their identities deviate from one another.

There might also be concerns:

    1. It’s counterintuitive. If I had not chosen to do X (or not had the vantage point Y, or not had the psychology Z), then I would be another person! This means that whenever I actualize one of a few possible options, I shape my person in a sort of irreversible way. This might offend some people’s intuitions. I find it rather palatable. Indeed, I think this dovetails nicely with philosophical and empirical work on character formation, habit, implicit association, etc. But more importantly, a counter-intuitive result is not devastating. My goal is not to satisfy everyone’s intuitions — I’m not sure that’s a realistic goal. Rather, my goal is to make sense of many common judgments and provide explanatory power. This view allows for that.
    2. [Your suggestion here]


If what has been outlined is true of personal identity, then a few implications follow:

  1. Personal duplication is impossible: once two persons—whether the product of duplication or not—are gathering information that is exclusively available from each non-identical spatiotemporal vantage point, then the persons are non-identical. This conclusion relies on Leibniz’s law being enforced such that when person 1 gathers information X and person 2 gathers information Y, the two persons’ non-identical information deems them non-identical. This means that personal duplication thought experiments will have much less to offer the domain of personal identity.
  2. Neither the somatic or the psychological view of personal identity are independently sufficient. Brains (or psyche’s) cannot sufficiently account for identity since the brain relies on the body to gather information and the content of gathered information is a direct consequence of the spatiotemporal location of the body that gathered it. So, both the body (its ‘stuff’ and its spatiotemporal location) and the brain (or the psychological content) are necessary elements of personal identity. In this way a person is, among other things, both a physical thing at which one can point—”That guy over there!”—as well as an informational thing that can be ‘picked out’—”The guy with ‘such-and-such’ mental content who occupied such-and-such vantage points.”
  3. Neither internalism nor externalism about personal identity are right. If both internal states and environmental features like sensory input and vantage point are part of personal identity, then personal identity is not entirely an internal or entirely an external phenomena. It is both. This strikes me as a happy conclusion since many debates strictly internalist and strictly externalist views seem to be distinguishable with counterexamples. So, it seems that a principled middle view is probably best. The present views allows one to hold a principled middle view.

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Nick Byrd

Nick is a cognitive scientist studying reasoning, wellbeing, and willpower. When he is not teaching, in the lab, writing, exercising, or relaxing, he is blogging at www.byrdnick.com/blog

24 thoughts on “Personal Identity: Taking Vantage Points More Seriously”

    1. This is a good question. I think it is entirely possible that zygotes are persons. According to my commitments, the trouble will be showing whether or not it has a psychology. What do you think?

    2. Janice: if a zygote is a person, then so is a bumblebee or an ant. These are at least as likely to have a psychology as a zygote.

  1. I am not of the opinion that zygotes could be persons. And I do not think they have rights to a woman’s body.

    1. I see. Well, if a good reason could be given for why a zygote does not have a psychology, then I suppose I would be on your side, as it were. Thanks for sharing!

      1. I think it’s safe to say that “having a psychology” necessarily involves representations of inner states. A single cell doesn’t contain such structures. It has inner states, but no “self monitoring unit”.

        The same applies to “sensory intake” and “volition”, these require representations of outer and future states.

        1. While I remain agnostic about one might mean by representations, I am inclined to accept your claim that single cell organisms do not have what it takes to have a “psychology.” The tough bit about that claim, though is one of vagueness.

          At some point, formerly single cell organisms could have enough cells to support representations of inner states. This means that there could be some magic formula of the amount/composition/etc of neurons required for a psychology. Take for example a simple organism that will inevitably have a psychology (e.g. human fetus), then should it count as a person before it has a psychology or only after it has developed a psychology? If the latter, then we will have a really hard time determining when it becomes a person. Also, the latter entails that persons can pop into existence in the form of complex organism. That last claim could offend our intuitions.

          So if you are right, and I am inclined to think that you are, then personhood quickly gets complicated.

          1. Well, a zygote doesn’t “inevitably” become a person. 50% are aborted spontaneously (source: http://www.nlm.nih.gov/medlineplus/ency/article/001488.htm). The other 50% develop into one or more persons (twins, triplets, …). A theory of personal identity that regards zygotes as persons runs into unsolvable problems: If twins once were one person, what has become of that person? If not, can a single cell be two persons?
            So yes, I think it’s complicated :-).

          2. The spontaneous abortion is less of a problem than the twin scenario. I should not have used ‘inevitable.’ I meant to refer to Don Marquis’s concept of a being “with a future like ours” (PDF here, pg 6). If the conditions are right, then a zygote will become at least one being with a future like ours.

            I admit, however, that I had completely overlooked the twin (or triplets, etc.) possibility. That definitely pushes me toward ruling out the possibility of a zygote being a person. Still, it is logically possible (and consistent with my commitments) that a zygote could undergo personal fission when it becomes multiple organisms. Via my commitment about vantage points, all resulting persons would be unique, which seems fine. My hold up is this: the idea of personal fission seems thoroughly strange.

            Thank you for brining up these important points Raphael! I owe you one.

          3. I just found this paper (Stier and Schoene-Siefert, 2012) on the problem you revealed. It deals with the argument that embryos should be treated as persons in virtue of their potential to be persons. It outlines a couple renditions of this potentiality argument and exposes a few of the problems with it. It is concise and well put.

          4. Isn’t it the case that the structure of a cell is a representation? Not of inner states, but a physical and highly organised representation that is reflective of the conditions of its environment. If it were not an accurate and informed representation of the conditions of its environment, it would fail to survive.
            Similarly, the personal identity of a human requires conceptual representation.
            Perhaps there are different types or classes of representation that build or emerge from one another…

          5. I am unsure about two of the claims you are asking about.

            1. “The structure of a cell is a representation.”
            A representation held by itself? It seems that this might be an empirical claim that could only be validated by adopting a behaviorist conception of the cell. We would have to ask questions like, “Does the cell behave as if it is a representation of itself?” Perhaps I am just unimaginative, but this seems like a strange question to be asking about a cell.

            2. “Cells would only survive is they had an accurate and informed representation of the conditions of its environment.”
            This seems like a very strong claim. It seems that it’s logical conclusion is to attribute something like representational consciousness to any living thing. I am rather hesitant to embrace such a view until the claim itself is supported by evidence. Also, it seems like it is possible for a cell to not represent itself and to survive (since, I presume, most biologists do not presume the cell to have representations of itself).

            Perhaps I have misinterpreted you though. Feel free to say more if I have done your comment injustice.

          6. I was excited to read your comment, “It seems that it’s logical conclusion is to attribute something like representational consciousness to any living thing.”, but I would hesitate to jump the gun by pinning on the label “consciousness” just yet…

            I did not mean a representation “of itself”… and I am not sure what you mean by a representation “by itself” – Rather, I meant it more broadly; that a cell is an ‘informed representational construct of its environment’ – its structural form ultimately being a successful culmination of environmental interactions.
            Consequently, I would then want to ask what different types of representational construct there could be; where the accuracy of a construct’s representation determines its stability and longevity; and its construct, whilst being physical, need not necessarily be material.

            After establishing the different types or classes of representational constructs, it then remains to determine why they evolve, what are their unique characteristics and how one type leads to the emergence of another.

          7. I see. So there is no commitment to consciousness here.

            Still, I am unsure how to interpret ‘informed represented construct of its environment’ in a way that does not attribute knowledge to the cell. And if we attribute to cells knowledge of their environment, then I wonder would what motivates us to do this. For example, is it that the cell responds to environmental stimuli so successfully (and that it therefore survives remarkably)? If so, then we might attribute a representational capacity to all sorts of things(!)—but perhaps this is what you have in mind.

            As you can tell, I am having trouble conceiving of the ‘representation’ you have introduced. My persistent confusion could very well be the result of my not being familiar with your work and its ilk, so I apologize. Alas, I am having trouble overcoming a sort of intuition-level objection to the idea that cells are (a-consciously) ‘informed’ of their environment via ‘representational construct.’

            An alternative example might help me understand you better. Imagine a robot that can navigate tricky terrain. It responds to uneven grades, environmental disturbances (e.g., wind, things moving in it’s environment), etc. This behavior is simply a result of its hardware and software cooperating well. Would you say this robot is capable of the same ‘informed representational construct of its environment’ as a cell?

          8. You say, “I am unsure how to interpret ‘informed represented construct of its environment’ in a way that does not attribute knowledge to the cell.” I am delighted to hear you come up with this query. Most people think of knowledge, as being related to the reasoned or informed decision making that comes about from brain activity – i.e Knowledge is at the root of the decisions that determine only animal or perhaps only ‘human’ behaviour. And I understand your intuitive “objections to the idea that cells are (a-consciously) ‘informed’ of their environment via ‘representational construct.’”

            But consider the following:
            The complex nature of creating sugars from light, water, and carbon dioxide indicate that the evolved biochemical physiologies of plant cells exhibit the ‘knowledge’ that enables photosynthesis to take place. It is by virtue of the complex structures and behaviours themselves, that organic structures demonstrate that they possess a certain knowledge regarding their environment.

            Thus we might look at the evolution of information constructs; as the evolution of different levels of sophistication of ‘knowledge’ about the environment – if we broaden our interpretation of what ‘types’ of knowledge there might be…
            Alternatively, information about the environment is ‘encoded’ in different ways by different construct forms; where information is any physical state that demonstrates its competence by mitigating the destructive capability of the environment.

            Consequently, you are correct in saying that “we might attribute a representational capacity to all sorts of things”. What sorts of things?

            By considering, ‘what sorts of things?’, you ask of a robot – Is a robot “capable of the same ‘informed representational construct of its environment’ as a cell?” This is a critical question, one that ultimately determines the requirements of artificial consciousness applications, but at this point, over complicates the task at hand. Alternatively, consider only natural phenomena; specifically regarding the evolution and spontaneous emergence of different classes of representation:

            What types of representation are there?… Include considerations regarding the nature of phenomenal experience and of conceptual thought.
            Can the different types of information/ knowledge types be classified? And how and why does one class, emerge from the other? Do they determine distinctive and unique behavioural consequences and characteristics?

          9. I still find myself uneasy about saying that things like cells have knowledge. Perhaps their ability to “mitigate the destructive capability of the environment” can be explained by a passive, non-intelligent phenomena like evolution. In this case, the cell is successful not because it has knowledge of its environment, but because it is the only biological structure that can be successful at survival/reproduction (given the law-like features of the world).

            I have the feeling that I have ventured well outside my comfortable realm of naturalist philosophy in all of this. I can barely tell if what we are talking about is sensible. I do not mean this as an insult. I mean it only as a confession.

            Perhaps our conversation will seem more sensible once I take a look at your book project—that is, if I ever get a chance to do that.

          10. You are absolutely correct in saying, “Perhaps their ability to “mitigate the destructive capability of the environment” can be explained by a passive, non-intelligent phenomena like evolution.” I like “the passive, non-intelligent phenomena” idea.

            I am in agreement that:

            i) Evolution is the vehicle – by merely replicating, a systems construct (i.e. an organism) has no control over its acquisition of knowledge but instead relies on evolution.

            ii) The organism is not in control – the process of knowledge acquisition is passive.

            iii) There is no intelligence – by which one might mean; that there is no evaluative mechanism for the acquisition and implementation of the knowledge – it is environmentally reactive i.e. there is no ‘active’ involvement

            Some animals possess only innate predetermine behavioural responses. With these innate responses they might sense their environment and move about it through some predetermined response. I would argue that their neural structure ‘knows’, for good reason, how it must respond for optimal survival. Similarly, a plant will turn to follow the sun. It ‘knows’ where the sun is – admittedly not because of any neural process, but like innate animal behaviours, the process is chemico-physical.

            Innate behaviours are passively acquired by their respective organism, because of evolution… there is no active intelligence or active evaluative mechanism in either the acquisition or display of this knowledge.
            Of plant cells then, we have an uncontrolled, non-intelligent, passive knowledge complex.

            Nick… you are on the money thus far. So… what of ‘active knowledge’?
            How does it emerge from passive knowledge; what is the vehicle and the mechanism; how is active knowledge acquired; what are its distinctive unique behavioural characteristics?

          11. That seems to be an empirical question, but as far as I know it is unanswered. My knee-jerk answer is that it has to do with conscious awareness. “Active knowledge” would be the same as the “passive, non-intelligent” knowledge, except that an organism is aware of it (but that is not to say that the organism is commander or author of it).

          12. “Conscious awareness” is jumping the gun a bit.
            What physiological mechanism enables the active acquisition of knowledge about the environment?
            What is it about this kind of actively acquired knowledge that differs to the evolved non-intelligent physiological knowledge of organisms like plants?

  2. As a general point… I think you need to clarify what you mean in your use of the term ‘psychology’. “Persons have psychology” is too broad or vague to mean very much. What is the psychology that they have?

    1. Mark: I agree. A couple things.

      1. This post was from a year or two ago, so I am not sure I would use ‘psychology’ again if I had to rewrite this today.

      2. At the same time, I am talking about personhood here, and not consciousness or something else that entails an empirical claim. So, I am hesitant to make claims that are so specific as to be an empirical claim.

      All in all, your point is a good one. I wish I had more to say about what I mean by ‘psychology,’ but I have not revisited this topic much in the last few years. Perhaps I will sometime soon and I will carve out something more precise.

    2. Mark: per your point, I have dropped the term “psychology” in favor of a more specific phrase “folk psychological states” (point number 2 in the beginning). While this is more specific, I am disappointed that this is the best replacement I have thought up so far. After all, folk psychology is just that: folk psychology. Then again, persons are things that are picked out by the folk, not by sophisticated scientific tools for measurement and detection.

      Thanks again for your persistent feedback!

  3. Point 1 – “Folk psychology” definitely helps me get a better idea of where you are coming from.

    Point 2 about personal identity – To identify a triangle we might say that it has 3 sides:

    ex1. Consequently, two triangles might be identified as triangles by observing that they have 3 sides. But we can only say of the two triangles, that they are similar. i.e. they are not identical.

    ex2. Two triangles that occupy the same spatio-temporal place, can be said to be identical. They have 3 sides; and those 3 sides are of the same length; and those lengths occupy the same location in time and space.

    In ex1 we have two triangles with the same identities but with dissimilarities.
    In ex2 we have two triangles with the same identities but with no dissimilarities.

    However, what we cannot say of the two triangles in example 2 is that they have the same personal identity.

    Similarly, to talk of people occupying the same spatio-temporal location is only to say that they are identical and is not definitively to say that they have the same personal identity.

    To state otherwise, is to fudge the question of personal identity – The distinction between ‘identical’ and ‘same personal identity’ requires a definitive understanding of “person”, in the same way and with the same confidence that we compare and distinguish a triangle from another by virtue of certain geometric measurements.

    Thus, and importantly, we cannot assumethat the distinction of personal identity is spatio-temporal, nor can we feel satisfied with a description that is spatio-termporal unless the complex geometrics (or whatever) of “person” are defined with a complete description.

    This is the essence of the problem of personal identity as I see it.

    Please feel free to comment on my two essays on personal identity at these addresses:

    1. Mark: I am confident that everything I have said so far is in agreement with your analysis, including the triangle analogy. I mention spatiotemporal location only to claim that it is—among other things—required for two persons to be considered identical. And since two persons, as far as we know, cannot occupy the same spatiotemporal location, I then claim that personal duplication (i.e., making two personally identical persons) is impossible. I would also be comfortable saying that no two persons are identical—again, assuming that no two persons can occupy the same spatiotemporal vantage point.

      I will try to read those essays ASAP. Thanks for your comments!

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