Identity, a neurobiological perspective

320x240by William Skaggs

The philosophical problem of identity is epitomized by the paradox known as the “Ship of Theseus.” Suppose a ship is rebuilt by removing one plank at a time, and replacing it with a new plank of the same shape and material. Is it still the same ship? Most people would say so. But suppose all the planks that were removed are brought together and used to construct a new ship of identical form. Wouldn’t it be more appropriate to say that is the same ship as the original, and the one with new planks is a duplicate? There is no easy answer. Every possible reply seems to lead into a morass.

The Ship of Theseus and several related paradoxes have been tangling philosophers in knots for thousands of years, dating back to the ancient Greeks and continuing with Locke, Hume, Kant, etc. It is easy to get a sense that no real progress has been made: after all the modern philosophers have spoken, the paradoxes seem just as paradoxical as they did to the ancient Greeks. It seems to me, though, that there is a route to a clearer understanding, by looking at identity in a different way: from a cognitive neuroscience rather than philosophical perspective. I propose to examine identity as a mechanism that the brain uses to organize the world of perception.

The basic premise is that at a cognitive level, an identity is a label attached by the mind or brain to a portion of the world, usually one that is continuous in space, time, and form. To motivate that premise, it will be useful to briefly examine the way that identity comes into play in modern physics and in computer science.

Identity in physics

The concept of identity is so deeply built into our thought processes that it is hard to examine. Cognitively we live in a world of things, each of which is a distinct individual object and remains the same over time, as long as it continues to exist. It seems impossible to imagine a world that is not divided into things. However, the world of modern physics is just such a world. In modern physics, objects are merely clusters of matter and energy that cohere for some period of time — they have no deeper reality. In modern physics, even subatomic particles do not have individual identities.

It might help to understand this point to consider a hurricane. We think of a hurricane as a distinct entity, but really it is just a temporary arrangement of air and wind. The air that makes up a hurricane on one day has nothing in common with the air that makes it up on the following day. Its edges are indefinite in space, and its birth and death are indefinite in time. As an entity, it is purely dynamic. It shows rough continuity in space, time, and form, but no continuity in substance.

In modern physics, there is no level of identity higher than a hurricane. Some arrangements of matter may last much longer, and have borders that seem less arbitrary, but these are really just matters of degree. For a hurricane, it is reasonably easy to see that its identification as a distinct entity is a process performed by our brains. It is not quite so easy to see that the same fact applies to objects such as rocks and bodies, but it is just as true.

Once it is accepted that identity is a structure our brains impose upon the world, two basic questions follow immediately. (1) Why do our brains organize the world as an array of individual things? (2) How do our brains do this? That is, what is the neural mechanism for assigning unique identities to parts of the world and tracking them over time?

Identity in computer science

The value of identity might seem intuitively obvious, but it is useful nevertheless to see how it comes into play in computer science, specifically in database programming.

A database, to a programmer, is a collection of data organized into “records” and “fields.” A “record” represents the data that comes from one individual entity — perhaps a person, place, website, purchase, data point in a scientific experiment — really any sort of thing. A “field” represents some property of that entity. For example in a database used to hold a record of transactions for a corporation that sells things on the web, each record might represent one specific transaction, and might have fields for the customer name, address, credit card number, item purchased, price paid, date and time of purchase, delivery tracking number, etc.

In most databases there is some field that serves as a “unique identifier” — in other words, a field that serves to pinpoint each specific record and distinguish it from all other records. Sometimes unique identifiers are taken from pre-existing information. For example, in a database whose records represent people, it is common to use the social security number as a unique identifier. Everybody (within certain populations) has one, and no two people share the same one. Another frequently used unique identifier is a credit card number: no two people should ever have the same one. In many cases, though, unique identifiers are generated essentially at random. For example in a database of transactions, there might be a field for the “transaction number,” which is obtained by adding 1 to the transaction number for the previous record.

The function of unique identifiers is to avoid confusion. If the database is searched using other fields, such as name or date and time of purchase, it is hard to guarantee that the wrong record won’t be retrieved. But any record that has the correct value for the unique identifier is sure to be the correct record. Thus unique identifiers work to keep information in records that are similar in some way from getting mixed up with each other.

The only really essential property of a unique identifier is uniqueness. There must never be two records that have the same identifier value. This property is so useful that it justifies using database space to store fields that have no other meaning.

A consequence of uniqueness is that identifiers are usually arbitrary and are typically generated by some central authority. If identifiers have information coded into them, or if they can be generated by multiple agents, it is hard — not impossible, but hard — to avoid the possibility of two records ending up with the same identifier. Think about social security numbers: they don’t carry any information about a person (actually they do carry a little bit, but by accident), and don’t serve any purpose except to distinguish a person from everybody else in databases.

Identity in the brain

My premise is that the human brain contains a database consisting of memory-records of clusters of matter (“things”) that are continuous in time, space, and form, and labels these memory records with unique identifiers that we call “identities.” Often we refer to identified entities using names or certain types of descriptions — “John Q. Jones,” “the planet Jupiter,” “my car,” “this house” — but those are not unique identifiers. The unique identifiers are cognitively opaque.

Why does the brain do this? Because individual things — continuous clusters of matter — often have properties that remain valid over time, but are not easily discerned. Individual people, for example, have personality features that remain generally valid, but can only be recognized on certain occasions. Labeling things with identities allows their covert features to be tracked across time.

Identification — the term I will use for this process — is so deeply built into our cognition that it is hard to think about it clearly. It is hard to think about the world at all without thinking about it as a world of things that remain the same over time.

The process of identification obeys two basic rules. The first is continuity. In order to be identified as the same thing, a cluster of matter must change location continuously and change form continuously, without any time gaps. Thus if I make a fist, it remains the same fist as long as I keep my hand clenched, but if I open my hand and then clench it again, it becomes a different fist. This is however a soft rule, and we are open to the possibility of it being violated to some degree, as in the Star Trek Transporter and the Ship of Theseus.

The second rule is uniqueness, and this one is inviolable. The rule that an identity can only have one exemplar is so deeply built into our thinking that violations seem almost like logical contradictions. But it is really no more contradictory for two bodies to be the same person — to have the same identity — than it would be for two people to have the same social security number.

Why is the uniqueness rule inviolable? Because the way our minds work depends on it. We remember information about things by linking that information to their identities. If two clusters of matter are labeled with the same identity, then it is impossible to keep any distinct properties they might have from becoming confused in our minds.

Solving the paradoxes

If these premises are accepted, then the explanation of paradoxes such as the Star Trek Transporter and Ship of Theseus is straightforward. They work by setting up scenarios that force us to violate the rule that an identity can only have one exemplar, and we simply can’t do that.

Consider the Star Trek Transporter: the scenario is that the Transporter fails to work properly and leaves an exemplar of Kirk on both ends. Which one is the real Kirk? The obvious answer is that they are both the real Kirk, but our minds can’t process that. We can’t think about the two exemplars distinctly unless we assign distinct identities to them. But there is no way to do so without making a decision that seems arbitrary — hence the paradox.

Neuroscience questions

If we accept that an identity is a label attached by the brain to a cluster of matter, then we immediately get several questions about brain mechanisms. How are identities generated and stored by the brain? The answer is unclear, perhaps largely because nobody has been thinking in these terms, but surely must involve the inferior temporal lobe (the terminus of the so-called “what” stream).

And if Identification is a brain process, which animals other than humans have it? The answer is not clear at all. It seems possible to get highly sophisticated behavior without Identification — by responding only to the directly perceptible features of the environment. It does not seem likely that Identification is ubiquitous throughout the animal kingdom. However, it seems likely that Identification is a necessary precursor for the processes known by the term “Theory of Mind.” It’s hard to see how knowledge and beliefs can be attributed to another animal without first representing that animal as a uniquely identifiable individual.
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William Skaggs is a neuroscientist and science writer. His specialty is learning and memory, and he has a longstanding interest in the scientific study of consciousness. His twitter handle is @weskaggs, and he maintains a personal web site for his writings.

124 thoughts on “Identity, a neurobiological perspective

  1. BMM, this is a warning about language, your post barely made it through my filter. Try to make your points more constructively and especially less arrogantly. Thanks.

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  2. Aravis,
    how the brains creates a good working model of external reality — is certainly interesting, but it isn’t a solution to any philosophical problem.

    BMM,
    Let’s have some peer-reviewed science cited shall we

    Let’s lighten up a bit, shall we?
    This is not a formal meeting of the Soviet Academy of Sciences, this is a salon. The host invites someone to make an interesting, stimulating or provocative presentation and a conversation ensues. The conversation is the whole point of a salon, its heart and soul. So let’s get into the spirit of it and converse. Let ideas flow without the threat of the dull deadening discouragement of orthodoxy. Let us explore, let us add new ideas to the conversation, be they insightful, contrarian, whimsical, unorthodox or just plain fantastical. Among them we may even discover discover nuggets of pure gold.

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  3. Aravis, as much as I value your commentary on SciSal, I’ll stick to my comment/question and don’t see your having special insight into what motivated the author or whether it meets your personal expectations of what he may or may not have accomplished in writing the article.

    This is a short piece regarding a topic of general interest posted on a blog that professes to reach a general audience, not simply those with philosophic interests. Your apparent insistence on demarcating the topic as a “uniquely” philosophic problem, given the venue, seems largely self-serving.

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  4. @Bill Skaggs,

    Lots to think about.

    Definitely not my field but considering what I know about the brain I don’t see how it could be using cognitively opaque unique identifiers or how they could be implemented. As others mentioned I think what is usually meant by identity is context dependent and relatively fluid, and to carry out the task of tracking identity, which obviously the brain can do, I think the process needs to start ‘below’ the cognitively opaque level you refer to.

    I think identification is not limited to humans or ‘higher cognition’ and the process of enti-fication and identi-fication started at least as soon as organisms had what we call “not much more the rudimentary beginnings of a brain”. There is a range of complexity that can be looked at in ‘lower’ organisms, and I feel it’s possible to keep a relevant and coherent thread on identity (more complex as more complex organism are considered) no matter the ‘level’ of the organism, including through infant development on into human adulthood.

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  5. Thomas, well, though Aravis’ turf defense may be a bit too strict, he does have a point. The very beginning of the essay makes it abundantly clear that this is another example of science coming to the rescue of poor philosophy, while the rest of it – while interesting and thought provoking – simply doesn’t deliver in that respect.

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  6. Thomas Jones wrote:

    Your apparent insistence on demarcating the topic as a “uniquely” philosophic problem, given the venue, seems largely self-serving.

    ====================

    Whatever. I quoted to you directly from the article itself. *I* didn’t claim the be solving a “philosophical problem” by way of the neurophysiological account, the author did.

    It would be better to answer the substance of the question than to talk about who is being “self-serving.” Tell me one philosophical problem that is solved by knowing all there is to know about a person’s brain states, when he/she is conceiving of something as having remained the same over time.

    The issue, really, is that the article sets out to do something, but then switches gears and does something else. I do believe, however, that the author *thinks* the brain science helps us with the philosophical question, and that is the reason why I challenged him.

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  7. One reason to keep in mind that identity is a philosophical problem is that to think it isn’t probably means a mistake in understanding it. I would guess that in in computer science it’s important to distinguish between math problems and physics problems, though I would hope mathematicians would not be so self-serving as to insist that math problems are “mathematical.” The mathematician should be generous enough to see the math problem as a physics problem, if that is the consensus, and not foist his “field” on the issue ; )

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  8. A number of commenter have said that the post is about philosophy, with neuroscience as window dressing; I view the exact opposite. Bill is asking how the brain does identity. Philosophy helps pose the question, but only empirical work can give an answer. Perhaps Bill should have cited the beginnings of neuroscientific and psychological data to support the quest. Here are some avenues: the existence of “face cells” and a face-detecting region in cerebral cortex, coupled with the phenomenon of prospagnosia (or capgras delusion, as Bill suggests). Place cells in the hippocampus as a route to understanding the singularity of perception (and how attractor dynamics in neural networks might contribute). Mechanisms of individual recognition in a wide assortment of species and studies of how individual recognition contributes to group dynamics and species survival. Bill has used science fiction, philosophy and computer science to help pose the question, but the question is ultimately empirical, with science to (hopefully) provide answers.

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  9. I am with jqubie on this.
    The article discusses two aspects of identity, that of the participant and that of the observer. These are two very different things. The one is experiential and the other is representational. The representational part of identity is a problem of definition and of categories. We see this as external because we mostly have a shared agreement about it.

    The experiential aspect of identity is more complex and by contrast it is internal. My unique identity is the sum of my historical trajectory, consisting of my episodic memories, my personal narrative, my present experience and my view of the future. This makes me unique and indeed I feel unique as no one has ever been known to share the same narrative trajectory.

    Both experiential and representational forms of identity have continuous threads through time. The experiential thread is one of memory and the representational thread is a physical trajectory through time.

    Where Kirk and the malfunctioning Transporter is concerned, the new, remote self, at that instant acquires an experience and memory that the original Kirk does not have. This gives him a unique identity distinct from that of the original kirk, because he has a new branching timeline. If the Transporter does not malfunction, the remote Kirk is still the same Kirk because there is only one, continuous narrative, despite the physical translation.

    This raises interesting problems for Buddhism and reincarnation. If the reincarnated self has no memories of the past selves, then by this definition, they cannot be the same. The only way they can be the same is if there is some other form of continuity. But what could be the form of that continuity? It must be something outside of what is known today.

    Catholicism solves that problem by claiming that the record of the continuous thread of narrative memories(that make up the self) is preserved in the mind of God but Buddhism has no recourse to this solution because it claims there is no God.

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  10. With due respect SciSal and Aravis, methinks y’all protest too much. My reading of the start of the essay–perhaps since I have no particularly sensitivity regarding whether one reads the introduction as simply an attention grabber or “another example of science coming to the rescue of poor philosophy”–is simply an attempt to introduce the subject of “identity” by way of two fairly well-known thought experiments.

    While it’s plain the author proposes a “solution” on the basis of his premise, many comments, including my initial comment, raise good questions. This is simply conjecture on his part in a short article. There is no particular scientific evidence to support it; nor does he suggest or pretend a strict scientific or philosophic basis for his premise. If anyone suffers from “turf toe,” it’s not the author.

    The last paragraph clearly and transparently suggests the tentative nature of his conclusion. (Lots of conditional statements in the article.) As labnut has already indicated, it is apparent that the author hopes to stimulate discussion in an attempt to draw out objections to his premise. (Successfully, I might add.)

    Aravis: “Tell me one philosophical problem that is solved by knowing all there is to know about a person’s brain states . . . .” Well, that’s a loaded statement, Aravis. What I do think is that “philosophers” are not likely to reach conclusive solutions regarding a theory of mind without scientific findings that create additional conceptual space. Better yet, tell me why theory of mind is a distinctly philosophic rather than a scientific problem. Odds are, you’ll say that both can contribute to this area of inquiry. But, to quote you, “whatever.”

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  11. At this point, then, the chief matter of philosophical interest is in identifying and cataloging the numerous ways in which we use these terms and the logic of those different uses and the ends towards which those uses are put.

    The way we use language is directly related to the way our concepts of things are structured, which is in turn directly related to the way brains process stuff. Relating brain processing to the problem is essentially the same thing as relating linguistics to the problem.

    But we learn different things from that sort of activity than sometimes we are interested in. To make the “the brain works like this” move often simply means that one is changing the question while arguing to have it solved.

    The thing about difficult philosophical problems is that the difficulty often lies in finding a way to conceptualize the problem that allows it to be solved. And very often our philosophical questions tacitly import concepts that we’re not aware of, and which invisibly trip us up. So in some cases, yeah, we do need to reframe or re-conceptualize the question in order to find a satisfying solution.

    Whether the author answered any philosophical questions is for the reader to decide. But It’s not irrelevant to think about the problem with respect to how the brain works, or at what level assemblages of matter become non-fungible, or anything else related to identity that could be considered “sciencey”.

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  12. Brief first comment here. I agree with Aravis and Massimo. In fact, I’m surprised that Massimo didn’t mention something like “embodied cognition,” in fact. Our sense of identity is certainly, per this, in part socially grounded.

    In turn, I tie that back to my previous essay, which, though mainly about issues of volition, also touched on issues of selfhood briefly. “Subselves” don’t just exist in Dennett’s sense of semi-conscious bits conducting an evolutionary battle to rise to full consciousness. We also, with some degree of consciousness, present a “work self,” a “spouse self” if we’re partnered, etc. And, if it’s a large company, with a lot of office politics, etc., there are subselves within that work self.

    And, per Aravis, we make decisions how to organize the presentation of those “subselves,” or parts of self, or “personae,” to use the good old Latin.

    Identity in these senses … well, it has nothing to do with either the Ship of Theseus OR the Star Trek Transporter. And, those themselves have nothing to do with each other, differing, of course, on whether consciousness is involved, or not.

    So, even more than Aravis, I say that we have two different main ideas, and two different essays here. Or, rather, three, really, or at least 2.5.

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  13. brandholm, yes, I’m aware of the “change happens slowly anyway” objection. I think it, as usual, confuses the logical point with the bio-logical one. Indeed, logically speaking it makes no difference whether Kirk’s cells get replaced all at once or gradually. Biologically, however, that’s the difference btw life and death, which I would think ought to count in discussions of identity. That, of course, is part of my recurrent criticism of computationalism: it ignores biology. As a biologist, I don’t like that.

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  14. @Aravis Tarkheena: I’m not sure that anything in philosophy ever really gets settled. If I gave the impression that I thought I had settled anything, let me hastily disavow it. The point I was trying to make is that “identification” plays a central role in human (and probably animal) cognition, and a better understanding of that role can hardly help but inform the philosophical discussion. Even a primitive understanding, I argue, suggests solutions to some philosophical puzzles that are hard to resolve in purely abstract terms.

    This is perhaps analogous to the situation in epistomology. An understanding of how brains acquire knowledge isn’t going to directly solve any philosophical puzzle, but it imposes constraints on possible solutions and therefore can’t help but inform the discussion. There was a time when that claim was controversial, but my impression is that nowadays it is the majority view.

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  15. I’m afraid I’ve lost my ability to keep track of everything that is going on here; from this point all I can do is respond in a hit-and-miss way. I do though want to briefly adress Massimo’s “science coming to the rescue of poor philosophy” comment. There are certainly cases where philosophy gets boggled up and science can help. But it’s a two-way street. There are also plenty of cases where philosophy is necessary to guide scientists to the questions that are important and valid ways of approaching them. Particularly regarding identity, but also regarding many aspects of consciousness, it seems clear to me that the interaction needs to go in both directions.

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  16. jkubie wrote: “Bill is asking how the brain does identity. Philosophy helps pose the question, but only empirical work can give an answer.

    ————–

    Really? Suppose I steal your car tomorrow. You have me arrested for theft. In court, I plead not guilty on the grounds that the car is not yours, since it’s not the same car that you bought back in 2003. You trot out a Lockean account of identity, according to which the car *is* the same car. I, in turn, argue that this notion of identity is really nothing more than similarity, and following Hume (in his skeptical vein), I argue that there is only one true concept of identity, i.e. the mathematical one.

    As silly as the example is, these are precisely the sorts of scenarios in which our conceptions of identity typically get a workout.

    Please tell me how “empirical work” is going to give an answer or even help us at all in finding one.

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  17. To Socratic Gadfly,

    “So, even more than Aravis, I say that we have two different main ideas, and two different essays here.”

    I assumed the essay was starting with a broad view of identity (so mentioning variations), to end with the suggestion how brains actually process identity could potentially act as a “red thread” running through them all. That to me is a single issue and single essay, though it can then be approached&diced as per interest.

    To Everyone,
    Given the image of Kirk and the internal Star Trek reference I assumed discussing personal identity (tied to consciousness) was open for greater exploration… especially as I am interested in how the physical brain creates and maintains an identity of the self. It seems this was a distraction for many here so I apologize to all for that.

    In the broader picture I also support the sentiment that scientific research and philosophy can assist each other, including the issue of identity.

    To Massimo,
    As a biologist myself, I share the same view (or instinct?) that you do. Kirk’s body is definitely wiped out, and so all those cells making up the body were killed. There was a biological death. While starting with the “slow replacement” problem, I was trying to move to a more subtle (and disturbing) question which emerges from things I deal with as a neuro-biologist. Is the self actually continuous in the way we think/perceive? This seems really dependent on organization at the cell and molecular level which is not necessarily continuous though it may seem that way. But I will set this discussion aside, since it appears to be a side issue for the essay, and would require more than 500 words to fully develop.

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  18. Hi Massimo,

    Indeed, logically speaking it makes no difference whether Kirk’s cells get replaced all at once or gradually. Biologically, however, that’s the difference btw life and death, which I would think ought to count in discussions of identity.

    How about if we program the transporter to instantaneously replace all of Kirk’s atoms with a different set of atoms, yet leave him in the same place? Is Kirk then dead and do we then have only a copy of Kirk?

    This scenario is simply the transporter scenario operating over a zero distance, so if you answered that Kirk was still alive, what distance of translation would be required to make it a copy and not the real Kirk?

    If, on the other hand, you answered “dead” what timescale of atom replacement is acceptable for him to still be alive?

    Suppose, in another scenario, the transporter kept the original set of atoms in a heap; then, once Kirk had finished galavanting around some planet and had beamed back, it used that original set of atoms to reconstruct him. Is that then the original Kirk or a copy? Would it change your answer if the time between transporting and re-transporting were reduced, and perhaps reduced all the way down to a nanosecond?

    Hi Aravis,

    Suppose I steal your car tomorrow. […] Please tell me how “empirical work” is going to give an answer or even help us at all in finding one.

    In such scenarios the court would turn to the “man on the Clapham omnibus” understanding of the issues, and take that as the intent of the statute. That makes issues of identity an empirical matter, since it amounts to asking about human psychology.

    In that sense, most people I suspect would side with the OP (and would side with Kirk still being alive after being transported, and it indeed being the real Kirk).

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  19. Coel, your second “heap” scenario would seem to imply Kirk’s death to me. The first one is currently undetermined: biology would tell you whether you killed Kirk or not, assuming one could do the experiment.

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  20. Hi William.

    I broadly agree with you on the philosophical issues, though I would express some things rather differently. For example, instead of saying that both Kirks are “the real Kirk”, I would say that questions like “Which is the real Kirk?” are misguided in this context. In Wittgenstein’s terms, I’d say that this is a case of language “going on holiday” or “idling”. Such questions make sense in certain ordinary contexts, such as cases of mistaken identity, e.g. which is the real Kirk and which is the look-alike (who is actually different from Kirk in significant respects)? But in the current context it’s been stipulated (or so I take it) that the two Kirks are identical in everything that matters, including personality, memories, etc, so there’s nothing left to settle. There only seems to be something to settle because we tend to have an essentialistic sense of identity, which makes us feel that there is some essence of Kirkness which may or may not have passed to the copy. Plus, our language confuses us: since such questions are meaningful in other contexts, we assume we can sensibly ask them in this context too.

    While I’m slightly uncomfortable with your use of the word “rules”, I do agree with you that spatial continuity is not essential to our sense of identity. We have no problem imagining that we’ve been magically teleported to another location. We might object to such scenarios on the grounds of physical impossibility, but we’re not inclined to object on the grounds that “it wouldn’t really be me”. I think what violates our instinctive sense of identity in the ordinary (destructive) Star Trek transporter case is the fact that the original is physically taken apart, as we associate that scenario with death. In a case of copying, our essentialistic sense of identity is violated, no matter how the copying occurs.

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  21. There’s a more technical point on which I would like to disagree with you, William. (And I hope splitting my comment over two posts to avoid the word limit isn’t a violation of the rules!)

    I think your talk of unique identifiers is unhelpful, and eventually causes you to ask a misguided question about which animals’ brains work in that way. We can model reality in terms of identifiable persistent objects without assigning each object a unique identifier, and I very much doubt that the brain uses them. Even your computer database doesn’t absolutely need them. The mere allocation of a record to each person is enough to create an identity. Unique identifiers are helpful with computer databases, because, once we have one of those in hand (e.g. reading it off an ID card), we can uniquely identify the right record. But the human brain doesn’t have such a unique input available. We typically have to identify people (and other objects) fallibly from their appearance, voice, etc. We can think of this as analogous to searching the database for the record which best matches whatever identifying data are available. A unique identifier is no use in that case.

    Once we abandon the idea that identification involves a unique identifier, it becomes unclear what it would mean to ask which animals have the capacity for identification. Would we count an animal that can keep track of a prey that it’s hunting (remembering things about the prey from moment to moment), but starts afresh after a period of not observing the prey? If the fact that it can’t re-identify the prey after an interval is taken as determinative, then how long an interval do we count? I think that any question of this sort is fuzzy, and the boundary between animals which do or don’t have such a capability will be a fuzzy one, and very fuzzy if we ask the question in broad terms. Looking for some sharp distinction in the brains of animals is probably a mistake.

    Computer analogies can be very useful in thinking about how the mind/brain works (I often use them myself) but we must also beware of them. The brain works in some significantly different ways from our familiar computers, and simplistic computer analogies may lead us astray. The vast complexity of the brain’s software (I use that term broadly) means that our simple models can map onto reality in only very fuzzy ways.

    Incidentally, I don’t really see these as “neurobiological” questions. I would say that in such discussions we are modelling the brain at the “software” level of abstraction.

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  22. brandholm, well, “the self” is a high level description of certain patterns in the world, not an essence. So the answer to your question is tricky, and eminently empirical, but I doubt it changes the substance of my argument (with which you agree anyway!).

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  23. There are many interesting issues in play here, but I think I’m going to make a couple more replies and leave the rest to stand. First about turf warring — I wish we could just get past this. Is it science or philosophy? Well, it’s both. I really don’t see any clean distinction between the two. Scientists do philosophy all the time, even if they don’t realize it. Every application of Occam’s razor is a philosophical assertion, and no principle is more central to the scientific method than Occam’s razor. Philosophers also very frequently do science without realizing it — they often make scientifically testable empirical statements, sometimes justifying them by appeals to intuition. As I see it, the turf warring is largely an artifact of the separation of science and philosophy into different departments in universities. Once upon a time science was known as “natural philosophy”, and if we continued to think about it that way, we would be better off. It is useful to make a distinction between conceptual issues and empirical issues, but neither science nor philosophy can progress without paying attention to both types of issues.

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  24. P.S. After reading the OP again, and some of the comments, I would say my disagreement with you is greater than I previously thought. I originally read the OP rather quickly on my smartphone, and didn’t notice that you were using your “neurobiological” hypothesis to support your philosophical conclusion. I agree with Arravis that we don’t need that hypothesis. (Which is just as well, since I think the hypothesis isn’t true!)

    Also, you wrote: “Thus if I make a fist, it remains the same fist as long as I keep my hand clenched, but if I open my hand and then clench it again, it becomes a different fist.”

    As far as I’m aware, we don’t normally talk about fists in this way, and I don’t know how to make sense of it. It seems to me this is another case of language “idling”.

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  25. >>It seems impossible to imagine a world that is not divided into things. However, the world of modern physics is just such a world. In modern physics, objects are merely clusters of matter and energy that cohere for some period of time — they have no deeper reality.

    I always wonder exactly what kind of “deeper reality” people who make this kind of argument think has been disproven by physics.

    I mean, typical examples of “things” that one might expect the world to be divided into might include cats, dogs, trees, ships, etc. You don’t need to be a modern physicist to know that all of these things are composed of many smaller parts that can be separated – bones, muscles, organs, planks of wood, etc. So when modern physics comes along and discovers that even these smaller parts are themselves “clusters of matter and energy that cohere for some period of time”, exactly what ‘deeper reality’ has been debunked?

    Do you think, for example, that people were expecting to find a microscopic tag attached to every part of a cat saying “I am part of Tammy the cat!” Or did you think people were expecting to find – in addition to a cluster of cohering matter and energy – a cat-shaped container holding all the matter and energy together as a single object (like a bunch of dough contained in a cat-shaped cookie-cutter)? I don’t think any serious philosopher has ever held such a view (think about how ridiculous these views are when applied to something like a ship), so there isn’t much interest in using physics to refute it. To repeat, then, when you say that modern physics shows there is ‘no deeper reality’ to things beyond being mere clusters of matter and energy, exactly what ‘deeper reality’ are you denying the existence of? It’s impossible to say whether modern physics has refuted such a ‘deeper reality’ unless you tell us what the heck you’re talking about.

    Maybe you think there’s no ‘deeper reality’ to objects like cats and dogs in the sense that appealing to such macroscopic objects has no scientific explanatory power. Perhaps we can dispense with them just as we’ve dispensed with the use of final causes to explain the movement of inanimate objects. But this seems patently false, since we appeal to such macroscopic objects to explain natural phenomena all the time (e.g., how did that round cluster of twigs and mud get into that tree? The best explanation is probably that a bird built it.) This, of course, is a rehash of the reductionism argument that has been discussed on this website several times, so I won’t go any further.

    I don’t object to trying to use science to solve classic philosophical problems, but it seems to me that the eagerness to appeal to science and neglect the traditional methods of philosophy often results in ignoring really basic issues.

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  26. To Coel, I liked your first example. In a more extended discussion of the transporter problem I was planning on using the same line of questioning. Our “instincts” seem to hinge on a space/time continuity, which you can really narrow in on. Also which portions (i.e. the minimum material that must remain). Eventually it would become an experimental question, as such I think it is one of strongest logical challenges (meaning not easy to answer) to the transporter thought experiment.

    Regarding the second example I think it depends on what you meant by “heap”. I tend to side with Massimo that the way its sounds, biologically he would be dead. However if you meant that it preserved atoms in the exact same arrangement, thus creating a sort of stasis, which is then updated with changes found when avatar Kirk ends his mission and beams back up, then I’d say alive.

    To Massimo, yes I’m just checking for potential edges and weak spots where additional evidence and thought might become necessary in the future. As it is now, there is no evidence that could give someone sufficient reason to doubt (y)our position.

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  27. I’m going to weigh in further on the Kirk Transporter scenario, beyond my previous comment that it’s an entirely different scenario than the ship, and also only tentatively connected to the other issue(s) Bill notes.

    They’re two different Kirks. They don’t become two different Kirks from being in different social situations, they’re two different Kirks from the start.

    The one “acted upon” by being beamed somewhere is in some slight, quantum-mechanical way, different. Transporter scenarios as thought experiments always seem to implicitly assume Newtonian mechanics, wrongly.

    And, since we have (I’m with Massimo) no testable information of multiverses, strings, etc., and, even if we did, the other multiverses would be splitting from ours due to quantum mechanics and thus still subject to quantum mechanics, transporter thought experiments, while logically possible as thought experiments, are scientifically impossible as actualities. Coel and Labnut will again disagree with me on QM, but, they’re simply wrong, as I see it.

    ==

    Now, to Bill’s other issues.

    Ethology and related issues already DO, with some tentativeness, answer your “what other species” question. The old “mirror and spot,” while not perfect, is still a sold starting point and has been around for some time.

    As for species that are of a certain level of socialness and intelligence as well (none of E.O. Wilson’s ants!), looking at the question of personal identity, field research a la Goodall, Fossey, etc., answers “how” this plays out with primates, like humans having a selfhood based on embodied cognition.

    As for the “how” of consciousness as embodied cognition arises? Per my essay, neuroscience today is in the Early Bronze Age, and at least right now, has little to tell us. Per Ryle and his “ghost in the machine,” or Dennett (and many others) with no “Cartesian meaner,” my extension of that to volition, etc., we will likely never be able to point out certain processes, and thus never point out certain brain actions, etc., that say “ahh, there’s where the self is created,” or anything close.

    Pointing to the “inferior temporal lobe” also seems to founder on the reef of confusing ship-identity with person-identity. (And, yes, I like extended puns like that.) The IFL is indeed involved with how people identify objects. But, that’s again not the same thing as the personal identity issue that the Kirk-Transporter thought experiment is supposed to be about. And, the mirror experiment for animals, even, is in part designed to find out, by seeing if an animal recognizes itself as an individual object, to then go on to see if it has a concept of selfhood.

    Getting back to Ryle (and Aravis can thank me later!): In part, what we have here is a category mistake.

    Other related thoughts: Per Richard, on memory, I think you’re pushing computer analogies way too far on human memory. Human memory is not discretely stored like computer tapes/hard drive bits, it’s regularly “rewritten” by our own minds, and more. To the degree you base your ideas of identification on this analogy, they don’t have a lot of strength.

    Finally, Richard, thanks for bringing some language thoughts, and specifically, your idea of “idling,” to the table.

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  28. This is one of the best posts I’ve seen on SciSalon.

    Your approach reminds me much of the Naturalized Epistemology Program. Rather than a-priori/conceptual/modal analyses to difficult concepts, we ought to study the mechanisms that produce or underlie them. This involves both neurobiological and systems level explanations.

    The science of ‘knowledge’ and ‘identity’ gives us a better understanding of their quirks than mere conceptual theorizing. Same thing with the problems of ‘mind’, but I would bracket phenomenal consciousness as uniquely philosophical. Sometimes, science underdetermines our metaphysics (think of the dual slit experiment and conflicting accounts of quantum mechanics).

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  29. The issue of ‘Ship of Theseus’ is the nutshell of this identity issue which is the central point in physics, math, biology, and in philosophy. Thanks for author to bring it up. Yet, I do not think that author resolved this issue, and I do not believe that brain states or structure is the pathway for getting the answer. This is a physics and a math issue; that is, it must be resolved in physics and in math.

    Every entity in this physics-universe can be uniquely identified with four tags. I am using the most elusive entity (the quantum particle) as example.
    One, the skin tag (Sk, the pilot wave envelop for the quantum particle), it is a membrane for a single cell.
    Two, the spatial tag (Sp, its location, momentum (energy, mass), spin, etc.)
    Three, the temporal tag (Te, its time coordinate)
    Four, the entropy tag (Et, its life-history in processes). When I put my hand out and pull it back to the original position, I have a different Et tag although all other three tags are not changed.

    That is, every entity in this physics-universe can be identified as {Entity = F (Sk, Sp, Te, Et)}. For a new TV, it becomes a ‘refurbished’ TV after a repair (with a new Et tag). In fact, the ‘Tienzen Gong’ of yesterday has a different ID-tag from the tag of today. However, most of my friends identify me with my Sk tag only. However, after a long period (20 years) of separation, many of them will see me as a different person as the Te and Et (aging) tags become noticeable.

    Thus, the issue of ‘Ship of Theseus’ is only a ‘perceiving’ issue. When the first plank was replaced, it is a different ship in the physics-universe. Of course, the entire reconstruction with the old planks can be viewed as the same ship if only the Sk tag is used as the ID-tag. There is no paradox about this ‘Ship of Theseus’ issue, which is totally a perceiving issue.

    This identity issue is the ‘key’ for consciousness which is significantly different from ‘intelligence’. Yet, recently Max Tegmark and Tononi proposed an “Integrated Information Theory (ITT)” as a model for consciousness, and it is completely off the target, as the consciousness is completely different from the intelligence.

    Consciousness is all about the distinguishing the entities while the intelligence is all about the information processing. I have discussed this in more detail at http://broadspeculations.com/2014/06/01/consciousness-much-ado-about-almost-nothing/#comment-3016 .

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  30. “Pointing to the “inferior temporal lobe” also seems to founder on the reef of confusing ship-identity with person-identity.”
    the occipital-temporal border is where “face cells” are found and where, when damaged, prosopagnosia ensues. How is the wrong? Seems like an excellent place to start.

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  31. You had me at “… and it (Tegmark Tononi) is completely off the target”.

    Like the 4 categories, especially “skin”. boundaries are a critical part of our perceptual system, not so much physics. We tend to “chunk” the environment beyond what’s there. think of the boundary for a river or a cloud.

    An additional point for discussion is the mental concept of “essence”. The ship has an essence, which we can think of as a center of mass, separate from its components. We attribute “essence” to lots of things: people and special objects. Original works of art are an example. Why are they more valuable than excellent copies?

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  32. Hi Massimo,

    The first one is currently undetermined: biology would tell you whether you killed Kirk or not, …

    That sounds as though you have no *philosophical* objection to saying it is still the same Kirk if you instantaneously replace every atom. Biologically, isn’t it obvious enough that it would make no difference and that he’d still be alive?

    (Physically, of course, this can’t happen, but this is a thought experiment about the human psychological concept of identity so that is irrelevant.)

    Presuming that you’re ok with a transporter instantaneously replacing every atom, why would you not be ok with that transporter instantaneously replacing every atom *and* moving the ensemble 1 metre to the left at the same time?

    I guess another question is whether it’s the same Kirk if the transporter transports all the *atoms* instantaneously, along with the Kirk pattern, rather than assembling the pattern elsewhere with new atoms.

    Hi brandholm,

    Regarding the second example I think it depends on what you meant by “heap”. I tend to side with Massimo that the way its sounds, biologically he would be dead.

    That heap of atoms would of course be dead, but “Kirk” would have been transported, and thus would still be alive though instantiated with new atoms. Once he’s beamed back he has his old set of atoms again.

    Hi Bill Skaggs,

    Is it science or philosophy? Well, it’s both. I really don’t see any clean distinction between the two.

    Agreed, well said!

    Hi Socratic,

    Coel and Labnut will again disagree with me on QM, but, they’re simply wrong, as I see it.

    No, I would agree that Star Trek transporters are unphysical, but (as above) I don’t see that that prevents such thought experiments being useful in elucidating concepts.

    Hi Iqrvy,

    I always wonder exactly what kind of “deeper reality” people who make this kind of argument think has been disproven by physics.

    Platonic essentialism perhaps?

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  33. Coel, as you should know by now, my philosophy is informed by my science. Hence my objections to uploading and the like. I see no inconsistency in invoking empirical evidence within a philosophical argument whenever needed.

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  34. jkubie,

    “An additional point for discussion is the mental concept of “essence”. The ship has an essence, which we can think of as a center of mass, separate from its components. We attribute “essence” to lots of things: people and special objects. Original works of art are an example. Why are they more valuable than excellent copies?”

    That’s a rather magical conception of ‘essence’. I have understood essence in a more logical sense (in a sense more related to logic): the essence of something is just its logically necessary and sufficient conditions. To illustrate, if Aristotle was right and man is the rational animal, then both rationality and animality are parts of the essence of man, and together they are the essence of man.

    As to what makes original art more valuable than a copy, I doubt this has anything to do with etherial essences. It’s just a preference of the marketplace; would you rather have a painting made by Picasso himself or an exact copy of a Picasso made by a hobbyist in Minnesota? For whatever reason, we all want the former more and this explains the difference in value. Actually, ‘difference in value’ just means a difference in how much something is wanted. But like ‘essence’ we sometimes speak of value as if it were a ghastly thing, floating through space, getting entangled with some things but not others, like some supernatural seaweed.

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  35. “essence” isn’t a magical property, its a mind property. there are many examples, some offensive. Would you wear a sweater if you were told that Hitler had worn it? What about a house owned by a mass murderer? This seems more than superstition. As for works of art, clearly the value is due to the market. But why? Is it just a scam or something more? Do we feel, in some fashion, a direct connection to the artist, his/her esssence, in and original? Getting back to Bill Skaggs’ notion, the original has gone thru a continuous trajectory through time and space, from in front of the artist to its current location. That seems related to both identity and essence.

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  36. But does the brain really use a concept of identity that has a unique tag, an identifier, that separates all the field information in a memory record, packaging it for recall? Cognitively opaque or not, I don’t understand how such unique identifiers are compatible with the fallibility of human memory. Computers do use them which is why they are practically speaking infallible in recalling information, unlike people. I don’t understand how a unique identifier’s effectiveness is impaired by circumstances, yet current circumstances affect the content of real “memories” in people. Further, I’m not getting how identifiers and fields engage in the memory reconstruction process at all. Is there really a set of blank fields that the brain fills in by guesswork when a memory is called up?

    If I try to picture memory formation, i can’t keep myself from placing the start in the sensorium. All the neurons processing information (starting not just with the optic nerve, but all the sensory neurons, even the pain receptors) in a persistent pattern and this pattern is first registered as part of short-term memory tracking the environment. The stronger patterns get stored in long-term memory. I suppose the repeated firings of those neurons prompt permanent physical changes such as increased numbers in brain areas specializing in different perceptions. Transient aspects of the experiences do not survive. Whenever the imagination recalls a memory thus only the most salient aspects are truly available. Without all the bare facts, the imagination fills in using the same capacities and process used in filling in imperfections and gaps in the current sensorium. But like most people I am profoundly ignorant of how brains actually work so maybe this is nonsense?.

    In this picture, though, it seems more natural that people would be able to devise notions of categories or genres of objects, which are something like a block of marble. People do, as infants especially, confuse individuals things. It is correction of errors by interaction by impels an identification of separateness. A door becomes separated from the background by the way it feels when it swings when pushed. A doorknob becomes separated from the door by the way turning it affects how the door swings. In the identifier system, it seems that you would basically have to have a brain structure that had a slot for identifiers, then slots for fields.But if people have this kind of template for data storage, why do they have difficulties in grasping concepts like structure, system, process, as my experience says they often do? They can have identifiers and fields too. I’m not sure that people really have a memory of “hurricane” instead of a memory of the explanation they were given about “hurricanes.” I’m not at all sure that identity (especially as object-permanence) is really applies to recall of the meanings of words, as opposed to the everyday memories of experiences showing that objects have identity.

    Personally, I can’t really believe transporters make a perfect copy of Kirk, which is why I’d never get in in one. As for the ship of Theseus, there is no way to make the original ship from the worn out parts, so there is no perfect copy there either. I think these problems aren’t as compelling when you accept there are no perfect copies?

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  37. I didn’t address the Ship of Theseus in my earlier comments, and I’d like to do that now. I would say that, if we take the question “is it the same ship” as a substantive question, then this is another case of language idling. We’ve been given all the substantive facts about the case, and there doesn’t seem anything substantive left to settle. At most there remains a linguistic question about whether it’s appropriate to use the expression “the same”. Even answering the linguistic question is difficult without putting it into some context.

    Let me illustrate by giving an example context. Suppose there’s a one-time tax to be paid on each ship. Theseus paid the tax when the ship was built. When he returns to his home port after 10 years away, the harbour master demands he pay the tax again, because every part of the ship has been replaced, and so (he claims) it’s not the same ship. Now there is something real at stake. Theseus may have to pay some money. What makes it true here that there’s something at stake is the existence of a law (or more generally a human convention) that depends on whether we say it’s “the same ship”. (I assume the law says nothing more specific than “the tax is to be paid on each ship”, and that no special convention has been established as to how to handle this situation.) In this case a linguistic question is turned by the context into one with practical consequences.

    So how do we answer the linguistic question? We can’t limit identity to absolute identicality, or objects would cease to be called “the same one” the instant they lose or gain a single atom. On the other hand, we can’t extend identity regardless of any changes, or Thesus could return with a super-tanker that retained only the name-board of the original ship, and claim it was the same ship as the trireme he left port with! Language generally can’t be applied in these sorts of absolute or formulaic ways, but depends on making reasonable, practical, non-formulaic judgements. I think most reasonable people (and probably a judge) would accept Theseus’s ship as the same one if it had undergone only genuine repairs and modest changes, leaving the overall design much the same. They would be particularly likely to deny it’s the same ship if it looked like there had been an intent to get around the law.

    The way the scenario is usually presented, I guess it’s reasonable to read into it that Theseus has just made ordinary repairs, and so I don’t have a problem with someone saying simply that it’s the same ship, as long as we understand that no substantive fact is being given. The point should just be that, given a reasonably ordinary context, this seems pretty consistent with how we would usually use such language.

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  38. Who will try relating this to Quine’s “Identity, Ostension, and Hypostasis”? It doesn’t comment on brain-stuff, so no doubt many would dismiss it as “folk identity”, but it’s more sensible than all this neuroscience speculation. See Stuart Firestein, “Ignorance,” and Raymond Tallis, “Aping Mankind.” Both these authors are, unlike most (all?) commentators here, actual neuroscientists!

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  39. OK, down to what the honorable Bill Skaggs seems to have wanted to say, as far as I can comprehend.
    Forget the ship and Hollywood. As I said, Quantum Identity is strong, and makes those time honored examples impossible.

    The better model is category theory.
    Category Theory is about diagrams. Category Theory has been increasingly replacing advantageously Set Theory. It’s not only because it does not have to ponder the nature of objects, elements, sets.

    Category Theory was long derided as “abstract nonsense” and “diagram chasing”. But it gives very deep, powerful theorems. They should translate directly into… neurology.

    When are two diagrams equivalent? When are they IDENTICAL? Cantor defined as of the same cardinal two sets in bijection. Category Theory defines as identical the same drawing. Say: A>B>C>D>A is the same as E>F>G>H>E.

    When are two diagrams identical in category theory? When they are modelled by the same neuronal network. And reciprocally!
    I agree that, to have a theory of the mind, we need to have a notion of identity. What better place to start, than the most basic of maths? Especially if it looks readily convertible in neural networks.

    In conclusion, two objects are identical, neurologically speaking, if they are so, in category theory.

    Ah, in other news, and to answer a point of Bill: whether a rock can be truly isolated is an open problem, experimentally speaking. According to the theory of gravitation of Einstein and company, no (because the rock is immersed in spacetime, which is about gravitational waves, which ought to appear in a particular effect, the graviton).
    http://patriceayme.wordpress.com/2014/10/24/quantum-identity-is-strong/

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  40. “Both these authors are, unlike most (all?) commentators here, actual neuroscientists!” Um, not sure about the others, but Bill and I are neuroscientists.

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  41. Since we’re approaching closure here, I’d like to sum up insofar as I can. I’m grateful for all the comments. A few perhaps have missed the point, but many have raised issues that I need to think more about, and even those that missed the point have made it clear that some things need to be explained better. Some of the comments I don’t fully understand and will need to explore.

    Let me revisit very briefly what I was trying to accomplish. Identity, as I am dealing with it here, is not by any means an abstruse thing. It is a practical concept that we apply hundreds of times every day, any time we identify something as the same thing we have encountered at some point in the past. The philosophical underpinnings of that concept are certainly of interest, but also of interest are the cognitive rules that govern the identification process. I have suggested that thinking about the cognitive aspects can help to inform our philosophical understanding. What interests me even more is that neuroscientists and psychologists have not paid sufficient attention to the cognitive-biological mechanisms that underlie the identfication process. I don’t believe there is any chance of understanding something as complex as “Theory of Mind” without first having a basic understanding of the way we represent things as unique individuals.

    Perhaps I should stop there, but I’ll go on to point out that not all questions about identity have the same status. In most real-life cases when we ask about the identity of something, the answer is a matter of objective fact. We implicitly presume that identity implies continuity in space, time, form, and substance, and we are asking whether those sorts of continuity are present. Suppose for example that a tornado strikes my town while I’m at work — I head home and see a pile of rubble, and ask “Oh my God, is that my house?!” What I’m really asking is whether that pile of rubble is historically continuous with the house I left this morning. That’s either true or false. However the facts that make it true or false are almost never fully available to me — I’m almost never in a position to trace every point in the continuous history, and therefore am forced to rely on various types of circumstantial evidence.

    But now consider the Ship of Theseus — I ask whether the ship continues to be the same ship after all its parts have been replaced. Here, even though the question has the same form, I am not asking about a matter of objective fact. I know all the objective facts. I am asking about the concept of sameness — about how to apply it when continuity is compromised.

    Now let’s consider the question of mind uploading — of whether a mind uploaded onto a computer can be the same mind that was previously present in the body. Here it isn’t entirely clear which of the two categories the question falls into. To people who believe in a soul or something equivalent, the question comes down to whether the soul moves from the body into the machine. If souls are objectively real, then this is a matter of truth or falsehood. But to the majority of philosophers, I believe, the question is more like the Ship of Theseus. It is a question about the concept of sameness, and therefore ultimately comes down to a matter of personal preference, not a matter of objective fact.

    To most philosophers, I believe, the question about the Ship of Theseus is interesting, and the question about mind uploading is even more interesting. To me, the question about what happens when I identify my house is more interesting than either of them.

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  42. I wish I could edit the comment I submitted a few minutes ago, but since I can’t, let me add that I only now realize that I was essentially repeating some of the things that richardwein wrote above Unfortunately I didn’t read his comment until after I submitted mine. Sorry!

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  43. @richardwein I think you’re entirely right in identifying this is a linguistic issue — though admittedly I would say that most philosophical problems are linguistic issues.

    As mentioned earlier, identity fundamentally isn’t; it exists strictly in conceptual space (and more specifically, it exists differently in the various conceptual spaces of various brains). As such, questions of identity are not scientific questions unless we want to make them scientific questions — and I think the science-talk here obscures rather than illuminates insofar as it implicitly suggests the existence of some sort of objective answer.

    “The same X” necessarily functions in a specific linguistic context in a specific illocutionary way in a specific form of life, and I don’t think that context is nearly as generalisable as we might like — like all *things* metaphysical, any conception of identity is going to emerge linguistically from a particular experience, and the language only manages to avoid being nonsensical to me or you insofar as we share the form and experience of life from which it emerged. So the more useful question(s) with regard to identity as far as I see it isn’t so much “Is this identical or not?” as it is “What does this person’s particular invocation of the property of identity highlight?” or “What does this person’s particular invocation of the property of identity obscure?”

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  44. Given the abundant amount of comments, this point was probably already made, but I want to make it anyways. I think the author is confusing two issues here: how the concept of identity is realized/implemented in the brain and what is the exact nature of personal identity. The former provides a neurobiological/computational explanation of how we monitor, construct, and track our personal identities. The latter is about finding a principled manner in which some person X on T1 is the same as person Y on T2. All the former could really do is explain how I typically keep track of myself, but it doesn’t explain what makes me from yesterday the same person today. After all, the former account seems to say that I recognize my personal identity by tracking episodic memories. This may be true as an epistemic account of how I recognize myself as the same person, but this can’t be treated as a serious metaphysical candidate for explaining the nature of personal identity; in fact it was already presented, but fell out of favor when the following objection was presented: Suppose someone suffering from amnesia fails to recognize his or her past self. It would seem that his or her present memory is discontinuous with his or her past memory. According to the said account, this lack of continuity means that person is not the same person from several years ago. But this can’t be right. John is still John even though he forgot who he use to be, because his current self is in continuity with his past self in other ways. In my opinion, the author’s account should be treated as an explanation for how our brain constructs a model of personal identity, rather than a serious account of personal identity itself. The problem here seems to be that the author thinks it should be treated as an answer to a philosophical problem that perplexed us for centuries.

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  45. “Hard cases make bad law.” Then, given the intimate relationship between law and philosophy, “Absurd premises make bad philosophy.”

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  46. @philonous13: If those two issues are really distinct, then you’re quite right that I’m confusing them, because I believe that they are really the same issue. I am not convinced that there is really anything special about personal identity. The arguments that I have seen about the specialness of personal identity don’t seem valid to me.

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  47. JKubie, quoting me, notes:

    “Pointing to the “inferior temporal lobe” also seems to founder on the reef of confusing ship-identity with person-identity.”
    the occipital-temporal border is where “face cells” are found and where, when damaged, prosopagnosia ensues. How is the wrong? Seems like an excellent place to start.

    Well, it is, if you’re trying to identify objects as objects.

    But, the inferior temporal lobe has nothing to do, or nothing special, at least, to do with issues of personal identity. And, that’s why it’s at the crux of what I see as a classical Gilbert Ryle category mistake. Unfortunately, in his last comment, Bill doubles down on that, when he says:

    @philonous13: If those two issues are really distinct, then you’re quite right that I’m confusing them, because I believe that they are really the same issue. I am not convinced that there is really anything special about personal identity. The arguments that I have seen about the specialness of personal identity don’t seem valid to me.

    Since Theseus’ ship doesn’t have consciousness (unless you’re a Jain), in my world, there’s a big difference. That said, Philonous wasn’t commenting on that, even, but on something narrower yet, namely:

    In my opinion, the author’s account should be treated as an explanation for how our brain constructs a model of personal identity, rather than a serious account of personal identity itself.

    I agree that that itself is a difference which makes a difference, but denying that it’s a difference isn’t at quite the level of a category mistake, unlike what I have pointed out that IS a category mistake.

    And, so, back to that.

    If we separate out Bill’s conflation of personal identity, and identity of objects as objects, into two separate items, in 20-30 years, neuroscience MAY have something important to say about personal identity that it hasn’t said to date. Or it may not. If it does have something important to say, it probably will be important but a few levels below earth-shaking.

    If we look at Philonous’ issue, this gets back to issues of volition, consciousness, etc. Neuroscience may help with the “deck-clearing” of telling us what questions we need to be asking, the “unknown unknowns,” etc. I think it has offered a few bits of insight already, via the Libet experiments and follow-up, on the aspect of volition, and how we try to define it, but on larger issues of what personal identity is, probably doesn’t have anything to contribute right now, except in guiding thought experiments about whether identity can be “transferred,” which Bill references.

    Answer to that? Starting with an embodied cognition version of consciousness, the answer is no, if you’re transferring the “self” (if that’s possible), to a different “platform.” In short, Kurzweil needs to go blow up his drawing board.

    And, if Bill doesn’t see any difference between Philonous’ two issues, let alone between identifying things as objects, and personal identity of things with a consciousness or self, then we are at the winding down point.

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