But I guess considering what is a "significant difference in different gravitational forces" would embark us too far astray — javra

I would say it would be difference great enough to make a significant difference to biological "age".

... and in the realm of metaphysical possibility, which this thread is in part about. — javra

We don't know what is metaphysically possible, and we only know what is physically possible given the assumption that our understanding of natural laws is correct and comprehensive.

Yes, if the theory of relativity is in fact correct it operates everywhere. Since the different gravitational forces would not make for much of a difference, and it may well be impossible for objects to travel at anywhere near the speed of light, such thought experiments as would allow for huge differences in the progress of biological processes, and hence significant differences in aging probably remain in the realm of fiction or fantasy.

I agree that it is very, very hard to deal with all the complexities of any interesting question. The trouble is that the devil is almost always in the detail, so I'm reluctant to ignore complexities, even if it isn't possible to sort them all out. A grand simplification always gets me going, I'm afraid. Perhaps it is better to think in terms of focus rather than simplification and then it is easier to at least acknowledge complexities. — Ludwig V

It doesn't seem that there are the same complexities (although determinacy is another matter) when we think about the identity of everyday objects as there are when we attempt to address human identity. So, it seemed to me a good plan to start with the simple cases and then work towards understanding the complexities of human identity built upon the relative simplicities of object identity.

Just as an example, a deontologist that believes that one does not have the duty to uphold the rights of a person who is engaged in the violation of other peoples' rights, which is usually called a principle of forfeiture, will have no problem going to war with people that have forfeited those rights. — Bob Ross

Why would this not apply to young people who are conscripted (if not to voluntary soldiers)?

Right, but what I was angling at is that the age of the Universe would not vary depending on where you are in it; there would seem to be a sense in which there is a current state of the Universe. And in general, when we talk about the age of anything, existing things which came into being earlier than other existing things are considered to be the older. On this criterion a daughter could never be older than her mother while they are both still alive, although of cause the daughter could live to a greater age.

As concerns objective time, however, the same dichotomy between a relativistic time and cosmically absolute time will present itself. With all indications now pointing to time being relativistic rather than absolute. — javra

And yet the claim is that the Universe began around 14 billion years ago. Time perhaps does not exist apart from change, and when you think about it the general durations of processes of change probably don't vary that significantly because no macro-objects are travelling at anywhere near the speed of light, and they also are not subject to massive time variations due to gravity either.

If we say there are three types of time — historical time, chronological time, and biological time —, the main character is younger than his daughter in all but historical time. — Lionino

I would say there are historical (Earth or chronological) time and phenomenological time. If biological processes would be slowed down, reduced to almost zero at near light speeds, what would a person on a craft travelling at such speeds experience? Such travel may well be physically impossible in any case, but allowing for the sake of argument its possibility, I can only imagine that during such a journey, even if it lasted a thousand years, the passengers would experience almost no time, or even no time at all, if travelling at light speed.

So, yes if that were possible then the main character would be biologically younger than his long dead daughter. On the other hand, since Earth time is really what counts for us, we would say he has been gone for a thousand years, and is thus one thousand plus years old, even though relatively unaged.

I'm not sure what exactly you have in mind by "time paradox". If travel at the speed of light were possible, someone might not age much or even at all on a thousand-year journey, but she would have endured for a thousand years if the temporal context we are considering is Earth time or even (perhaps) experiential or phenomenological time.

My take is that what is actually possible is what is physically possible, with reference to this world. If there were other worlds where what is impossible here were possible there, then that possibility might be categorized as metaphysical possibility (although we could say that the scope of the category of physical possibility has thus been expanded instead).

What is logically possible is anything that does not involve self-contradiction. Perhaps it could be said that there is a valid category of metaphysical possibility distinct form the category of physical possibility only in the context of positing that there might be existences which are not physical; that is not constrained by any physical law. Would they be constrained by metaphysical laws? Whatever the answer to that might be it seems impossible to imagine that they would not be constrained by logic.

(Adaline mysteriously stops aging due to an accident and her daughter grows older than her). — javra

Should we count age as being the time of duration or physical change? Adaline has endured for a longer time than her daughter, regardless of whether her body has continually "aged". So, in durational terms she is always going to be older than her daughter, and since the very meanings of 'mother' and 'daughter' presuppose that the mother exists antecedently to the daughter, then to say that the child could be older than the mother would involve a logical contradiction.

I think as a society we would, hopefully reluctantly, accept the sacrifice of the child, just as societies generally accept young people being sent to war, and suffering torture and death in order to protect mere national sovereignty, or even just to satisfy political affiliations, not to speak of societal annihilation.

Yes, all that...human identity is complex...but to simplify the question: what is it that makes any object or entity an object or entity? Is it an object or entity in its own right or only because we choose to count it as such?

Well, what matters most to me is that, so far as I can see, there's nothing to rule out the possibility and no positive evidence to establish impossibility. There is a common belief, dear to all of us, that each individual person is unique and irreplaceable - and the discovery of DNA seemed to give a physical basis for that belief. But that it seems to me to be an article of faith, though there is the identity of indiscernibles to fall back on. — Ludwig V

I could respond that, so far as I can see, there is nothing to rule out the impossibility and no positive evidence to establish possibility. I would add, as far as I am aware, there are no documented examples of any two objects being indistinguishably identical (even leaving aside the issue of occupation of different spaces).I think it is articles of faith all the way down, so you'll get no disagreement from me on that point. Perhaps we should augment the principle of the identity of indiscernibles with another principle: the indiscernibility of identities.

—

Well, I don't see why we need to rule that out as impossible. It may be very unlikely, but unlikely things do happen. And we'll never check enough leaves to establish an empirical possibility. — Ludwig V

I haven't ruled out its being possible, nor do I rule out its being impossible: we just don't know, which is what I've being trying to get across.

The difference between a kind and an individual is logical, or if you prefer grammatical, and not to do with substance. — Banno

There are individual or particular kinds just as there are individual entities of particular kinds; so, I'm assuming you're referring to the obvious logical difference between type and token or general and particular, and the fact that individual entities may be objects of perception, whereas individual kinds are objects of judgement.

I'm well aware that we cannot speak about the nature of what lies outside the scope of our experience and judgement. So neither of you seem to have carefully read and considered what I've been saying, which was in no way contesting this obvious truism.

What their existence might be outside of any perspective is meaningless and unintelligible, as a matter of both fact and principle. — Wayfarer

Yes, but the judgement that that they may have an existence outside of any perspective is neither demonstrably false nor unintelligible. You seem to be trading on the obvious truism that all our judgements are mind-dependent to draw the unwarranted conclusion that all existence must be mind-dependent. Existence and judgement are thus unjustifiably conflated

Yes. But you inadvertently run into the oddity about the Identity of Indiscernibles. If you know you have two objects in front of you, you know they are not identical in all respects. The only way this problem could arise would be if you knew about two different appearances of the same object, which may not be both in front of you at the same time. We know how to cope with that in practice, but I'm not sure that logic does. — Ludwig V

I think I get what you're saying—we could not have two identical objects in front of us because they would have to be occupying the same space which would seem to be impossible. My example of two leaves was more modest—if we had two leaves that looked absolutely identical to each other and no amount of measuring or examination including microscopic visual examination, spectroscopic analysis or whatever could reveal any differences, then there would be two possibilities: either our measurements and examinations are not fine-grained enough or the two leaves are identical in all respects except in regard to occupying the same space.

I would be prepared to wager that there never have been any cases of two such identical leaves or any other kind of object—although of course I could be mistaken. In any case, the two possibilities outlined above entail that absolute identicality could never, even in principle, be established, because finer measurement and examination which at any given time were beyond our capabilities could always reveal discrepancies between the two once they become workable.

Also, it is uncontroversial that no object would remain unchanged across time—but we do speak of "the same object" and at the same time acknowledge that any object changes to greater or lesser degrees over time, changes which may or may not be discernible to the "naked senses".

That's a big "if". I would have thought that the criteria most important to most people are social - and even when they are physical, they often also have social connotations. — Ludwig V

Really what I meant was that the criteria for establishing identity, in the sense of being able to recognize any entity, are physical. I agree with you that identity is mostly understood in social terms, but I think that is a different issue.

Changes in actual DNA are mutations and part of what's going on, but not, I would have thought a major part. At least, I had in mind the point that the way that DNA is expressed often depends on environmental factors. I have seen it is claimed that there is as much reason to say that we are products of our environment as products of our DNA. The idea that everything is down to DNA is an over-simplification that panders to our essential inclinations that DNA is the essence of what we are. — Ludwig V

I agree that the current understanding in genetics is that DNA can be expressed in different ways depending on environmental factors. It is thought that the way DNA is expressed determines, along with environmental conditions, all the forms of all the basic structures of our bodies, so it is not currently thought that everything is down to DNA in any absolutely rigid sense.

So, I would not say that DNA is the essence of what we are at all.

I won't argue with you. But isn't that an empirical claim, which it is difficult to impossible to refute. Isn't the real truth that the probability of an two leaves being identical is very, very small. But still, it can't be ruled out completely. When you get down to brass tacks, the same is true of DNA. — Ludwig V

Well, no two leaves can be absolutely identical just because they inhabit different places if nothing else. I know a couple pairs of identical twins, and I can tell the difference between them just by examining their faces. Also I believe that the current understanding is that even identical twins do not have absolutely identical genotypes, Whether we could ever find any two natural objects of the senses, whether biological or not, which were physically indistinguishable, is an empirical question I agree.

True.

n that case, then "Janus, at this exact day and time", would not exist if indeterminism is true and a different history had occurred. — Relativist

Yes, that certainly seems to follow, an alternative version of me would have existed instead. We have no way of knowing whether nature is determinsitic or indeterministic. It will always appear indeterminstic due to our inability to predict the future.

I think you're saying that the particular sperm/ovum combination that produced you is essential to being you. That combination is your historical origin, but isn't your subsequent history also essential to being you? This history would distinguish you from your identical twin, if you had one.

Is all your history essential to being you? If not, then how do you non-arbitrarily draw the line? — Relativist

I'd agree that one's entire history is essential to being exactly as you are at any time. If determinism
is true this could not have been otherwise. If indeterminism is true then you could have been different due to having encountered different circumstances throughout your life, but you still would have been you, a different you, just as the you next week will be a different you,

what bits could be changed and you would intuitively still consider yourself yourself. — Apustimelogist

I'd say that whatever changes don't kill you would not change your identity.

Then again, I don't think I identify all parts of my experiences with myself even though they are going on in parts of my brain... which are part of me??? — Apustimelogist

When we think of ourselves as experiencing something, don't we generally think that what we experience is other than ourselves?

Yes but clearly its not all essential and I think identifying myself just as a population of cells misses something in the same way that I don't think there is necessarily a single way of identifying or labelling or drawing boundaries within/around bodies or animals, other objects etc., even though doing so and thinking about it may have practical benefits or be interesting in some ways. — Apustimelogist

You can lose parts of your body that are not critical to your survival and still be a living, experiencing body. However, if you lose your eyes or lose your hearing you will not experience in those domains. A mere population of cells does not necessarily experience anything like you as an organism consisting of a self-regulating population of specialized cells does.

Roughly speaking the boundary of your being is your skin; it is natural enough to think of whatever is sensed within that boundary as part of oneself and whatever is sensed outside of that boundary as other.

I think there is at least a debate to be had about whether my dead body is me. Since I wouldn't be alive anymore. Maybe you would say it is me. — Apustimelogist

I would say your dead body is the dead you, which is very different than the living you, because it is no longer capable of internal self-regulation or of experiencing anything at all, either internal or external to it. It has become like any non-living object, but every particular non-living object is still thought to have a unique identity.

Are you the same person (same identity) today, than "you" were yesterday (or 20 years ago)? — Relativist

My answer to that would be yes, even though the body has changed, in fact changed all its cells a few times, those cells still have the same unique genotype, and the basic structure of the body is still usually recognizable all through its changes barring severe disfigurement.

What is it that undergoes the changes if not you? It's no different with each leaf that grows from a bud in more or less the same configurations as all the other leaves of the same type and then falls from the tree and withers away due to other organisms of decay.

Very much so, but I think there are still important questions about whether you would consider your phenotype the same as your identity. — Apustimelogist

Do you mean in the sense that I might think of my identity as consisting in being a mother, a scientist, an artist, a policewoman or whatever? Some people believe in an immortal soul and would say it is that soul and not their body that constitutes their identity.

If we don't accept the idea of a soul, then what alternative do we have but to think of the body as the manifestation of identity in the broadest sense, beyond considerations of profession and so on?

If each body has a unique genotype and phenotype, then DNA would be the most accurate way to establish bodily uniqueness, since differences of form can sometimes be hard to discern as can be the case with identical twins.

If you addressed the points I presented instead of making pointless claims about "my level" you might actually begin to do some philosophy. I don't believe in a flat earth by the way; do you? If not, on what basis do you not believe it?

By the way, it's not a matter of "worshipping experts" but of provisionally accepting that in their area of expertise their experience is more comprehensive and their judgements better informed than yours are. You go further than I do anyway in trusting their judgement, since you say you know Andromeda exists. And to say you know something, but do not believe it is incoherent.

Yep!

But I know they exist, because I read about them. — Corvus

Wrong...you know they are said to exist. And since there is no controversy regarding their existence among the experts, you have good grounds to believe they exist, You, curiously, have it all arse-about.

But then, any circumstances after conception that affect the development of the DNA will also result in a different entity existing. Surely? The development from DNA to person is not a railway track, but a path through rough country - to an indeterminate destination.

The fact that, on this account, the DNA is a necessary condition, but not sufficient, allows for the possibility that there are other conditions that could have produced the same result. No? — Ludwig V

If the criteria for establishing identity are physical, that is unique patterns or configurations of physiognomy then DNA would just be the most precisely measurable pattern. Whether those DNA patterns can change, as physiognomy obviously does would not seem to matter.

Take for example, oak leaves: every leaf has the same basic form (as every human does), but no two leaves are identical in every part. Each individual leaf grows from a bud and eventually turns reddish brown and falls to the ground where it will disintegrate over time. That is the whole usual story (some leaves may be eaten instead) of each particular leaf, but the details will not be exactly the same in any two cases,

But What function does this counterfactual serve? — unenlightened

To establish the facts?

"If i had been a soldier in Cromwell's New Model Army, I would have been having difficulty with the harsh discipline." - because "wrong sperm and egg". — unenlightened

Nothing I've said rules out imagining fictional scenarios. But I took this thread to be a critical examination of what it might be most plausible to think establishes identity. If it is the body, the physicality, that establishes identity, then you could not have been a soldier in Cromwell's army, but as I said earlier, if it is an immortal soul that establishes identity as is imagined in, for example, Hindu teachings, then you could have been a soldier in Cromwell's army.

This whole thread is a case of overreach by the thought police. — unenlightened

A somewhat hysterical overreaction, don't you think?

This is where the third person view helps. Since I wouldn't have existed, how would we know that the replacement wasn't you? Equally, then, how do we know that the proposed minor variation - even if it caused a massive difference - would have been at all different from me? It's based on the assumptions 1) that the DNA would have been different in some way that made a difference to the result and 2) that every difference is equally important. — Ludwig V

Don't you mean "Since I wouldn't have existed, how would we know that the replacement wasn't me?"?

I think it is uncontroversial from a science perspective that each sperm would produce a different genotype and hence a different phenotype (body).

On the other hand, if we were to adopt the "soul waiting to be born" scenario, then you could have been the same entity in a different body, if a different sperm had reached the goal first.

Right it was Achilles not the hare; I'm mixing up the stories.

:up: What you say there is a more succint way of putting it.

The tortoise will not have taken an infinite number of steps. The purported paradox consists in the infinite divisibility of the distance between the tortoise and the hare, with the claim being that if the tortoise is in front the hare cannot pass her in a finite amount of time. What is missed is that if the finite distance between the tortoise and hare is infinitely divisible, then so is the finite amount of time it takes the hare to pass the tortoise. Thus, there is no problem.

:up: We are very adaptable...and diverse...it seems.

Words come in the form of sounds and visual patterns. I can say any sentence I like to myself "silently"; I can hear it within, so to speak. Although I am also a visual artist, I cannot see internal images; meaning I cannot invoke a picture of anything like a photograph and examine it like I would a photograph. —except—when I'm tripping—then the internal images can be stable enough to examine them closely, but they don't seem to be subject to will, like the internal speaking of sentences is.

:100:

:cool: It's also a shame in a way, because it may signal the end of the conversation.

why you would presume that it is physically impossible for anything to be physically impossible, so to use your word, it's all just "philosobabble" anyway. — Metaphysician Undercover

I don't presume that all at all. It seems you misunderstood this

Presumably what is physically impossible is physically impossible — Janus

which was very badly expressed. I didn't mean to claim that it was physically impossible that anything should be physically impossible which would be a contradiction, The redundancy of expression there was just for emphasis; what I meant was that presumably some things are physically impossible.

That is to say that "physically impossible" is just a possibility, and therefore not really impossible. — Metaphysician Undercover

Physical impossibility is admittedly just a possibility for us; we are epistemologically limited, so we don't know with certainty whether anything is physically impossible or not. But it seems reasonable to think that some things are physically impossible given the way nature works. Fort example it may be physically impossible to transmute lead into gold, or for me to grow to be a thousand light years tall, or for that matter to travel faster than light.

traditional definition of knowledge is 'justified true belief'
— Janus

I'd say that belief presupposes knowledge, rather than knowledge being some condition on belief. In order to believe in something, you have to know something about that in which you believe. If you know no details about "it", you cannot rationally believe in "it". What I'm trying to say here is that we don't arrive at knowledge through belief, rather the other way around.

if we need to appeal to interpretation and belief (processing) and truth (correctness)
— Janus

You mean if the definition contains these aspects? — Hallucinogen

Belief presupposes knowledge in the sense of acquaintance; I must know you or know of your existence, for example in order to believe something about you. But if I want to say I know something about you beyond your mere existence or merely that you exist or what presents itself immediately to my senses, that presupposes that I believe something about you.

The radical skeptic will say that whatever I claim to be knowledge in the propositional sense is really just belief, because I could always be wrong, which would mean that what I had thought to be knowledge was actually not knowledge.

I don't understand your question: "You mean if the definition contains these aspects?". I am saying that "processing" is equivalent to interpretation and belief and that "correctness" is equivalent to truth.

What you wrote there reads to me like nonsensical philosobabble.

Presumably what is physically impossible is physically impossible, but it is also epistemologically (if not ontologically or metaphysically) possible that nothing is impossible; we just don't know. When I say "what may be" I am speaking from the epistemological standpoint which is that we may not know, or even, taking the radical position, do not and cannot know.

Taking the radical Humean position, we don't know with certainty that the sun will rise tomorrow, because the habits (laws) of nature might change, or the Sun might in the interim go into supernova, on account of some factor that we were unaware of in our understanding of solar physics. It follows that we don't know whether it is physically possible that the sun will not rise tomorrow.

Try using actual examples; I think it will help you to clarify your thinking.

Hopefully, it means that one might sometimes survive gene therapy. — unenlightened

Maybe the genotype can be altered, but then the result of the alteration would presumably be unique to the individual whose genotype had been altered.

I agree with you that the existence of any entity is enough to establish its identity; conversely, we must know its identity, in the sense of being able to identify it, in order to know it exists or has existed. Obviously, it is also true that the existence of an entity is easier to establish than its genotype. You would need to establish its existence first, identify it correctly, in order to be able to know you are testing for the genotype of any one particular entity.

In terms of counterfactual scenarios, though, I think @schopenhauer1 is correct to say that, in consideration of the genesis of any particular organism, any circumstances which would have produced a different genotype at conception, would result in a different entity existing.

For example, if the sperm that "won the race" in your case had not made it, someone else, not you, would have existed in your place; and such a thing may have happened if your parents began sexual intercourse just a few moments later or if they had been more or less energetic, and so on; just the tiniest variation could have resulted in your failing to have existed..

The definition I'd offer is that to know is to process information correctly. — Hallucinogen

The traditional definition of knowledge is 'justified true belief'; if we need to appeal to interpretation and belief (processing) and truth (correctness) then it seems that your definition is just the traditional one dressed up in different words..

I'm not sure where it goes from there. It seems reasonable to think that each organism can be identified by its particular genotype (apparently there are some divergences even in the case of identical twins).

That said, identifiability is not exhaustive of what we mean by identity (at least in the case of humans), so perhaps we could say it is necessary to establish, but not sufficient to explain, a human identity. If this is right then @schopenhauer1 is right to say that if my genotype were different then I would not be, could not be, the same organism, and therefore could not be the same person.

The usages of all of those are clear enough to know what we are talking about, no?

That is, sometimes you can switch out an A for a T or a G and have nothing happen other than this replacement, but the organism will continue to function even though the code is slightly different. — Moliere

Does this change the fact that each organism has a unique genotype?