(This is a long post which I have been unable to break up. Take it in stages.)
Philosophers since Plato have worried at what exactly Identity and Personal Identity are. They do this by logicking on the words (or ‘concepts’).
The literal meaning of ‘identity’ from its Greek origins is ‘sameness’ or ‘state of being the same’. But this is not enough for philosophers.
Identity, or what it is for a thing or person to be the same, has been a singular subject of philosophers’ concern since ancient times. It is a good example of their logicking through the ages (which gives no wisdom and no education, as someone who turned to me in a philosophy class once said).
On personal identity, moreover, they have actually worried at how they can know for sure they are the same persons they were in childhood. They take for granted they are, but how do they know for sure, how can they prove it? (from here)
Here we start on the philosophizing on Identity:
The philosophical meaning of Identity (or ‘being itself’) is the relation each thing bears only to itself (see here). I wouldn’t have dreamt of trying to logic even this far.
But philosphers go further: ‘Identity’ is the relation between entities x and y only if they are in fact the same thing, i.e. identical, i.e. x=y.
And further still: If x and y share exactly the same properties (or ‘predicates’), are they one and the same thing? Yes they are, according to the Principle of Indiscernibles (from here). This seems also to be known as the Law of Identity, originating from Plato and restated by Leibniz (from here).
And even further: How can a person at one time and at a later time be one and the same person? The first time I read this, I thought they must be joking, but no, philosophers do feel a need to justify by logicking that one remains the same person.
I see in passing that the post on this subject in Internet Encyclopedia of Philosophy goes even into formal logic for this subject, even into what looks like mathematics.
Here are other questions that philosophers have thought on:
What does it mean for an object to be the same as itself?
If x and y are identical, i.e. the same thing, must they always be identical? Are they necessarily identical?
If an object’s parts are entirely replaced over time, as with the Ship of Theseus rotting in harbour, in what way is it the same? This seems similar to the matter of human personal continuity.
Here are further individual words and statements that indicate the ways of mind of philosophers on this subject (from here):
Leibniz’s Law figured in his invention of calculus. Identity is sometimes distinguished from Equality. Identity in mathematics may be an equation that holds true for all values of a variable. Hegel argued that things are inherently self-contradictory, and that the notion of something being self-identical only made sense if it were not also not-identical or different from itself. Hegel wrote, “Identity is the identity of identity and non-identity.” Recent metaphysicians have discussed trans-world identity—that there can be the same object in different possible worlds. An alternative to it is in Counterpart theory.
(This kind of thinking is for me in a cold, dead universe of singing planets that I cannot float out into for fear of being dead.)
Some philosophers have denied there is such a ‘relation’ as identity. Wittgenstein, here: “That identity is not a relation between objects is obvious.” And: “Roughly speaking: to say of two things that they are identical is nonsense, and to say of one thing that it is identical with itself is to say nothing.” (That sounds to me surprisingly sane.)
Bertrand Russell had earlier written in The Principles of Mathematics §64: “Identity…cannot be anything….Two terms plainly are not identical, and one term cannot be, for what is it identical with?” Gottlob Frege had even earlier wondered whether Equality was a relation. Here are two further philosophers who seem to think that ‘identity’is nothing very much: C. J. F. Williams has suggested that identity should be viewed as a second-order relation rather than a relation between objects (but I don’t understand what ‘second-order’ means.) Kai Wehmeier has argued that thinking of a binary relation that every object bears to itself, and to no others, is logically unnecessary and metaphysically suspect! (from here). (The latter seems to be similar to Wittgenstein and Russell’s viewpoints.)
Philosophers differentiate between numerical and qualitative identity. (I have borrowed many of the words below from here).
If I say I drive the same car as Jane, it may mean that Jane and I drive one and the same car, which would be numerical identity, or it may mean that Jane and I drive the same make and model, which would be qualitative identity. Beers in a six-pack are numerically distinct but qualitatively identical.
If A and B are numerically identical, they are one and the same, not two separates. If A and B are qualitatively identical, they might be one and the same thing but they don’t have to be. ( My mind is already worn out by the uselessness and unprofundity of it all.)
Qualitative identity can then be separated into ‘loose’ and ‘strict’. ‘Loose’ means that two of the same hamburgers may differ slightly, in size for example. ‘Strict’ means complete sameness, i.e. indiscernibility.
Numerical and qualitative identity is relevant to Heraclitus’ s famous question: Can one step into the same river twice? i.e. is it the same river?
Philosopher Stephen Law thinks you can easily solve this puzzle with the insight that the river you’ve jumped into twice is obviously numerically the same thing, but qualitatively different in that qualities and exact constituents have changed over time.
Numerical identity means that the number of objects is only one. Qualitative identity means that two separate things share the same qualities (e.g. two billiard balls that are molecule-for molecule duplicates of each other).
This, they say, is an example of how philosophers, by unpacking and clarifying concepts, can solve a puzzle, in this case, Heraclitus’s ancient one.
But has ‘numerical’ and qualitative’ solved Heraclitus’s puzzle?
Law presupposes a distinction between individuals and qualities, that one and the same individual has different qualities at different times. Thus one and the same river is stepped into at different times.
But according to Heraclitus’s doctrine of flux, there are no individuals that remain self-same over time. There is no substrate underneath the change. Change cuts so deep that it cannot be confined only to the properties of a thing, with the thing itself as substrate staying unchanged. For Heracliteans as for Buddhists, it’s flux all the way down to the thing as numerical entity itself.
(I had always thought Heraclitus was saying that one can’t step into the same river twice because its constituents had changed; but now the writers of this post seem to say that H. thought it was still the same river that one was stepping into, because it itself in its numerical identity essentially consisted of change.)
H.’s doctrine of flux launches us into a labyrinth of ontological problems of ancient philosophy with no accepted solution (see next paragraph). A thing and its properties are now not distinct, and therefore nor is numerical and qualitative identity.
Here is some of the ancient, metaphysical, ontological labyrinth: Just what is a thing or ‘substance’ distinct from its properties? Is it Aristotle’s primary substance? What exactly is Aristotle’s prote ousia? Is a thing a bundle of its properties? And what is a property? An abstract object? In what sense of ‘abstract’? A universal? A trope? Are there are no properties at all, only predicates? And what about the thing’s having of properties? What is that? And so on, according to philosophers. (My mind has always been lost.)
But still, this post by a philosopher does say that the distinction between numerical and qualitative sameness does work at the level of ordinary language. To think clearly and avoid confusion, one must use it. Heraclitus’s theorizing was something else, something in ancient metaphysics. He was saying that one was stepping into the same river twice, not because it was numerically the same (though qualitatively different) but because each object is always changing its properties yet retaining its identity. (I’m not sure now whether I’ve got that exactly right but it doesn’t matter because its all wrong-headed.)
Philosophers theorize on Personal Identity, (from here).
In Sociological departments, ‘identity’ concerns one’s self-conception and social presentation; and the aspects of one that make one qualitatively different (such as cultural identity, gender identity, national identity.)
In Psychology, there is a slightly different definition of personal identity (see here,under ‘Psychological Continuity’). It consists, to my mind, of two amazing paragraphs.
But in Philosophy (from here), personal identity is the numerical identity of a person, which means that he is one and the same person! not two persons who share the same qualities! (from here.) “Personal Identity also comprises the necessary and sufficient conditions[!] under which a person at one time and a person at another time can be said to be the same person”(from here). It concerns such matters as what kind of thing a person is, and (to repeat) how does the same person continue from one time to the next.
Philosophers have different theories on how the same person retains his sameness over time – which seems to be no different than the problem: What is personal identity (from here).
In what follows, I will use ‘person’, ‘self’, ‘personal identity’, and even ‘persistence’ and ‘continuity’, as meaning the same thing.
As Locke seems to have written (from here): ‘PERSON….is the name for this self. Wherever a man finds what he calls himself, there, I think, another may say is the same person. It is a forensic term, appropriating actions and their merit; and so belong only to intelligent agents, capable of a law, and happiness, and misery.’ (So Locke is saying that ‘person’ means ‘self’, and possibly also that the Law sees actions as being the responsibility of this person).
One philosophical theory of how a person retains his sameness over time is that he has the same body! (from here). The trouble is that one’s body over the years does not consist of the same materials, and nor did the ancient Ship of Theseus example. So one has to modify the theory to say that it is the biological processes, rather than continuity of the same materials, that comprise continuity. It is a materialistic theory, that one’s self is a biological organism, with no mention of any mental factors continuing.
[Some philosophers have taken seriously the teletransportation which occurred in Star Trek (from here). Their question is: If a person is atomically deconstructed on Earth and re-assembled on Mars, where does the transmitted person stop being identical to the initial person on Earth? This question appears to show that having a numerically identical physical body is not the criterion for personal identity (in that I suppose the person had been physically deconstructed and put together again, and yet is the same person).]
Another theory is that continuity of personal identity is to have the same Mind or ‘Mental Substance’ (from here). This theory has its problems for philosophers in that many of them aren’t sure or don’t think that Mind is an immaterial substance! They can’t make logic out of the concept of stimulation of the sensory organs in our material body causing sensations in the immaterial mind! and in the reverse direction, how thoughts in the immaterial mind can cause muscles to contract as desired! (I’ve never been bothered with it. They just do. Logicking oneself to a standstill doesn’t help.)
This Mind-Body puzzle, dating from at least Descartes, gives philosophers difficulty with the theory that one’s Mind constitutes one’s Personal Identity over time, but I don’t for the moment understand how.
Locke’s theory was that personal identity is to have continuity of consciousness (from here.)
This appears in his An Essay Concerning Human Understanding (1690), (in Book II Chapter XXVII “On Identity and Diversity”). He also thought that consciousness was just memory. He conceived of “continued consciousness” as being distinct from the soul in that, for one thing, the soul may have no consciousness of itself, as in reincarnation. (That latter statement seems unargued. Is it from the New Testament?)
Anyway, according to Locke, one is the same person in that one is conscious of one’s past thoughts and actions.
Locke now connects this with Morality and Law: Because one’s self is one’s memory, other people can attribute moral responsibility as well as punishment and guilt to oneself.
How does Locke argue that? — by saying, it seems, that one’s self extends to its past only by its memory, and this makes it accountable for its past actions, just as for its present ones! (That doesn’t sound satisfactory to me.)
Locke seemed to say also that what one did was in pursuit of happiness which is the unavoidable concomitant of consciousness, which is the consciousness of pleasure and pain, desiring that that self that is conscious should be happy. (Rather wordy, but so far, so good.) And therefore whatever past actions it is not conscious of cannot be accounted to it!
According to here again, there is then the problem in the law-court that since personal identity is based on consciousness, and that only oneself is conscious of one’s consciousness, the law-court may never know if it really is judging the same person, or simply the same body. All it can know is what the body has done.
But no, according to here, there is these days an insanity defence in that we are only held responsible for acts we are conscious of!
Here are some further apparent problems for Locke’s theory:
If Personal Identity consists of the identity of consciousness, then if two people have exactly the same consciousness, the same memories, they must be the same person! (But does Locke think this happens in real life?)
Also: If one accepts that Socrates awake, and Socrates asleep and dreaming, do not have the same consciousness, then (according to Locke) they are not the same person! To punish Socrates awake for what dreaming Socrates was conscious of doing, would be like punishing one twin for what the other was doing just because their bodies looked alike(from here again).
Here is another problem, apparently raised by Locke himself: If one claims to be a reincarnation of Plato, one would really only be him if one had the same consciousness of past thoughts and actions (from here). (This seemed important to Locke, but why would anyone want to claim to be Plato, and who ever did so?)
Locke thought that even the personal identity of animals is not in their changing bodily substance but in their “identity of life”. (What is that latter? I need argument on the intuition that animals don’t have personal identity by way of continuity of consciousness.)
In this paragraph are three separate ideas (from here) that I don’t see the argument behind, although they bring a sense of profundity and ultimacy to the philosophers’ logicking on this subject: Firstly, Locke’s theory of self owes something apparently to the apocalyptic “great day” of Christianity when the coming of divine justice will make up for our miserable state on Earth and for the failings of human justice. Secondly, the problem of personal identity is at the center of discussions about life after death. Thirdly, in order to exist after death, there has to be a person after death who is the same person as the person who died.
A similarly ultimate statement comes here: “What does being the person that you are, from one day to the next, necessarily consist in? This is the question of personal identity, and it is literally a question of life and death, as the correct answer to it determines which types of changes a person can undergo without ceasing to exist. Personal identity theory is the philosophical confrontation with the most ultimate questions of our own existence: who are we, and is there a life after death? In distinguishing those changes in a person that constitute survival from those changes in a person that constitute death, a criterion of personal identity through time is given. Such a criterion specifies, insofar as that is possible, the necessary and sufficient conditions for the survival of persons.”
Philosophical intuition. This is the heading given here to philosopher Bernard Williams’s fictional situations or ‘thought experiments’. It seems that BW was only speculating on what ordinary people’s intuitions are, rather than offering a theory of his own.
In the first situation, two persons were told their minds would be swapped between their bodies, and asked to choose whether reward or punishment for what they had done before the swap should be given to their minds or to their bodies after the swap. The intuition is that they would choose their minds to receive the sentence, that it is the mind that constitutes the self. Something like that! In the second situation, a person was told he will have his mind erased and then be tortured. Does he need to be afraid of being tortured? BW’s intuition is that people will be afraid of being tortured, since it is the body that is one’s self despite not having the same mind.
So these two fictional imaginings are supposed to show what people’s intuitions generally are on whether body or mind constitutes our selves. BW’s own intuition was that the latter intuition for the body being ourselves was the stronger in humanity. (My mind laboured and conked-out in semi-disbelief of my understanding of how philosophers’ minds worked doing this, so I may have got these thought experiments and their meanings wrong.)
Another philosopher thought up a situation where X’s brain is transplanted into Y’s body. Then X’s body and Y’s brain are destroyed, and the remaining person is Z. My mind failed me here too. A comment by someone else was that X and Y didn’t in fact swap bodies, but that Y falsely believed himself to be X, and therefore that Z was identical with Y. My mind gave up entirely here too.
Identity continuum (from here). In this theory of self, there is no”permanent identity” but only “thoughts without a thinker” − “a consciousness shell with drifting emotions and thoughts but no essence”. This is similar to the Buddhist concept of Anatta − “a continuously evolving flow of awareness” in which “the self changes at every moment and has no permanent identity” − a “constant process of changing or becoming”, a “fluid ever-changing self”.
The Bundle theory of the self of David Hume (from here) seems to me to be like the Buddhist concept in the previous paragraph.
In A Treatise Of Human Nature (1739), he wrote that there is no distinction between the features of a person (which change over time) and the Self that is supposed to bear those features. He wrote that we “.. are nothing but a bundle… of different perceptions which succeed each other with an inconceivable rapidity and are in perpetual flux….”.
Further, he wrote that our ideas are constantly rolling, our senses continually changing their objects of perception, and therefore so does our imagination constantly change. We then mistakenly think there must be a bond underlying them.
Hume, like Buddha, “compares the soul to a commonwealth, which retains its identity not by virtue of an enduring core substance, but by being composed of different, related, yet constantly changing elements….Personal Identity then becomes a matter of characterizing the loose cohesion of one’s personal experience.” (That seems to mean that Hume defines ‘self’ in some way as encompassing this ”commonwealth” of flitting things in our minds.)
Hume seems to think that there is “causation, contiguity, and resemblances…among the perceptions”. (That there is some sort of bond between them?)
Hume’s critics however say that for the various states of mind to seem unified, there must be something which perceives this unity (and that this presumably is the self). ‘Hume solves this by considering substance as engendered by the togetherness of its properties.’ (All this seems to mean is that Hume thought that the changing properties themselves constituted a togetherness, and this togetherness was a substance in its own right. ‘Substance’ goes back, I think, to the metaphysics of Aristotle.)
In the end, it does look as if Hume’s position is that of Buddhism except that he sees some sort of togetherness in the fluidity of mental contents, and that this togetherness constitutes ‘self’.
The No-self theory (from here) is that the concept of ‘self’ is incompatible with that of ‘bundle’. And anyway that the concept of ‘bundle’ implies bodily or psychological relations that do not exist (because I presume that there is no relationship between the ever-changing materials or between the ever-changing ideas). So the self can’t be a bundle, and anyway there is no bundle and no self.
Philosopher James Giles says that Hume is actually a no-self theorist in that he asserted that personal identity is a fiction. The Buddhist view of personal identity can also be seen as no-self theory in that our thoughts, personalities and bodies are ever changing .
According to the no-self theorists, ‘the sense of self is an evolutionary artifact, which saves time in the circumstances it evolved for. But [it ]breaks down when considering [such things as] memory loss, split personality disorder, brain damage, brainwashing, and various thought experiments’. (This needs more detailing for me.)
The changes in one’s mentality are very interesting, something to be thought about: How have they come to pass? Aren’t they simply a discovering of one’s true self by processes of education and experience, a coming back to finally be what one truly is. Those thoughts on the subject of personal identity or self-hood occur to me.
As T.S. Eliot wrote:”We shall not cease from exploration, and the end of all our exploring will be to arrive where we started and know the place for the first time….”, which means that finally we return to be ourselves and to know ourselves and the people who first formed us.
(He also wrote; “Hoo ha ha, Hoo ha ha, Hoo, Hoo, Hoo, Knock Knock Knock….”, and like that in other long passages too.)
But philosophers have thought it worth arguing out by logic and by almost mathematics, whether one actually is oneself, whether one actually has a self, and whether one is or isn’t the same person one was!