What Makes Me Me: Personal Identity and Continuity over Time

The article gives no final answer and does not promise to settle the argument. It separates two questions — what makes a person the same, and what lets a person feel the same — and tests the candidates: the body, memory, character, links with the past, the story. The upshot of the comparison, as the authors see it, is that no candidate survives every change on its own; recognising “this is still me” rests on several links at once, and a change in one of them does not necessarily cut the others. Whether an unchanging core lies beneath these links, Hume and the Gita answer incompatibly, and the article does not settle that dispute. This is the authors’ conclusion from comparing philosophical, religious and psychological sources, not a research finding.

They are two different questions, and their answers need not coincide. The first is metaphysical: what makes a person the same as the one they were twenty years ago; it is answered with arguments and thought experiments, as by Locke, for whom a person is a thinking intelligent being that can consider itself as the same thinking thing in different times and places (An Essay Concerning Human Understanding, Book II, ch. XXVII, § 11 in the Project Gutenberg numbering). The second is psychological: what allows us to live our past as our own; it is studied with surveys and experiments — for example, Hong, Sedikides and Wildschut (2022) measured global self-continuity by having people list important aspects of their identity and rate how far each one made them feel a link between their past, present and future. A study can show that a person feels the same, but it cannot prove that an unchanging essence lies beneath the feeling; and a philosophical criterion does not by itself describe how a person experiences their life.

Plutarch (Life of Theseus, ch. XXIII) relates that the Athenians preserved Theseus’s ship, constantly replacing decayed timbers with sound wood, so that the ship became an illustration to philosophers: some argued that it remained the same, others that it did not. Plutarch does not settle the dispute; he records it. On the article’s reading, the dispute shows two senses of “the same”: the same material, or the same form, the same purpose and an unbroken history of replacements. A person, however, is not a ship: a ship does not remember its voyages and does not answer for them, while a person remembers and answers, so for personal identity the dispute about the ship is only a beginning. The distinction between the two senses is the authors’ reading of the example, not Plutarch’s words.

Locke (An Essay Concerning Human Understanding, Book II, ch. XXVII, in the Project Gutenberg numbering) draws the line this way: to be the same man also takes a body that is replaced gradually rather than all at once (§ 10), and to be the same person takes a consciousness able to own past thoughts and actions (§ 11). His thought experiment of a prince’s soul passing into a cobbler’s body (§ 17) tests intuitions: as a person this is the prince, yet to all but himself he would still be the cobbler. In surveys by Fernandez-Duque and Schwartz (2016), US residents judged that the “central self” depends on the brain more than the peripheral self does. The thought experiment does not prove that such a transfer is possible, and the surveys are data about the beliefs of one country, gathered in online surveys, not an answer to the question of what a person is.

Not on its own. Locke’s memory criterion (§ 11 in the PG numbering): as far as consciousness can be extended backwards to any past action or thought, so far reaches the identity of that person; its strong side is that it explains why we count as ours the actions we remember. Its weak side: most of what we have lived through we do not remember. Hume (A Treatise of Human Nature, Book I, Part IV, Sect. VI) asks whether anyone could recall what they thought and did on 1 January 1715, 11 March 1719 or 3 August 1733, and whether they would claim that their present self is a different person from the self of that time; memory, for Hume, does not so much produce as discover personal identity, and we extend the chain of causes beyond memory. The article’s conclusion is smaller than Hume’s: memory is a way of discovering one’s continuity, but not its only ground; this is Hume’s philosophical argument, not a medical statement.

According to two clinical works, partly. Platel and colleagues (2021) ran musical reminiscence workshops with 20 patients with moderate to severe dementia due to Alzheimer’s disease and 20 healthy residents of the same nursing homes; in their conclusion the authors write that both tests (IMAGE and I-AM) showed the patients’ self-representations to be stable, but, contrary to their hypotheses, no significant enrichment of the sense of identity was found, possibly because the measures were not sensitive enough. A systematic review by Stramba-Badiale and colleagues (2025, 83 studies) describes a consistent deficit of autobiographical memory in Alzheimer’s disease and, at the same time, that patients in mild to moderate stages keep some ability to access self-defining memories and a preserved sense of self-continuity. On the article’s reading, the experience of self does not track the amount of remembered material one to one; Locke is not refuted by this. The small sample and short time frame in Platel and colleagues, and the clinical populations in both works, do not allow these findings to be carried over to healthy people, and they yield no medical advice.

The article does not settle this dispute. Hume (Treatise, Book I, Part IV, Sect. VI), looking into himself, always comes upon some particular perception and calls human beings a bundle or collection of different perceptions; identity, for Hume, is something we ascribe to them because the imagination links their ideas. In the Appendix to the Treatise Hume admits that he is involved in a labyrinth and finds no satisfying theory of what binds perceptions together. The Bhagavad Gita (ch. II, verses 12–13 and 16–17, in Edwin Arnold’s verse rendering) answers the opposite way: changes — infancy, youth and age — happen to a bearer that does not itself change; this is a religious teaching about an indestructible soul, given by Krishna to a warrior before battle, not a psychological theory of personality. These are incompatible positions, not two versions of one answer: the question of a core is closed neither by observation nor by appeal to the authority of a single tradition.

At the end of the second chapter of the Zhuangzi (tr. Herbert A. Giles), Zhuangzi dreams he is a butterfly and, on waking, does not know whether he was a man dreaming he was a butterfly or is now a butterfly dreaming he is a man; right afterwards the text adds that a man and a butterfly are nonetheless divided by a boundary. Unlike Hume, the text speaks not of a gap in experience or of forgetting: Zhuangzi remembers the dream, and the doubt concerns which of the two perspectives is the original one. On the authors’ reading, the parable does not erase the difference; it shows that the certainty “I am I” does not rest on uninterrupted experience alone. This is the authors’ interpretation, not a thesis of the text itself, and no conclusion is built on the word Giles uses for the transition.

In surveys by Fernandez-Duque and Schwartz (2016), 172 US residents judged the “central self” more brain-based, less subject to willful control, more revealing of moral character and more stable across time; in a second survey (210 participants, 18 traits), how central a trait was rated went together with how desirable, how brain-dependent and how stable over time it seemed, but not with how moral or how controllable it was. A systematic review by Haehner, Wright and Bleidorn (2024, 30 longitudinal studies) found that merely wanting to change seems only weakly linked to actual trait change, while dedicated interventions on average shifted traits in the desired direction, though not all of them did; the evidence is still limited. These are correlational data about the beliefs of residents of one country (MTurk), and it does not follow that a person really has a moral core; how far personality traits persist across decades the article does not claim.

Montaigne (Essays, Book III, ch. 2 “Of Repentance”, tr. Charles Cotton) describes himself as an object that cannot be held still and admits that he may peradventure contradict himself but never contradicts the truth; Paul (1 Corinthians 13:11) speaks of himself as a child and as a grown man with one “I” and describes the change as putting away childish things. What they share is one thing: the past is told in the first person, and the teller does not disown it; so to say “back then I thought differently” is, on the article’s reading, neither to lie about one’s former self nor to disown oneself. Montaigne builds no theory of personal identity, and in Paul it is an image of growing up within a chapter about love; the article ascribes no theory of identity to either.

Hong, Sedikides and Wildschut (2022), in five studies (254, 250, 250, 174 and 146 participants: three correlational — online samples in the United States and the United Kingdom, and students in Korea — and two experiments), examined how nostalgia relates to the sense of self-continuity. Nostalgia predicted the sense of continuity and, in the authors’ conclusion, caused it in the two experiments; in the first of them the difference from the control group did not reach the 0.05 significance level (p = 0.056). As the authors summarise, nostalgia is linked to the sense of continuity, or strengthens it, chiefly through narrative (Studies 2–5), to a lesser degree through associative links (Studies 2 and 3), and not through stability; at the same time, belief in a stable self was itself related to the sense of continuity. For the article the conclusion is modest: for these participants, the feeling “this is still me” was related not only to a conviction that nothing had changed but also to how far a person sees their life as a story. Continuity and its grounds were measured with single items, associative links showed up in the correlational data but not in the experiments, and the samples were online and student samples.

In the first study by Ying Yang and colleagues (2024; 370 participants from a Chinese online sample aged 18–35, mean age about 19.5, questionnaires), future self-continuity significantly negatively predicted the time discount rate: the closer people felt to their future selves, the less they discounted delayed money; the link appeared only among those whose self-concept was clear. In the second study (234 students), in the authors’ model the effect of continuity on choice was mediated by the readiness to consider future consequences (which was measured, not manipulated) and depended on self-concept clarity; that knowing clearly who one is makes it easier to picture one’s future self vividly is the authors’ interpretation, not a tested mechanism. The samples were young and Chinese, the decisions were only about money, and the first study was correlational: it does not follow that feeling connected to the future is enough to manage one’s money or life wisely.

The article offers no method for “finding yourself”; a few cautious steps follow from it, and each works only within its limits. When you feel like saying “I am not the same person anymore,” it helps to specify which link has changed: the body, memory, character, relationships or the story you tell about yourself. You might try to put into words how earlier events led to present ones; this step itself was not tested in the study by Hong and colleagues, and the result is not guaranteed. Before a decision that concerns the future you can picture yourself a few years on as a continuation of who you are now; in an experiment with Chinese students a similar task was related to money choices, and this does not carry over automatically to other decisions. If someone close to you has dementia, it may help to know that studies describe preserved components of self-representation; decisions about care and treatment are made together with doctors. If memory lapses, a sense of unreality about yourself or abrupt changes of character persist, frighten you or get in the way of life, that is a reason to see a doctor. The article does not diagnose and gives no medical advice.