Personal Identity Over Time - TCE Philosophy (Tasmania)
“Personal identity: bodily, psychological and no-self theories”
Personal identity asks what makes a person at one time the same person at a later time, despite all the changes they undergo. The bodily theory says it is bodily continuity. John Locke's psychological theory says it is continuity of memory and consciousness. Derek Parfit argues identity is not what matters and reduces to degrees of psychological connectedness. Buddhist philosophy denies there is any persisting self at all.
What this dot point is asking
This dot point belongs to the metaphysics strand of the TASC Philosophy course. You are asked to explain the main criteria of personal identity, test them with thought experiments, and assess which best survives the objections.
The problem
You change constantly: your cells replace themselves, your beliefs shift, your appearance ages. Yet we ordinarily assume the person reading this is the same person who was a child years ago. What grounds that sameness? A good theory of personal identity must explain why a single person persists through such change, and the answer matters for responsibility, survival and what we should care about.
Being one and the same individual, not merely being exactly similar. Two new tennis balls are qualitatively identical but numerically distinct. Personal identity over time is a question of numerical identity: are the earlier and later persons literally one and the same?
The bodily theory
The simplest view is that you are the same person because you have the same body, or more precisely the same living organism. This fits everyday practice, since we reidentify people by their bodies. But it faces problems. Thought experiments about brain transplants suggest that if your brain were moved to a new body, you would go with your brain, not stay with your old body. This pushes many toward locating identity in the brain or, more abstractly, in the mind the brain supports.
Locke's psychological theory
John Locke argued that personal identity consists in continuity of consciousness, especially memory. You are the same person as someone in the past if you can remember their experiences from the inside. This neatly explains why we hold people responsible only for what they did as the same conscious self. Thomas Reid objected with the brave officer paradox: a general remembers being a brave officer who remembers being a boy who stole apples, but the general does not remember the apple theft. By memory alone the general is and is not identical to the boy, which is contradictory. Later theorists repair this by appealing to overlapping chains of psychological connections rather than direct memory.
The psychological theory survives Reid's objection by switching from direct memory to psychological continuity: a connected chain of overlapping memories, intentions and personality, even where no single memory reaches all the way back.
Parfit and what matters
Derek Parfit used teleportation and fission cases to argue a radical conclusion. Imagine your brain is split and each half placed in a new body, yielding two people each psychologically continuous with you. They cannot both be you, since they are two and you are one, yet there is no reason to favour either. Parfit concludes that personal identity is not what fundamentally matters. What matters is psychological continuity and connectedness, which can hold to degrees and can branch. On this reductionist view, the question of whether a future person will literally be you can be empty.
Suppose a teleporter scans and destroys your body on Earth and builds an exact replica on Mars. Bodily theory says you died and a copy lives. Psychological theory says the replica is you, since memory and personality continue. Parfit says stop asking whether it is you and ask only whether what matters, psychological continuity, is preserved.
The no-self view
Buddhist philosophy, through the doctrine of anatta, denies there is any enduring self underlying experience. What we call a self is a bundle of constantly changing physical and mental processes, an idea strikingly echoed by David Hume, who reported that when he looked inward he found only particular perceptions and never a self. On this view the search for a criterion of identity rests on a mistake, since there is no single persisting thing to track.
Evaluating the theories
A strong answer recognises a trade-off. The bodily theory is concrete but yields the wrong verdict in brain-swap cases. The psychological theory matches our intuitions about responsibility but struggles with duplication. Parfit dissolves the puzzle but at the cost of denying that survival matters in the way we assume. For the exam, run a thought experiment, state what each theory predicts, and argue which result is least revisionary or most defensible.
Saying I am a completely different person now can mean either that you have changed a lot (qualitative) or that you are literally not the same individual (numerical). The philosophical question is about numerical identity. Do not slide between the two senses, since most change leaves numerical identity intact.
Exam-style questions
Questions in the style of TASC exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
Practice6 marksExplain Locke's psychological (memory) theory of personal identity and one objection to it.Show worked answer →
A 6 mark response needs Locke's view and a clear objection.
Locke's theory. Personal identity consists in continuity of consciousness, especially memory: you are the same person as someone in the past if you can remember their experiences from the inside. This explains why we hold people responsible only for what they did as the same conscious self.
Objection. Reid's brave officer paradox: a general remembers being a brave officer who remembers being a boy who stole apples, but the general does not remember the theft. By memory alone the general both is and is not identical to the boy, which is contradictory.
Markers reward an accurate statement of the memory criterion and a clearly explained objection. Strong answers note the standard repair: switch from direct memory to overlapping chains of psychological continuity.
Practice16 marks"Personal identity is not what matters in survival." Critically evaluate Parfit's claim, comparing it with the bodily and psychological theories.Show worked answer →
A 16 mark extended argument essay should set out the theories and assess Parfit's reductionism.
Exposition. Bodily theory: same person because same living organism/brain. Psychological theory (Locke, refined as continuity): same person through connected memories and personality. Parfit: using fission cases (your brain split into two psychologically continuous people, who cannot both be you), he argues identity is not what fundamentally matters; what matters is psychological continuity and connectedness, which can hold to degrees and can branch.
Case for Parfit. Fission shows identity can fail to have a determinate answer while what we care about (continuity) is preserved twice over, so identity is not the thing we should value.
Objections. The bodily and psychological theories better match ordinary intuitions about survival and responsibility; denying that identity matters is highly revisionary, and the teleporter and fission cases may be too fanciful to ground conclusions. The Buddhist no-self view and Hume's bundle theory support Parfit by denying a persisting self at all.
Judgement. Conclude with a defended position, for example that Parfit successfully separates identity from what matters but at a revisionary cost, so the claim is defensible but counterintuitive. Markers reward accurate theories, a correctly described fission case, and a reasoned conclusion.