The Problem of Personal Identity
Change & Identity: A Quick Review
Two views about change and sameness (“Identity”):
1. Change requires that something become different than it was; but difference is the
opposite of sameness; so nothing can change and still be the same.
- Nothing stays the same [Materialism – Heraclitus] -> Atomism (Democritus)
- Nothing changes [Idealism – Parmenides] -> Plato
2. Things can undergo some changes …
Plato on Body and Soul (p.34)
“The soul is the very likeness of the divine, and immortal, and intellectual, and uniform, and
indissoluble, and unchangeable…
… and the body is the very likeness of the human, and mortal, and unintellectual, and multiform,
and dissoluble, and changeable.”
- old man, same as an infant
- every bit of him is different, and every day he is becoming a new man
- and not only his body, for the same thing happens to his soul, desire, pleasures,
sufferings, fears same throughout his life
The problem of personal identity
Given the many changes we undergo during our lives, what makes each of us numerically the
same persons for the duration of our lives?
1. Bodily Changes
2. Psychological Changes
1. Qualitative Sameness / Identity
2. Numerical Sameness / Identity
John Locke on Personal Identity (1689)
- Persons vs. Human Beings
- Identity is Relative (to classification)
- Memory criterion for personal identity
“Man” [Human being] vs. Person 1. Human Being: “… is nothing else but an animal of such a certain form” (38)
a) “Whoever should see a creature of his own shape or make, though it had no more
reason all its life than a cat or a parrot, would still call him a man [human] … a dull
irrational man.” (38)
b) “Whoever should hear a cat or a parrot discourse, reason, and philosophize, would
call or think it nothing but a cat or parrot … very intelligent rational parrot.” (38)
2. Person: “… is a thinking intelligent being, that has reason and reflection, and can
consider itself as itself” (39)
c) “Consciousness always accompanies thinking, and it is that which makes everyone to
be what he calls self” (39)
Consciousness and Self
- Consciousness: This is Locke’s term for our awareness of our own thoughts and
- All persons think and perceive, but we are, in addition, conscious of that fact about
- Self: ‘it is by this consciousness everyone is to himself that which he calls self’, and
‘consciousness … is that which makes everyone to be what he calls self’.
‘Of identity and diversity’
- Identity – one and only one thing can exist in a particular place at a particular time.
- Diversity – each thing is distinct from all others by virtue of occupying a particular
place at a particular time.
Identity is relative:
“The idea of identity [is] suited to the idea it is applied to” (38)
“We must consider the idea … it (identity) is applied to … it being one thing to be the same
substance, another to be the same man, and a third the same person.” (38)
Is X the same as Y?
Locke: The question is incomplete, and cannot be answered until we first clarify what we are
asking: Is it the same…WHAT?
Is X the same parcel of matter as Y?
Is X the same human being as Y?
Is X the same person as Y?
Is X the same ____ as Y? Rapid and Dramatic Change
- After Gregor’s transformation, the result is not the same man, nor the same human
- And yet, it was Gregor who awoke: “he found himself transformed”.
- How can it be Gregor? How can it be the same person?
John Locke on Personal Identity
“… It is the same self now as it was then.” (39)
- Even total (and rapid) bodily changes are possible while remaining the same person: