1. What is the circularity objection to Locke’s theory of personal identity over time (either L1 or L2)?
Locke’s theory of personal identity states that a person P ex1sting at time t and1a person P exist2ng a later time
t are the same person (i.e. numerically identical persons) if and only if P and P have the same consciousness.
2 1 2
By this Locke means that a P1 is similar to P2 at a later time if P2 remembers the same events as P1. The
circularity objection proposed by Reid and Butler states that Locke’s view that personal identity is constituted by
memory is viciously circular since they do not think that memory constitutes personal identity but rather that it is
evidence of it. It is important to note that Locke analyzes personal identity in terms of first personal memories
(i.e. my memory of going to Paris last month vs. my memory of someone else going to Paris last month). A
correct first personal memory is a memory to the effect that I did or thought or felt something, which means that
the memory criterion presupposes personal identity. One must already have the concept of personal identity in
order to have the concept of (first personal) memory. This means that personal identity cannot be analyzed in
terms of memory and which is why Reid and Butler believe that Locke’s theory of personal identity is viciously
2. What, according to Nagel, are the five possibilities compatible with the brain bisection data? What
does Nagel think is wrong with each of these possibilities?
There are two cerebral hemispheres connected by the corpus callosum, which serves as an information conduit
between the hemispheres and each hemisphere’s connection to the body is different from the other. The
experiments: The split brain experiments concern patients who have had the corpus callosum severed, thus
preventing information flow between the two hemispheres. In everyday life, these patients seem just like normal
subjects. But in experimental situations set up to isolate their two hemispheres and the information each
controls, researchers observe extraordinary behavior. Many of the researchers carrying out the experiment take
the data to show that these patients have two independent “streams of consciousness.” Nagel says that five
possibilities are compatible with the data. They are:
(1) The patients have a mind associated with the left hemisphere and neither a mind nor any mental activity
associated with the (nonverbal) right hemisphere.
(2) The patients have a mind associated with the left hemisphere. Associated with the (nonverbal) right
hemisphere are episodes of mental activity not associated with any distinct mind.
Against (1) and (2): Suppose the left hemisphere failed. We would have no difficulty ascribing both a
(nonverbal) mind and (nonverbal) mental activity to the right hemisphere’s activities.
(3) The patients have two minds, one associated with the left hemisphere (which can speak and write) and
another associated with the right hemisphere (which can neither speak nor write).
Against (3): How can there be two minds when the two hemispheres are so well integrated in everyday
(4) The patients have a single mind whose contents derive from both hemispheres in a disassociated way.
Against (4): It is extremely difficult to conceive of what it is like to be a being with such a disassociated
(5) The patients have a single normal mind outside of experimental contexts, which splits into two minds as per
option (3) in experimental settings.
Against (5): Surely for such a drastic change to occur, the experimental set-up would have to bring about
some sort of internal change in the patients. It doesn’t.
3. Explain the duplication problem as it arises for the psychological continuity theory of personal
identity. What are some possible responses to the problem? What are some difficulties for these
The Psychological continuity theory of personal identity states that a person P exi1ting at time t and 1 person P 2
existing at a later time t are the same person (i.e. numerically identical persons) if and only P is the last link in a
chain of persons beginning with P where 1ach person in the chain is such that enough of his or her
psychological states (including “quasi-” states like quasi-memories) was caused by (at least some of) the
psychological states of the preceding person in the chain. Therefore, the psychological continuity theory locates
personal identity in the existence of chains of psychological continuity. Parfit discusses duplication cases that arise for the psychological continuity theory which ask what if there is more than one future set of mental states
psychologically continuous with yours? The duplication problem cases include multiple brain scan, brain
bisection and teletransportation. A teletransportation case works as follows: a person enters the machine and it
scans their body, recording all of their body and brain’s information. Their body is then destroyed. But in an
instance their body and brain’s information is radioed to another location, where local matter is combined in
accordance with the information. The result is a fully functioning human body just like the one that entered the
machine and has the same beliefs, desires, characters traits, and memories/ quasi memories as the prior person.
Psychological continuity is preserved. One day, you step into the machine, intending to beam down to the alien
planet’s surface. As a result of a malfunction, two copies of your body are created down on the planet, both of
which are associated with persons who appear to be psychologically continuous with you. There are six possible
options to determine which person are you:
(1) You are B but not C. Problem: arbitrary!
(2) You are C but not B. Problem: arbitrary!
(3) You are B and you are C. Problem: violates the transitivity of identity!
(4) You are neither B nor C; you have ceased to exist. Problem: Parfit: “How could a double success be a
(5) B and C form a “composite person” P and you are P. Problem: Weird!
(6) There was never only one you to begin with; there were two people, sharing your brain, body, and course of
experience all along, and the operation simply separated them. Problem: There didn’t seem to be more than
one person where you were at t 2
4. What is the difference between substance dualism and property dualism? Explain Princess
Elizabeth’s objection to Descartes’s interactionist substance dualism.
According to Descartes, there are two fundamentally different kinds of substances in the world: material
substances (material things are essentially extended and non thinking) and mental substances (souls or spirits are
essentially thinking and non extended). Descartes’ view was that extension is the hallmark of the material and