Consciousness and Personal Identitypersonal identity does not consist in sameness of body. But that’s not yet to say that Locke’s view
has been established, for we might think that there is another possible view consistent with the
body swap and consciousness transfer scenarios. Perhaps what’s important for personal identity is
not sameness of consciousness, but sameness of immaterial substance, i.e., sameness of soul (see,
e.g., Swinburne 1973–4 and Madell 1981). This kind of view about the nature of personal iden-
tity is often associated with dualist views about the nature of mind (see Robinson, Chapter 4,
this volume). In the contemporary literature about personal identity, it is often referred to as the
simple view.
In defending against the simple view, Locke asks us to consider a different kind of case.
Consider Thersites, a figure from Greek mythology who was supposedly present at the siege of
Troy. Now suppose that souls exist, and that someone existing today – call him Sunil – happens
to have Thersites’ soul. Is that alone enough to make Sunil the same person as Thersites? Locke
suggests that such a supposition would be absurd. For example, as depicted by Homer in the
Iliad, Thersites was struck across the back and shoulders by Odysseus in response to his having
sharply criticized Agamemnon; after being hit, he sat cowering, crying, and in pain. But presum-
ably Sunil can’t extend his consciousness backward to that experience no matter how he tries.
On Locke’s view, merely having the same soul as Thersites is as incidental to Sunil’s personal
identity as if Sunil’s body happened to be made up of some of the same particles of matter that
once constituted Thersites’ body. As he argues, “the same immaterial Substance, without the
same consciousness, no more [makes] the same Person, by being united to any Body, than the
same particle of matter, without consciousness united to any Body, makes the same Person”
(Locke 1689/1975: 339–340).
As these considerations suggest, there is something eminently plausible about a theory that
explains personal identity in terms of episodic memory. But that said, Locke’s own specifica-
tion of the view is threatened by several counterexamples. Recall that Locke requires that for a
presently existing individual to be the same person as some past existing individual, the present
individual must be able to extend her consciousness backward to the experiences of that past
individual. Since persons are prone to forgetting all sorts of experiences they’ve once had, this
requirement runs into serious trouble. Writing in the late 18th century, Thomas Reid force-
fully spelled out the problem with what’s become known as the Brave Officer case (Reid 1785).
Consider a brave officer, who while on a military campaign, engages in a heroic act. As a young
boy, this same man had stolen some apples from a neighbor’s orchard. And now, as a retired old
man, he has become senile. Though he still remembers his military career, including his act of
heroism, he no longer remembers stealing the apples. But assuming that while he was in the
military he still could remember this childhood theft, we’re presented with a paradox. Since the
retired old man can extend his consciousness backward to recall the experiences of the brave
officer, they are the same person. Since the brave officer can extend his consciousness backward
to the young thieving boy, they too are the same person. According to the principle of the tran-
sitivity of identity, if a is identical to b, and b is identical to c, then a is identical to c. So it seems
to follow that the retired old man is identical to the young thieving boy. But since the retired
old man cannot extend his consciousness backward to recall the experiences of the young thiev-
ing boy, Locke’s theory would deny that the retired old man is identical to the young thief. The
theory thus seems to lead to a contradiction.
2 The Continuity of Consciousness ViewIn response to this kind of worry, philosophers sympathetic with the spirit of Locke’s view
tend to suggest a modification of it. Rather than requiring that there be direct connections