(intro music)
Hi! I'm Nina Strohminger.
I work at Yale University in the School of Management and
the department a cognitive science.
And I'm Shaun Nichols
I'm a professor of philosophy at the University of Arizona.
Imagine it's the not-distant future
and you're in a car crash.
Part of your brain is damaged in the crash,
and the doctors have to replace it with a microchip.
But the microchip is faulty, and it doesn't
completely restore every part of your mind.
One way it could malfunction is it could lead you to
no longer be able to identify objects.
This is called "visual object agnosia."
Another malfunction the microchip is capable of producing
is it removes all of your desires and interests:
music you like, your hobbies, your goals for the future.
The microchip can also lead to amnesia
for all your experiences prior to the crash.
Finally, the microchip could lead you to lose your moral compass,
your ability to know the difference between right and wrong.
For which of these injuries to your mind
would your identity be the most altered?
Philosophy has provided multiple conjectures
about the answer to this kind of question.
Some philosophers, like Bernard Williams, have suggested that biological continuity,
having the same organism, is the most important part of identity.
On this view, the aspect of the scenario that would alter your identity the most
is the addition of the microchip to your brain,
because that's changing the organismic properties.
So it's not the changes to the psychological function that
matter primarily in this case.
It's the changes to the biology that matter.
An alternative account is the collection of psychological traits,
like personality traits and preferences, that that's the basis for identity.
In particular, the mental features that most allow us to differentiate one
person from another seem that they'd be
likely candidates for being a critical part of personal identity.
If that view is correct, then losing one's distinctive desires in memory should
cause the greatest change to identity.
Memory has traditionally been seen as
playing an especially crucial role in personal identity.
John Locke illustrates this idea with a
thought experiment about a prince and a cobbler.
Imagine the mind of a prince, containing all the prince's past experiences
were to enter into, and replace, the Cobbler's memories and experiences.
This new individual, is he the prince or the cobbler?
Locke think the answer is really obvious: of course this is the prince!
It's just that, now, the prince is inhabiting the body the cobbler.
More recently, it's been suggested that
morality is the most important part of identity.
Cultural folklore provides indirect evidence in favor of this idea.
For instance, in Western religious traditions,
souls are seen not only as an entity that lends us our unique identity,
but as the source of our conscience and moral action.
However, the view that morality is key to identity has not traditionally been
given much attention in philosophical circles.
Despite the central position this question has
occupied in philosophical debates,
it's only been recently that philosophers began collecting data
to show how people actually conceive of personal identity.
Locke believed that memories were the most important part of identity,
but does this map onto the way people actually think about identity?
To find out, Shaun and I ran a study where
we presented subjects with the microchip thought experiment.
People in this study overwhelmingly report that loss of the moral faculty
leads to the greatest change in someone's identity.
The elimination of memories and desires
also leads to a substantial change in identity, subjects report,
just not as dramatic as one produced by a loss of moral capacities.
Basic psychological processes,
like object recognition, are not
particularly important to identity permanence.
And mere physical changes, such as
installing the microchip that perfectly preserves
mental function leads to the lowest degree of perceived identity change.
When people consider what makes someone who they are,
they place central importance on moral capacity.
and this runs counter to perhaps the best-known theory of personal identity,
Locke's memory criterion, according to which you're the same person
just in case you remember having the experience of some past person.
In other studies, we've found what people regard as most important about
identity isn't really distinctiveness.
It's the moral traits.
And the moral traits that people have can be commonplace, and yet more critical to
identity than traits that are more distinctive.
So for instance, many people are nice, but losing that common trait is regarded as
a much more dramatic insult to one's identity
than losing some highly unusual preference, like a penchant for,
I don't know, watermelon infused with beef juice.
This study also illustrates the power of empirical data to shed light on
age-old philosophical problems.
While data can't provide a definitive answer
to the metaphysical question of what ought identity to be,
it can tell us how we think about our identities in everyday life.
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