Using Neuroscience to Inform Theories of Personal Identity
Ben Dichter
“That’s Me”(I am the very same person as the person in that picture)
Ben Dichter, age 3 A lot has changed
• Physical Appearance
– Size
– Hair color
– Atoms in body
• Memory
– Gained memories
– Lost memories
Objectives
1. Philosophy of Personal Identity
2. Special Cases
3. Revisit the philosophy
Big Questions in Personal Identity
• Population: What makes two people distinct from each other?
• Persistence: Under what circumstances is a person existing at one time identical to a person existing at another time?
Persistence of cars
Modification
Gradually changing mostly same stuff same car
Modification
Mostly same stuff same car
Starting Point
Same stuff same car
Numerical Identity
• Space-time worm
– Really space-time rope
• Looking for metaphysical glue that makes two stages the same worm
Concept of Sameness
Same = similar Same = “the very same”
http://www.hoax-slayer.com/images/lead-lipstick.jpg
http://www.persuasiveconcepts.com/wp-content/uploads/2011/03/rose.jpg
http://cache.jalopnik.com/assets/resources/2008/04/Beetle_Before_After_494.jpg
Personal Identity
PopulationHow should we distinguish between two different space-time worms?
PersistenceHow should we connect two stages of a single worm?
Personal Identity
3 main approaches
– Soul (Dualism)
– Body
– Mind
Personal Identity
• A nonphysical substance
• Relation to physical world?
• Epiphenomenalism– Cannot be studied
– Basically have to make stuff up
• Plato’s soul swap
3 main approaches
– Soul (Dualism)
– Body
– Mind
Descartes
Personal Identity
• 3 main approaches
– Soul
– Body
– Mind
• Just like the car– Cells in my body change
like car parts
I am the same person if my matter undergoes only slow, gradual change.
Evil Mad Scientist’s Lab
I am the same person if my matter undergoes only slow, gradual change.
BRAIN
James Simkins Some other guy
The Mind Approach
• 3 main approaches– Soul
– Body
– Mind
• Locke: I am the same person if and only if I can remember being that person
• Problem:
A=B
B=C
A≠C
• Solution: rope again
Exploring the Mind Approach
• Someone wakes up and has the mind of Michael Jackson
– Remembers everything
– Same goals, fears etc.
• Is he Michael Jackson?
• Through the Mind Approach, yes
http://www.solarnavigator.net/music/music_images/michael_jackson_king_of_pop.jpg
Now we are stuck
• James wakes up as Oprah
• Problem: Oprah already exists
• We can fix this
– “No branching” rule
– Multiple occupancy
http://img.timeinc.net/time/daily/2006/0605/oprah0508.jpg
“Let’s give up”
• Anticriterialism: Personal Identity cannot be known
• “Open Concept”
– Is an escalator a staircase?
– No right answer
http://www.khanya.co.za/blogs/images/head_in_sand_2.gif
Objectives
1. Philosophy of Personal Identity
2. Special Cases
3. Revisit the philosophy
1. Tatiana and Krista Hogan
• Conjoined twins
• Neural bridge between thalami
– Receives sensory input from body
NY Times video
Youtube
http://a.abcnews.com/images/Nightline/ht_twinswhoshareabrain_08_100611_ssh.jpg
2. H.M.
• Epilepsy treatment: bilateral medial temporal lobectomy– Took out most of
hippocampus and rhinalcortex
• Full anterograde amnesia: cannot form long-term explicit memories
http://www.impawards.com/2001/posters/memento.jpg
Applying the Mind Approach to H.M.
Body Approach Mind Approach
Does H.M. die every time he spaces out?
3. K.C.
• Injured Hippocampus in motorcycle accident
• Good semantic memory, but no episodic memory
Semantic:
Who is president?
Where were you born?
• Cannot imagine himself in the future either
Does K.C. even have an identity rope?
Episodic:
http://flowtv.org/wp-content/uploads/2009/03/play-on-the-beach-350x233.png
4. Dissociative-Identity Disorder
• 2 personalities, Even and Odd
• Like housemates that never see each other
• Separation of identity appeals to both consciousness and memory mind approaches
4. Dissociative-Identity Disorder
Body Approach Mind Approach
Can a person go in and out of existence?
Objectives
1. Philosophy of Personal Identity
2. Special Cases
3. Revisit the philosophy
Why does it matter?
• Changed inmate
• Alzheimer's
• Neural prosthetics
• Robots
Philosophy is our umbrella
http://www.fatwallet.com/static/attachments/10312_maricopa_county_jail_inmate.jpg
http://media.mercola.com/imageserver/public/2008/April/4.1alzheimers.jpghttp://www.dianefenster.com/
brain_implant3.jpghttp://blackandteal.com/files/2010/08/irobot_1280.jpg
http://i691.photobucket.com/albums/vv271/IBleed4Thee/Grahpics/rainy_day.jpg?t=1242143276
Thanks!
Dr. Peter Machamer
UHC
Shelly Kagan
Aaron Batista
My dad
Questions?
5. Split-Brain
• Cut the corpus callosum to treat severe epilepsy
• If image is shown to left visual field, patient cannot verbally identify image
• Can react to image in other ways (laugh, grab object)
• 2 selves?
It’s a Cartesian trap!
• Temptation: 2 different selves
• Really just 2 different subsystems (homunculi)
• We have created a particularly obvious communication gap
• Communication gaps exist in all of us (e.g. body language)
Breaking Down the Cartesian Theater of Consciousness
Descartes:
• Consciousness cannot be subdivided
• We have privileged and infallible window into our own consciousness
• Homunculus within the brain
What we can learn
• We are color-blind in our peripheral vision
• Introspection does not always work
• If we are not looking, we will not notice it’s not there
• When in doubt, we make stuff up!
Our intuitions about consciousness may merely be the result of an illusion sustained by a combination of not looking and making stuff up.
Demonstration
2 volunteers please