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