The Problem of Personal Identity Minds and Machines

Identity In general, what makes us ‘identify’ something as ‘something’ – Objects in Tarski world: cubes can be moved independently of each other -> each is their own thing Cubes are moved as a whole (not, e.g. as two half cubes … or ‘hubes’) -> the whole thing is ‘a thing’; one thing – Body parts

Qualitative vs ‘True’ identity Again Tarski’s world: – Objects: 2 Small Cubes – One cube has labels a and b – Other has label c Medium Cube: d Large Cube: e Large Tet: f Also: – Qualitative identity: concepts – True identity: instances

Persistence of (true) identity through time

Splitting and Combining

Disassembly E.g. computer

Copies If we make a perfect replication (physical and/or non-physical) of person A, do we have two persons A?

Splits What if a person A divides into 2 perfect replica’s of itself, the way cells divide into two?

Mergers What if two people merge into 1? Tuvix!

Ship of Theseus

Locke’s Principles

Personal Identity We all believe we are a unique person ‘I’ am ‘I’! But who or what is ‘I’?

Body View The ‘I’ is my body I am 5’11’’ tall. I weigh 150 lbs. I can run a mile in 6 minutes. Etc.

Mind View The ‘I’ is my mind I believe that philosophy is cool. I prefer strawberry ice cream over chocolate ice cream. Etc.

Identifying and Differentiating People Body view: – My body is how people identify me – One body -> one person – Two different bodies: two different persons Mind view: – Suppose you had some serious cosmetic surgery … or were in a serious accident. … Body View: – Suppose you have some serious brain injury because of the accident … or suffer from Alzheimer’s … or split personality disorder…

Brain Swaps Suppose we swap the brains of persons A and B: C has the body of A, and the brain of B D has the body of B, and the brain of A (assume the mind goes where the brain goes … both materialists and interactionist dualists can live with this) C is: – A – B – Both – Neither

Identity through Time Fortunately, the ‘I’ seems to be pretty ‘stable’, e.g. there does not seem to be an analogue to the chalk-splitting scaenario If I am my body (mind), would any change to my body (mind) mean that I no longer exist? No, because those are mere qualitative changes … as long as it is quantitatively the same body (mind), then you are still (quantitatively) the same person. OK, so some change is ok … but what about more radical change? What is the ‘end’ of ‘you’?