Lecture 9 Personal Identity

Topics for this lecture: The body theory, which leads to The brain theory The soul theory The psychological theory, which leads to The memory theory, which leads to Shoemaker’s quasi-memory theory Let’s try division/fission

The Notion of PI The idea of personal identity over time. You were at last week’s lecture; you once were 5 years old. That is, there was some person that was you, back then. Some student will be whipped next week in thelecture. It will be you! A new set of emotions…. Distinguish criteria of identity (what it consists in ) from evidence of identity.

Basic 3 views on PI The body theory. This can become the brain theory, which is slightly more restrictive. The Soul view, or the ‘simple’ view. The psychological view.

The body theory One can survive transplants … knees… other body parts… But what about a brain transplant? Shoemaker’s ‘Brownson’ case. So… we arrive at the theory that you need your brain to survive.

The Brain Theory But… Bernard Williams’ Brain State Transfer Device’. If so, the brain is no different from a leg. So… the brain theory is problematic.

The Soul/Simple View Idea that PI is irreducible. But: The knowledge problem. (See Perry.) On this view we could never know abut PI, either in others or even in our own case. Maybe our souls are changing every 5 minutes…Maybe there are 100 souls in my body all thinking the same thoughts?!

A Methodological Consideration… Question of what is important in survival (Recall a similar question that Dennett asks about free will.) Why do we want to survive… the plane trip …? It seems… we care about, our thoughts, plans, character, … continuing… We want the stream of consciousness to flow on.

The physical (body & brain) and soul theories do not explain why we want to retain the same body or soul… except insofar as our psychological life goes on… is retained. We wouldn’t care about retaining the same body or soul if our psychological life did not flow on.

The Psychological Theory Hence the idea that PI consists in psychological continuity is attractive. For it answers the valuing/caring criterion… that it explains why we might care about or value PI in the way we do.

The Memory Theory One version of the Psychological Theory is : the Memory Theory. Chains of memory relations. The general can remember being a soldier who can remember stealing apples as a child. (Fancy diagram here.)

John Locke

Circularity objection (Bishop Butler of Durham!) Shoemaker’s quasi-memory reply. Quasi-memories caused in the right way … A quasi-memory is an apparent memory or a memory experience.

The Bishop

Sydney Shoemaker

So you can’t remember being Guy Fawkes… Mental connectness idea. Methuselah’s… long life. Over-lapping chains of mental connectedness.

But…. Possibility of psychological splitting… Tele-transporter case… usually the original is destroyed… would be like a 3D Xerox.. Of you.

What about split brain cases. (Not merely imaginable, some real cases.) Two hemispheres, each a centre of consciousness. Strokes may wipe half brain… half seems to suffice.

Compare bridges, cities… can divide. … But then is survival a matter of degree? Is it black and white? Do questions about PI have clear abswers one way or the other? Puzzle cases, like the ship of Theseus.

What matters… links of psychological continuity, we want our mental life to flow on… If A splits… into B and C... fission…. Both can claim to be the descendent of A. But it is not the case that B=C. So neither is = with A. (Identity is ‘transitive’.)

Fusion? Put two brain in one body and join them. Better than death? Again it looks like survival is a matter degree… But… that is not how it seems from the inside. So… it is rather perplexing. A tricky one!

Finally….. Next week…. I won’t be here. Peter Vickers will finish off the topic of Personal Identity. Have a good well-earned break after next week and Good luck with the rest of KR!