Personal Identity: The Question

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Theme

What is metaphysically necessary
for your survival?
chocolate

Note that our question is not equivalent to one about what it takes for you to continue as a new person.

‘I am a different person now’

The way this is put implies that you continue to exist; (it’s you, not someone else, who has become a different person).

[Olson’s formulation] If a person exists at one time and something exists at another time, under what possible circumstances is it the case that the person is the thing?

Ok, let’s illustrate the question with two examples

Omar suffers from a rare brain-destroying disease.

His sister Betty offers to donate her left brain hemisphere.

Omar’s brain is removed and Betty’s left hemisphere is implanted in his skull.

Does Omar continue to exist?

Theme

What is metaphysically necessary
for your survival?
chocolate

‘I am a different person now’

[Olson’s formulation] If a person exists at one time and something exists at another time, under what possible circumstances is it the case that the person is the thing?

Let me pause for a moment over the notion of identity ...

Key distinction: numerical vs qualitative identity.

numerical identity

This person has two ‘identities’, Superman and Clark Kent. In this sense, an ‘identity’ is something like a guise.

But numerically, there is only one person. (This is the point of the story, of course.)

Numerical identity is one of the simplest, clearest notions we have. Don’t complicated it by trying to be clever.

Siegel & Shuster, 1939 (Issue 1)

Numerical ‘Identity is utterly simple and unproblematic. Everything is identical to itself; nothing is ever identical to anything else except itself. There is never any problem about what makes something identical to itself; nothing can ever fail to be. And there is never any problem about what makes two things identical; two things never can be identical’ \citep[pp.~192--3]{Lewis:1986zq}.

‘Identity is utterly simple and unproblematic.

Everything is identical to itself; nothing is ever identical to anything else except itself.

There is never any problem about what makes something identical to itself; nothing can ever fail to be.

And there is never any problem about what makes two things identical; two things never can be identical.’

Lewis, 1989 pp. 192--3

Theme

What is metaphysically necessary
for your survival?
chocolate

‘I am a different person now’

[Olson’s formulation] If a person exists at one time and something exists at another time, under what possible circumstances is it the case that the person is the thing?

‘Few concepts have been the source of more misunderstanding than identity over time. The Persistence Question is often confused with other questions or stated in a tendentious way.’

Olson, 2019

\citep{olson:2019_personal}

Theme

What is metaphysically necessary
for your survival?
chocolate

‘I am a different person now’

[Olson’s formulation] If a person exists at one time and something exists at another time, under what possible circumstances is it the case that the person is the thing?

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Personal Identity: The Question

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