Split IdentityNovember 2010

Lance RipsNorthwestern University

From Plutarch’s Life of Theseus

From Hobbes’ De Corpore

One-Iceberg Condition (from Rips, Blok, & Newman, 2006)

Original iceberg (Sample 94)

Successor iceberg

How similar is the new iceberg to Sample 94?

OR

How likely is the new iceberg to be Sample 94?

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Identity

From Rips, Blok, & Newman, Tracing the Identity of Objects. Psychological Review (2006).

Dimensions of Successor Iceberg

Two-Iceberg Condition (from Rips, Blok, & Newman, 2006)

Original iceberg (Sample 94)

Successor icebergs

Which is the original iceberg (Sample 94)?

Only the eastern-mostOnly the western-mostBothNeither

West East

Sample 94

West East

= =

= ?

(West = Sample 94) and (Sample 94 = East) West = East

From Euclid’s Elements

Two Experiments on Response Options

Which is Sample 94?1) Only the eastern-most2) Only the western-most3) Both4) Neither

1) Only the eastern-most2) Only the western-most3) The eastern-most and, simultaneously, the western-most4) Neither

Versus

Which is Sample 94?1) Only the eastern-most2) Only the western-most3) Both4) Neither

1) Only the eastern-most2) Only the western-most3) Both4) Neither5) Either the eastern-most or the western-most, but one can’t tell which.

Versus

59% Both 51% Both

46% Both 45% Simultaneous

An Experiment on Noun versus Adjective Interpretations

Suppose that on April 12 a group of scientists are studying an iceberg named Gax. On April 13, this iceberg splits into two icebergs… On April 14, which of the icebergs (if either) is the original iceberg (Gax)?

Baseline Condition:

Suppose that on April 12 a group of scientists are studying an iceberg that they have christened with proper name “Gax.” On April 13, this iceberg splits into two icebergs…

 On April 14, which of the icebergs (if either) is the original iceberg (Gax)?

Proper-name Condition:

Suppose that on April 12 a group of scientists are studying an iceberg that they describe as gaxish. On April 13, this iceberg splits into two icebergs… 

On April 14, which of the icebergs (if either) is gaxish?

Adjective Condition:

Both Neither East West 0

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Which is gaxish?

Which is the original iceberg Gax?

Which is the original iceberg (with proper name) Gax?

On April 14, which of the icebergs (if either) is the original iceberg (Sample 94)? (Please circle ONE of the responses below.)

Only the eastern-most iceberg is the original.Only the western-most iceberg is the original.Both icebergs are the original.Neither iceberg is the original.

Baseline Condition:

On April 14, which of the icebergs, considered on its own, is entitled to be the original iceberg (Sample 94)? In answering this question, you should ask yourself whether each iceberg has the qualifications it needs to be the original, ignoring the existence of the other iceberg. That is, supposing the other iceberg did not exist, could the remaining iceberg be the original? (Please circle ONE of the responses below.)

Only the eastern-most iceberg could be the original.Only the western-most iceberg could be the original.Both icebergs could be the original.Neither iceberg could be the original.

Entitlement Condition:

On April 14, what relations hold between the original iceberg and the eastern-most and western-most icebergs? In asking whether one iceberg is the same iceberg as another, we mean is it the very same (or identical) iceberg. This is the sense in which a person is identical only to him- or herself and not to a twin or a clone. We are NOT simply asking whether one iceberg has the same properties (e.g., shape or weight) as the other. Please circle either “yes” or “no” for EACH of the following three questions:

(a) Is the eastern-most iceberg the same iceberg as the western-most iceberg? yes no (b) Is the eastern-most iceberg the same iceberg as the original iceberg (Sample 94)? yesno (c) Is the western-most iceberg the same iceberg as the original iceberg (Sample

94)? yes no

Identity Condition:

Both Neither East West 0

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Which is identical?

Which is entitled?

Which is the original?

On April 14, which of the icebergs (if either) is the original iceberg (Sample 94)? (Please circle ONE of the responses below.)

Only the eastern-most iceberg is the original.Only the western-most iceberg is the original.Both icebergs are the original.Neither iceberg is the original.

On April 14, what relations hold between the original iceberg and the eastern-most and western-most icebergs? In asking whether one iceberg is the same iceberg as another, we mean is it the very same (or identical) iceberg. This is the sense in which a person is identical only to him- or herself and not to a twin or a clone. We are NOT simply asking whether one iceberg has the same properties (e.g., shape or weight) as the other. Which of the icebergs (if either) is the original iceberg (Sample 94)? (Please circle ONE of the responses below.)

Only the eastern-most iceberg is the original.Only the western-most iceberg is the original.Both icebergs are the original.Neither iceberg is the original.

Please circle either “yes” or “no” for EACH of the following three questions. On April 14: (a) Is the eastern-most iceberg the western-most iceberg? yes no

(b) Is the eastern-most iceberg the original iceberg (Sample 94)? yes no(c) Is the western-most iceberg the original iceberg (Sample 94)? yes no

On April 14, what relations hold between the original iceberg and the eastern-most and western-most icebergs? In asking whether one iceberg is the same iceberg as another, we mean is it the very same (or identical) iceberg. This is the sense in which a person is identical only to him- or herself and not to a twin or a clone. We are NOT simply asking whether one iceberg has the same properties (e.g., shape or weight) as the other. Please circle either “yes” or “no” for EACH of the following three questions:

(a) Is the eastern-most iceberg the western-most iceberg? yes no(b) Is the eastern-most iceberg the original iceberg (Sample 94)? yes no(c) Is the western-most iceberg the original iceberg (Sample 94)? yes no

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Old format and new identity instructions

Old format and old instructions

New identity format and old instructions

New identity format and new identity instructions

Before Split After Split

Three icebergs: 63%

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24

East

West

Sample94

One iceberg:

East

West

Sample94

Two icebergs:

East

West

Sample94

Justifications from One- and Two-Iceberg Subjects

One Iceberg:Subject A: “…the icebergs are all the same and thus only one iceberg has existed.”

Two Icebergs:

Subject B: “…they are 2 separate entities included in one sample.”

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Old format and new identity instructions

Old format and old instructions

New identity format and old instructions

New identity format and new identity instructions

Thanks to:Marianne Abouyared

Rita Biagioli

Rachel Bhagwat

Annum Bhular

Serge Blok

Sanford Goldberg

Doug Medin

George Newman

Eryka Nosal

Samantha Thompson

Sirisha Yadlapati

Richard Yao