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Single Idea 3110
[filed under theme 18. Thought / C. Content / 5. Twin Earth
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Full Idea
Humans are largely made of H2O, so there could be no twin on Twin Earth, and (as Kuhn noted) nothing with a significantly different structure from H2O could be macroscopically very like water (but topaz and citrine will do).
Gist of Idea
Humans are made of H2O, so 'twins' aren't actually feasible
Source
Gabriel M.A. Segal (A Slim Book about Narrow Content [2000], 2.1)
Book Ref
Segal,Gabriel M.A.: 'A Slim Book about Narrow Content' [MIT 2000], p.24
A Reaction
A small point, but one that appeals to essentialists like me (see under Natural Theory/Laws of Nature). We can't learn much metaphysics from impossible examples.
The
18 ideas
from 'A Slim Book about Narrow Content'
3104
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Must we relate to some diamonds to understand them?
[Segal]
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3103
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Maybe content involves relations to a language community
[Segal]
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3105
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Is 'Hesperus = Phosphorus' metaphysically necessary, but not logically or epistemologically necessary?
[Segal]
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3106
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If claims of metaphysical necessity are based on conceivability, we should be cautious
[Segal]
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3108
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If 'water' has narrow content, it refers to both H2O and XYZ
[Segal]
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3110
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Humans are made of H2O, so 'twins' aren't actually feasible
[Segal]
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3109
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If content is external, so are beliefs and desires
[Segal]
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3111
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Externalism can't explain concepts that have no reference
[Segal]
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3113
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The success and virtue of an explanation do not guarantee its truth
[Segal]
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3112
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Folk psychology is ridiculously dualist in its assumptions
[Segal]
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3116
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Maybe experts fix content, not ordinary users
[Segal]
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3117
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Concepts can survive a big change in extension
[Segal]
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3118
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If thoughts ARE causal, we can't explain how they cause things
[Segal]
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3119
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Even 'mass' cannot be defined in causal terms
[Segal]
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3121
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If content is narrow, my perfect twin shares my concepts
[Segal]
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3123
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Science is in the business of carving nature at the joints
[Segal]
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3124
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Externalists can't assume old words refer to modern natural kinds
[Segal]
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3125
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Psychology studies the way rationality links desires and beliefs to causality
[Segal]
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