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Single Idea 16477
[filed under theme 3. Truth / A. Truth Problems / 7. Falsehood
]
Full Idea
When you do what a logician would call 'asserting not-p', you are saying 'p is false'.
Gist of Idea
Asserting not-p is saying p is false
Source
Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5)
Book Ref
Russell,Bertrand: 'An Inquiry into Meaning and Truth' [Penguin 1967], p.77
A Reaction
This is presumably classical logic. If we could label p as 'undetermined' (a third truth value), then 'not-p' might equally mean 'undetermined'.
The
15 ideas
from 'An Inquiry into Meaning and Truth'
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16477
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Asserting not-p is saying p is false
[Russell]
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16484
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There are four experiences that lead us to talk of 'some' things
[Russell]
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16486
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The physical world doesn't need logic, but the mental world does
[Russell]
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16483
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Disjunction may also arise in practice if there is imperfect memory.
[Russell]
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16480
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A disjunction expresses indecision
[Russell]
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16479
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'Or' expresses hesitation, in a dog at a crossroads, or birds risking grabbing crumbs
[Russell]
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16481
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'Or' expresses a mental state, not something about the world
[Russell]
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16487
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Maybe the 'or' used to describe mental states is not the 'or' of logic
[Russell]
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16475
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A 'heterological' predicate can't be predicated of itself; so is 'heterological' heterological? Yes=no!
[Russell]
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16482
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All our knowledge (if verbal) is general, because all sentences contain general words
[Russell]
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16476
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For simple words, a single experience can show that they are true
[Russell]
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16485
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Perception can't prove universal generalisations, so abandon them, or abandon empiricism?
[Russell]
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16478
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A mother cat is paralysed if equidistant between two needy kittens
[Russell]
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2947
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Questions wouldn't lead anywhere without the law of excluded middle
[Russell]
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4758
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Naïve realism leads to physics, but physics then shows that naïve realism is false
[Russell]
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