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Single Idea 19192
[filed under theme 5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle
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Full Idea
With our definition of truth we can prove the laws of contradiction and excluded middle. These semantic laws should not be identified with the related logical laws, which belong to the sentential calculus, and do not involve 'true' at all.
Gist of Idea
The truth definition proves semantic contradiction and excluded middle laws (not the logic laws)
Source
Alfred Tarski (The Semantic Conception of Truth [1944], 12)
Book Ref
'Semantics and the Philosophy of Language', ed/tr. Linsky,Leonard [University of Illinois 1972], p.26
A Reaction
Very illuminating. I wish modern thinkers could be so clear about this matter. The logic contains 'P or not-P'. The semantics contains 'P is either true or false'. Critics say Tarski has presupposed 'classical' logic.
The
24 ideas
from 'The Semantic Conception of Truth'
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19179
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For a definition we need the words or concepts used, the rules, and the structure of the language
[Tarski]
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19178
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Definitions of truth should not introduce a new version of the concept, but capture the old one
[Tarski]
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19177
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A definition of truth should be materially adequate and formally correct
[Tarski]
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19180
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It is convenient to attach 'true' to sentences, and hence the language must be specified
[Tarski]
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19181
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In the classical concept of truth, 'snow is white' is true if snow is white
[Tarski]
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19182
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Use 'true' so that all T-sentences can be asserted, and the definition will then be 'adequate'
[Tarski]
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19183
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Each interpreted T-sentence is a partial definition of truth; the whole definition is their conjunction
[Tarski]
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10824
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If listing equivalences is a reduction of truth, witchcraft is just a list of witch-victim pairs
[Field,H on Tarski]
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19184
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The best truth definition involves other semantic notions, like satisfaction (relating terms and objects)
[Tarski]
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19185
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Semantics is a very modest discipline which solves no real problems
[Tarski]
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19186
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A rigorous definition of truth is only possible in an exactly specified language
[Tarski]
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19187
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The Liar makes us assert a false sentence, so it must be taken seriously
[Tarski]
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19188
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We can't use a semantically closed language, or ditch our logic, so a meta-language is needed
[Tarski]
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19189
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The metalanguage must contain the object language, logic, and defined semantics
[Tarski]
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19190
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We need an undefined term 'true' in the meta-language, specified by axioms
[Tarski]
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19191
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Specify satisfaction for simple sentences, then compounds; true sentences are satisfied by all objects
[Tarski]
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19192
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The truth definition proves semantic contradiction and excluded middle laws (not the logic laws)
[Tarski]
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19193
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Disputes that fail to use precise scientific terminology are all meaningless
[Tarski]
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19194
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We may eventually need to split the word 'true' into several less ambiguous terms
[Tarski]
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19196
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Scheme (T) is not a definition of truth
[Tarski]
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19195
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Truth tables give prior conditions for logic, but are outside the system, and not definitions
[Tarski]
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19197
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Truth can't be eliminated from universal claims, or from particular unspecified claims
[Tarski]
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19198
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We don't give conditions for asserting 'snow is white'; just that assertion implies 'snow is white' is true
[Tarski]
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19199
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Some say metaphysics is a highly generalised empirical study of objects
[Tarski]
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