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Multi-valued logic: a logic that assumes more than the two classical truth values true and false. There are trivalent logics with possibility or indeterminacy as a third value. For tetravalent logics there are e.g. ¼ or ¾ as additional values that introduce a gradation in the rating. In the case of infinite-valued logics, the truth values can be interpreted as probability values.

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Annotation: The above characterizations of concepts are neither definitions nor exhausting presentations of problems related to them. Instead, they are intended to give a short introduction to the contributions below. – Lexicon of Arguments.

Author Item Summary Meta data
I 195
Multi-valued Logic / Geach: There is often a truth value X, that both p and ~ p have - problem: Then also p.~ p has the value X: (simultaneous assertion of p and ~ p) correctly: "it is just as likely that it will rain tomorrow, as it is likely that will not rain tomorrow"- but "it’s raining" and "it is not raining" can not have the same truth value, because then "it’s raining and it’s not raining" also has the same truth value - because the latter must be f.

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Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution.
The note [Author1]Vs[Author2] or [Author]Vs[term] is an addition from the Dictionary of Arguments. If a German edition is specified, the page numbers refer to this edition.

Gea I
P.T. Geach
Logic Matters Oxford 1972

> Counter arguments against Geach

Ed. Martin Schulz, access date 2020-02-23