|Presuppositions: are silent assumptions, which are contained in utterances. These assumptions are suggested by the context or conventions. E.g. "All my children sleep" presupposes that I have children. (See A. von Stechow, "Schritte zur Satzsemantik", ww.sfs.uni-tuebingen.de/~astechow/Aufsaetze/Schritte.pdf (26.06.2006) p. 80).|
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Presupposition/(Law of the) Excluded Middle/Geach: alleged counter-example against the sentence of the excluded middle: For example, from something that is not an animal, one might assume that it is neither true nor false that it is hungry. - So the predicate "animal" is presupposed. - Geach: presupposition is quite different from entailment: if "hungry" entails "animal" then: "non-animal" entails "not-hungry". - Problem: from a thing "not animal" would at the same time be hungry/non-hungry.
Definition hungry/Terminology: true of all that is hungry.
Definition not-hungry/terminology: true of everything of which "not-hungry" is true and "animal" is not true. - ((s) So no object since they cannot be "not-hungry".) Geach: Eliminates categorical differences of "hungry" and "animal".
Logic Matters Oxford 1972