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stronger / weaker / Grice: one should only make a weaker assertion (E.g. "He s either here or there") if you have a good reason for this -> E.g. "I have five Dollars," gives rise to the presumption that he has only 5.
H. Paul Grice
Handlung, Kommunikation, Bedeutung, Hg. Georg Meggle Frankfurt/M. 1993