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stand for/Proxyy/Vouch for/Existence of/Chisholm/Simons: only mereologically constant objects can stand for others. - (s) It would be pointless, that what something is "different" would be). - sum/Simons: no mereological constancy there would be nothing to prevent sums to be variable. - ((s) "is a variable sum" would be pointless) - Total: has their parts necessarily. - Or any other sum, example Tib + Tail but not Tibbles. - Vs: sum of variable parts: E.g. tail may again consist of different atoms.
Parts Oxford New York 1987