In which of the following does the (a)-sentence NOT entail the (b)-sentence?
A(a) X is a cat. (b) X is an animal
B(a) X is a cat. (b) X is a quadruped
C(a) All dogs are purple. (b) My dog is purple
D(a) X is a cat. (b) X has four legs正確答案
答案與詳解
為什麼答案是 D
(a) 不蘊涵 (b)。有四條腿（has four legs）描述的是經驗世界中的具體物理狀態。一隻貓可能因意外而少於四條腿，此時X是貓為真，但X有四條腿為假，故不構成必然的蘊涵關係。
載入中…
