理則學練習07 範例 (取自梅子姐) - ஜ無限世界ஜ

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理則學練習07 範例 (取自梅子姐)

2007/12/07 18:33:11瀏覽531｜回應0｜推薦0

A-15. No motorcycles are limousines. All motorcycles are fast vehicles. So no fast vehicles are limousines.

以"M"表"中詞motorcycles "；"S"表"小詞fast vehicles "；"P"表"大詞limousines"

　　 No motorcycles are limousines

　　 All motorcycles are fast vehicles

∴　 No fast vehicles are limousines

左邊論證的邏輯形式如右：

　　No M are P

　　All M are S

∴　No S are P

由簡化的論證形式可知，此論證的

mood是EAE

figure是figure3

此論證無效。

B-6. All friends of mine are people on the team. Some friends of mine are people 7 feet tall. So some people 7 feet tall are people on the team.

以"M"表"中詞friends of mine "；"S"表"小詞 people 7 feet tall"；

"P"表"大詞people on the team"

　 All friends of mine are people on the team

　 Some friends of mine are people 7 feet tall

∴ Some people 7 feet tall are people on the team

左邊論證的邏輯形式如右：

　　All　M　are　P

　 Some M　are　S

∴ Some S　 are P

由簡化的論證形式可知，此論證的

mood是AII

figure是figure3

依照大、小兩前提可畫出此論證的范恩圖，可從左圖得知，S與P交集的部份有一定不是空集合的部份，因此可導出「有些S不是P」。所以這是有效論證。