[請益]進階三段邏輯題

看板logic作者 (哀便毛)時間16年前 (2009/04/07 20:18), 編輯推噓4(4推 0噓 18→)
留言22則, 4人參與, 最新討論串1/2 (看更多)
因不知如何search這題目是否在文章內文問過, 所以先問大家, ^^" 希望諸位高手指出我的盲點, Thanks! 前提: 1. Some Little Dog are not Mean Animals 2. All Dogs are Animals 結論: Some dogs are mean 請問這樣推論是否合理? 網路上正確解答是 "不合理" 理由是: Minimal missing premise: It exists something that is dog and mean or dog and not animal 但我想法比較單純, 我覺得是"合理"原因如下: 假設有以下幾類樣本, 讀法是 e.g. 1: Little + Dog + Not Mean + Animal 2: Little + Dog + Mean + Not Animal ... | L | D | M | A ------------------------ 1 | O | O | X | O 2 | O | O | O | X 3 | O | O | X | X 4 | O | O | O | O 前提2成立: 樣本2,3不存在 前提1成立: 樣本1,4同時存在, 因為只存在 樣本1的話, 前提應該是All Little Dog are not Mean Animal 樣本4的話, 前提應該是All Little Dog are Mean Animal 所以1,4同時存在, 表示Some Little Dog are Mean Animal->Some Dog are Mean 請指正, 謝謝 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 203.73.48.17 ※ 編輯: ntddt 來自: 203.73.48.17 (04/07 20:19) ※ 編輯: ntddt 來自: 203.73.48.17 (04/07 20:19)
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04/08 00:49, , 1F
考慮一種情形: all dogs are animals and not mean
04/08 00:49, 1F
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04/08 00:50, , 2F
符合前題(1)(2), 可看出結論錯誤
04/08 00:50, 2F
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04/08 01:34, , 3F
如果是All dogs are animal are not mean, 那條件some就有
04/08 01:34, 3F
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04/08 01:34, , 4F
問題, 應該是All little dog are not mean animal ?
04/08 01:34, 4F
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04/08 10:35, , 5F
這牽扯到some的定義,在英文中some可以是
04/08 10:35, 5F
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04/08 10:36, , 6F
more than one, possibly all
04/08 10:36, 6F
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04/08 10:36, , 7F
也可以是not all, possibly none
04/08 10:36, 7F
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04/08 10:37, , 8F
不過既然是邏輯,我想應該比較可能是particular quantifier
04/08 10:37, 8F
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04/08 10:41, , 9F
也就是existentail quantifier "∃"
04/08 10:41, 9F
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04/08 10:42, , 10F
也就是存在至少一個,可能全部的意思
04/08 10:42, 10F
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04/08 10:43, , 11F
抱歉上面more that one有點錯,應該是at least one
04/08 10:43, 11F
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04/08 13:26, , 12F
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04/08 13:26, 12F
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04/08 13:27, , 13F
查了字典, some有not all的意思的用法是 some of
04/08 13:27, 13F
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04/08 13:28, , 14F
If you refer to some of the people or things in a
04/08 13:28, 14F
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04/08 13:28, , 15F
group, you mean a few of them but not all of them.
04/08 13:28, 15F
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04/08 13:29, , 16F
If you refer to some of a particular thing, you mean
04/08 13:29, 16F
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04/08 13:29, , 17F
a part of it but not all of it.
04/08 13:29, 17F
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04/08 13:32, , 18F
...每次都從討論邏輯都變成討論語言...
04/08 13:32, 18F
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04/08 13:33, , 19F
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04/08 13:33, 19F
推
04/08 16:50, , 20F
印象中有些some of好像一定要用到second order才能表示
04/08 16:50, 20F
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04/08 19:50, , 21F
我猜邏輯上some應該是1~All, Only some才是1~(All-1), 那就
04/08 19:50, 21F
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04/08 19:51, , 22F
可以解釋這題目了. All A are B情況下, Some A are B成立
04/08 19:51, 22F
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文章代碼(AID): #19sqIaJ3 (logic)
‣ 更多 ntddt 的文章
文章代碼(AID): #19sqIaJ3 (logic)