送交者: morningstar 于 August 27, 2002 11:04:03:
回答: 同意你的结论， 不同意你的证据。 ：-） 由 日尧 于 August 27, 2002 10:18:57:
First a clarification. I don't think there is anything wrong with Russel's logic. I wasn't sure if your post is for me or for FZ.
The key to eliminate the confusion, I think, is to make clear whether the sentence is a definition or a statement.
For example, if I take
"直角三角形是一个三角之和等于180度的三角形"
as a definition of 直角三角形, then I can certainly deduce that all 三角之和等于180度的三角形 is 直角三角形 which certainly does not make sense. There is nothing wrong with the logic though. The problem is with the definition.
However, if we take the almost the same sentence "直角三角形的三角之和等于180度的三角形", which is a statement, then base on this we cannot say that all 三角之和等于180度的三角形 is 直角三角形. Note the change of the wording. To me, 直角三角形是一个三角之和等于180度的三角形 sounds more like a definition.
Logic usually is not the problem. It is the assumption or definition which tends to lead us astray. I have to admit though that most of the computer scientists are more thoroughly trained in logic than physicist.