老美的逻辑方式

再看stephen guide, 其中有一条不太理解,大家讨论下吧,我觉得有利于我们理解美国人的思维方式

7. Existential Fallacy

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Definition:
A standard form categorical syllogism with two universalpremises has a particular conclusion.
The idea is thatsome universal properties need not be instantiated. Itmay be true that 'all trespassers will be shot' even ifthere are no trespassers. It may be true that 'all brakelesstrains are dangerous' even though there are no brakelesstrains. That is the point of this fallacy.

Examples:
(i) All mice are animals, and all animals are dangerous, so some mice are dangerous.
(ii) No honest people steal, and all honest people pay taxes, so some homest people pay taxes.

Proof:
Assume that the premises are true, but that there are no instances of the category described. For example, in (i) above, assume there are no mice, and in (ii) above, assume there are no honest people. This shows that the conclusion is false