Recently, I encountered a question regarding syllogisms, where I was given one of the conclusions like

All Police men are not honest.


All Police men can never be honest.

But for me it seems that above sentences are ambiguous. Aren't they?

I thought former sentence implies that Some Police men are honest.

But I was wondering, if it could mean No Police men is honest.

Same confusion with latter sentence also. I couldn't find any explanations regarding this sentence.

If I'm wrong please explain to me the actual meaning.

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    Pretty much any sentence can be ambiguous outside a particular communicative discourse, especially when speaker's intent is not taken into consideration. Only if it is the speaker's intent for his or her sentence to be taken as a logic puzzle is this question close to being about the English language and not about logic, which follows a different set of rules. In other words, you cannot apply the rules of logic to everyday English sentences uttered in a discourse for a communicative purpose. Commented Sep 18, 2016 at 16:33
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    Thus the "meaning" of All policeman are not honest as far as the English language goes is dependent on what the speaker was trying to communicate with that sentence in the discourse in which he or she said it. Commented Sep 18, 2016 at 16:36
  • @AlanCarmack So, can't we say any particular meaning for the sentence, in general? Commented Sep 18, 2016 at 16:43
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    If you want to treat the sentence as a logic puzzle, you can. If you want to dissect the sentence devoid of any discourse context or speaker's intention, you can. But that is not how language works. It really depends on what the speaker meant when he uttered the sentence in a given discourse context, and for a given purpose, and to fulfill a function, in order to look at the sentence as a means of communication, which is what language is. Commented Sep 18, 2016 at 16:52
  • If you are asking whether a given sentence aptly sums up a text or argument that is a language question. Commented Sep 18, 2016 at 16:56

1 Answer 1


Since you mention "syllogism" I'll treat this a sentences in formal logic, rather than natural language.

"All policemen are not honest" is equivalent to "The set of policemen is a subset of the set of not honest things" or, since "not honest" and "honest" are mutually exclusive, it is equivalent to "the set of honest policemen is empty"

In regular language it mean that "No policemen are honest"

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    But: this is not the same proposition as "Not all policemen are honest" Commented Sep 18, 2016 at 16:52

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