Bill doesn’t run or swim.
Bill doesn’t run and doesn’t swim.
What is the difference in meaning between these two sentences?
asked May 14, 2020 at 10:12
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2This is a case where English does follow the rules of formal logic: not (A or B) = (not A and not B)– Colin FineCommented May 14, 2020 at 11:09
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Are “doesn’t run and swim” and “doesn’t run and doesn’t swim” same?– ramteja guthikondaCommented May 14, 2020 at 11:52
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1No, because doesn't run and swim is ambiguous. It could mean "doesn't do both at the same time", or it could mean the same as "doesn't run and doesn't swim". That is a case where English does not reliably follow the rules of formal logic.– Colin FineCommented May 14, 2020 at 14:09
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@ColinFine Of course, in formal logic (not A) and (B) and not(A and B) are completely different things. It is not so much that English does not follow the rules of formal logic as that it does not have the tools to use "and" with the subtlety of formal logic.– Jeff MorrowCommented Jul 17, 2022 at 20:12
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@JeffMorrow: So you're saying that a natural language "doesn't have the tools" to be something which isn't a natural language. English also doesn't have the tools to use a paintbrush with the subtlety of a painter.– Colin FineCommented Jul 17, 2022 at 20:39
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2 Answers
In your particular case, they are the same. however normally you wouldn't use 'and' in this case, as it's a more complex sentence structure.
How 'and' would normally be used, would be as both happening together. Like "John doesn't drink and drive." This doesn't mean he doesn't do either in their own, just that he doesn't drink while driving (or shortly before would be implied).
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So you mean, “Bill doesn’t run and swim” means he don’t run and swim simultaneously or he don’t swim after running? @Michael Commented May 14, 2020 at 11:51
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It could be understood to mean 'He doesn't run and swim at the same time', although of course that would not be possible for anyone. Commented May 14, 2020 at 13:07
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“John lost his driving license for drink driving.” “That’s impossible. I know for a fact that John doesn’t drink or drive.” - I gave two reasons why the first statement cannot be true. He doesn’t drive, so he can’t get caught drunk driving. And he never, ever drinks. Commented Nov 8, 2021 at 11:14
Bill doesn't run or swim = Bill doesn't run. Bill doesn't swim.
Bill doesn't run and swim. ---> Bill doesn't run and swim at the same time. (It's not possible too.)
Bill doesn't run, and he doesn't swim, either. (Bill doesn't run and doesn't swim.) = Bill doesn't run. Bill doesn't swim.
But this sentence is long and cumbersome, so the shorter negative sentences with 'or' are preferable.
answered May 14, 2020 at 15:37
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I'd say that your second sentence is ambiguous. It would be taken either way– KevinCommented Jun 25, 2020 at 13:28
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"Bill doesn't drink and drive" ---> Bill doesn't drink, then drive. So it's not clear that "and" will be understood to mean simultaneity. Commented Mar 19 at 17:51