means the same as:
Formally:
¬ ¬ A ∴ A
Also:
¬ ¬ ¬ A ∴ ¬ A
The rule of double negative introduction[?] states the converse, that double negatives can be added without changing the meaning of a proposition.
This rule is true in classical logic, but in intuitionistic logic, the statement, It's not the case that it's not raining. is weaker than It's raining.. As a more clearer example, It's not unreasonable is slightly less direct than It's reasonable.
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