 When we have negation and conjunction, it is important to keep the order in the right way. “It is not sunny and it is not windy” is different from “It is not the case that it is sunny and windy”. Hence, the sentence “It is not the case that it is sunny and it is windy” is ambiguous, depending on the scope of “it is not the case”. In the case of sentential logic, parentheses get in to prevent this ambiguity: \(\neg (S \land W)\) versus \(\neg S \land W\). Peirce’s warning follows: