Consider the following premises. John is a writer if and only if it is windy. John is a writer if and only if it is windy. Can we infer the following from them? If we can, name the inference rule being used: The fact that John were a writer does not imply that it is windy.
 From the fact that John is a writer if and only if it is windy we can infer that if it is windy, then John is a writer via biconditional elimination. Finally, from the fact that John is a writer if and only if it is windy we can infer that if John were a writer, then it is windy via biconditional elimination, which contradicts that The fact that John were a writer does not imply that it is windy. Therefore, the answer is no.