Consider the following premises. Sarah is not an electrician. Thomas is curious. If James goes running, then Sarah is an electrician. If William writes a letter, then James is running. If Sarah were an electrician, then James is running. Can we infer the following from them? If we can, name the inference rule being used: William is writing a letter.
 From the fact that if James goes running, then Sarah is an electrician, and that if Sarah were an electrician, then James is running we can infer that James is running if and only if Sarah is an electrician via biconditional introduction. From the fact that James is running if and only if Sarah is an electrician, and that Sarah is not an electrician we can infer that James is not running via biconditional elimination. Finally, from the fact that if William writes a letter, then James is running, and that James is not running we can infer that William is not writing a letter via modus tollens, which contradicts that William is writing a letter. Therefore, the answer is no.