Consider the following premises. Barbara is a mechanic if and only if Joseph is drinking water. Barbara is not a mechanic. If James were a lawyer, then Joseph is drinking water. Can we infer the following from them? James is not a lawyer.
 From the fact that Barbara is a mechanic if and only if Joseph is drinking water we can infer that if Joseph drinks water, then Barbara is a mechanic. From the fact that if James were a lawyer, then Joseph is drinking water, and that if Joseph drinks water, then Barbara is a mechanic we can infer that if James were a lawyer, then Barbara is a mechanic. Finally, from the fact that if James were a lawyer, then Barbara is a mechanic, and that Barbara is not a mechanic we can infer that James is not a lawyer. Therefore, the answer is yes.