Consider the following premises. James is a mechanic if and only if Robert is a scientist. Joseph is not driving a car. If James were a mechanic, then Robert is not excited. Joseph is driving a car. Can we infer the following from them? Robert is not a scientist.
 From the fact that Joseph is driving a car we can infer that Joseph is driving a car or Robert is excited. From the fact that Joseph is driving a car or Robert is excited, and that Joseph is not driving a car we can infer that Robert is excited. From the fact that if James were a mechanic, then Robert is not excited, and that Robert is excited we can infer that James is not a mechanic. Finally, from the fact that James is a mechanic if and only if Robert is a scientist, and that James is not a mechanic we can infer that Robert is not a scientist. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.