What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_15, if x_15 listens to a song, then x_15 is a doctor. For all x_15, if x_15 were a doctor, then x_15 is listening to a song. William is not listening to a song. William is a doctor.
Since the premises are contradictory, we can infer anything from them.