Consider the following premises. If Jennifer were a doctor, then Elisabeth is writing a letter. Jennifer is a doctor. Elisabeth is not writing a letter. Can we infer the following from them? Robert is an electrician.
 From the fact that if Jennifer were a doctor, then Elisabeth is writing a letter, and that Elisabeth is not writing a letter we can infer that Jennifer is not a doctor. From the fact that Jennifer is a doctor we can infer that Jennifer is a doctor or Robert is an electrician. Finally, from the fact that Jennifer is a doctor or Robert is an electrician, and that Jennifer is not a doctor we can infer that Robert is an electrician. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.