Suppose an accountant discovers evidence of shady practices while ex- amining the books of a client. What should he or she do? Accountants have a professional obligation to respect the confidentiality of their cli- ents' accounts. But, as an ordinary citizen, our accountant may feel that the authorities ought to be informed. Suppose a physician discov- ers that a patient, a bus driver, has a weak heart. If the patient contin- ues bus driving even...