Harvard MBAs have proposed that all MBA students sign an oath. It pledges, among other things, to “contribute to the well-being of society” and to “create sustainable economic, social and environmental prosperity worldwide.” I don’t believe that this is a good idea, for three reasons. First, some parts of the pledge are inconsistent with fiduciary duties and ethical standards. Second the oath is a misplaced response to the financial crisis. Third, I don’t believe in pledges as an instrument to guide people’s behaviour.