 Tension or conflict can also exist between doxastic obligations of a diachronic sort. The epistemic norm to gather as much evidence as possible may conflict with the prudential norm to believe in such a way as to save time and effort (example: the fastidious boss who never hires anyone until he has investigated a candidate's entire past, called every reference, and confirmed every qualification). It also conflicts with the moral norm not to believe on the basis of evidence gathered in an immoral fashion (example: the doctor who gathers evidence about human diseases by performing inhumane experiments on prisoners).