 Put more generally: if you have a prudential end E, and belief that p is likely to make E obtain, then you have a prima facie obligation to believe that p. The obligation will be particularly powerful (though still prima facie) if E cannot be achieved other than through belief that p, and if you are (or should be) aware of that fact. (For more on hypothetical norms generally, see Broome 1999 and Schroeder 2005)