 On the other hand, if you regard the occasional use of recreational drugs as harmless fun that expresses a healthy contempt for overweening state authority (in some states, at least), then it might be prudent for you—confronted with the telltale odor—to form the belief that your son has indeed taken up the habit in question. Either way, the recommendation here aims at a kind of prudential or pragmatic value, and not at the truth per se. (For some recent arguments in favor of prudential evidence for belief, see Reisner 2008 and 2009; for arguments against, see Adler 2002 and Shah 2006). 