  The philosopher, by contrast, is most able to do what she wants to  do, for she wants to do what is best, and as long as one has agency,  there would seem to be a doable best. (Should circumstances make a  certain apparent best undoable, then it would no longer appear to be  best.) But this is not to say that the philosopher is guaranteed to  be able to do what she wants. First, Socrates is quite clear that  some appetitive attitudes are necessary, and one can well imagine  circumstances of extreme deprivation in which the necessary  appetitive attitudes (for food or drink, say) are unsatisfiable.  Second, the capacity to do what is best might require engaging in  certain kinds of activities in order to maintain itself. So even if  the philosopher can satisfy her necessary appetitive attitudes, she  might be prevented by unfortunate circumstances from the sorts of  regular thought and action that are required to hold onto the  capacity to do what is best. Thus, even if a philosophical soul is  most able to do what it wants, and the closest thing to a sure bet  for this capacity, it does not retain this ability in every  circumstance.