There is a simple view of motivation on which desires are like pain-killers; they come in different strengths, and their strength determines their efficacy. That is, the stronger a desire the greater its motivational force and, when two desires conflict, the stronger one “wins out” over the weaker. This view makes it puzzling how anyone could ever exhibit “strength of will” and act on the weaker desire, even when it is a desire for something more highly valued than what is (...) more strongly desired. When the will, as the agent of reason, enters the fray, an explanation of what a person is motivated enough to do must reckon not only with competing desires and their motivational forces, but also with the will’s capacity to be affected by different ones in ways not proportional to their force. However, this complication sheds little light, for if the will must bestow its stamp of approval on a desire before the desire leads to action, then, it would seem, motivational force should be measured by strength of effect on the will. And if that’s the way to measure motivational force, then, since by that measure one always acts on the desire that affects one’s will most, there is no problem of strength of will after all. But the problem seems real, however inapt the label. (shrink)