  Even nonautonomous rational agents authorize the motivating power of the desires that move them to act. Yet there is an important sense in which the power behind their authorizations is not their own. What does the relevant impotence amount to? The incompatibilist, we saw, has a ready answer: an agent is prevented from exercising any power over her behavior when her authorization of this behavior can be traced to the determining influence of external powers. According to the incompatibilist, if the unwilling addict fails to govern herself, this is because her motives are determined by past states of affair over which she does not have (and never did have) any control. And if a willing addict’s motives have a similar genesis, then she, too, is not accountable for their motivating power.