  Someone displays instrumental rationality insofar as she adopts suitable means to her ends.  Instrumental rationality, by virtually any reckoning, is an important, and presumably indispensable, part of practical rationality.  However, philosophers have been interested in it for further reasons.  To take one example, it has been suggested that instrumental rationality, or some tendency toward it, is partly constitutive of intention, desire, or action. To take another, more important, example, it has been argued that instrumental rationality is not only a part, but a special part, or even the whole, of practical rationality.  This thesis appears to threaten the “rational authority” of morality.  It seems possible that acting morally on some occasion might not be a suitable means to an agent’s ends.  If so, then according to this thesis, it would not be irrational for her to refuse to act morally on such an occasion. 