Dreier (2001) concludes that the instrumental analogue of Carroll’s paradox shows that instrumental rationality has a special status.  In Carroll’s original paradox, the Tortoise would be such that we couldn’t give him reasons to believe in some proposition.  In the normal case, I can provide you with a reason to believe Q by getting you to believe P and to believe P→Q.  But this simply won’t work for the Tortoise, who refuses to apply modus ponens.  Likewise, Dreier observes, we would be incapable of giving reasons to someone who refused to draw “practical inferences” between ends and means.  The acceptance of instrumental rationality is thus, he argues, a necessary condition for being receptive to reasons at all.  And this supports his conclusion that “the only ultimate sort of reasons are instrumental reasons” (p.  43).  This seems to be an endorsement of the Desire-Based Theory. 