In light of such considerations, many philosophers have argued that Hume doesn’t endorse an instrumentalist conception of practical reason, but instead, more radically, is a skeptic about all of practical reason.  (See, for instance, Hampton 1995; Millgram 1995; Korsgaard 1997.  For objections to this skeptical interpretation of Hume, see Setiya 2004.)  On this interpretation, Hume acknowledges the existence of requirements of theoretical reason, since beliefs can be assessed as reasonable or unreasonable, but is skeptical about the existence of requirements of practical reason, including instrumental reason, since desires, intentions, and actions can’t be assessed as reasonable or unreasonable.  (Even a preference for “one’s own acknowledg’d lesser good” wouldn’t be unreasonable, on his view.)  Since, on this interpretation, Hume was skeptical about practical reason in general, we can’t appeal to his view to establish a special place for instrumental rationality among the requirements of practical rationality. 