Practical Reason, Aristotle, and Weakness of the Will was first published in 1984. Minnesota Archive Editions uses digital technology to make long-unavailable books once again accessible, and are published unaltered from the original University of Minnesota Press editions.

One of the central problems in recent moral philosophy is the apparent tension between the "practical" or "action-guiding" side of moral judgments and their objectivity. That tension would not exist if practical reason existed (if reason played a substantial role in producing motivation) and if recognition of obligation were one of the areas in which practical reason operated. In Practical Reason, Aristotle, and the Weakness of the Will,Norman Dahl argies that, despite widespread opinion to the contrary, Aristotle held a position on practical reason that both provides an objective basis for ethics and satisfies an important criterion of adequacy—that it acknowledges genuine cases of weakness of the will. In arguing for this, Dahl distinguishes Aristotle's position from that of David Hume, who denied the existence of practical reason. An important part of his argument is an account of the role that Aristotle allowed the faculty nous to play in the acquisition of general ends. Relying both on this argument and on an examination of passages from Aristotle's ethics and psychology, Dahl argues that Aristotle recognized that a genuine conflict of motives can occur in weakness of the will. This provides him with the basis for an interpretation that finds Aristotle acknowledging genuine cases of weakness of the will.

Dahl's arguments have both a philosophical and a historical point. He argues that Aristotle's position on practical reason deserves to be taken seriously, a conclusion he reinforces by comparing that position with more recent attempts, by Kant, Nagel, and Rawls, to base ethics on practical reason.