Walzer's Just and Unjust Wars utilizes a moral doctrine known as casuistry, which applies existing moral norms to practical cases while putting aside the actual origins of morality. Boyle contrasts Walzer's casuistry to other methods of moral judgment, including consequentialism, institutionalism, and deontology. He discusses deontology, which derives precepts from moral principles, particularly making a case with reference to Alan Donagan's The Theory of Morality, which appeared the same year as Just and Unjust Wars. Boyle cites casuistry as a highly practical method, but cautions that it is an insufficient guide in extreme situations for which there are no existing moral norms. Boyle points out that in cases where casuistry fails Walzer he turns to consequentialism, which bases moral decisions upon the likelihood that the benefit of an action will outweigh the harm. Boyle argues that such utilitarian calculation weakens the authority of the moral world by allowing exceptions to moral principles in times of emergency. He concludes that the method of rationalistic deontology provided by Donagan is preferable to Walzer's casuistry.