Kerstein, Samuel’s Kant’s Search for the Supreme Principle of Morality (Cambridge, 2002) adopts an interpretive strategy for the Groundwork similar to mine, though we differ on what Kant’s criteria for the supreme principle of morality are. Kerstein, offers a condensed discussion of his strategy in “Deriving the supreme moral principles from common moral ideas,” in Hill, T.E. (ed.), Blackwell Guide to Kant’s Ethics (Wiley-Blackwell, 2009). Korsgaard, Christine’s “Kant’s analysis of obligation: The argument of Groundwork I,” The Monist 72 (1989): 311–340, particularly section III, indicates how the early portions of that text use a “motivational analysis” of the good will to identify morality’s supreme principle. Dancy, Jonathan’s Ethics Without Principles (Oxford, 2004) is the best-known articulation of particularism. Ross, W.D.’s classic The Right and the Good (Oxford, 2003) is the canonical source for modern-day ethical intuitionism.

Some influential discussions of the Formula of Humanity include Hill, Thomas, “Humanity as an end in itself,” Ethics 91 (1980): 429–450, and Korsgaard, Christine, “Kant’s Formula of Humanity,” Kant-Studien 77 (1986): 183–202. Dean, Richard offers a thorough examination of the place of humanity in Kant’s ethics in The Value of Humanity in Kant’s Moral Theory (Oxford, 2006). Glasgow, Joshua contests Dean’s interpretations in “Kant’s conception of humanity,” Journal of the History of Philosophy 45 (2007): 291–308. For contrasting defenses of the claim that rational agency is the sole source of unconditioned value, see Korsgaard, Christine, The Sources of Normativity (Cambridge, 1996) and Sussman, David, “The authority of humanity,” Ethics 113 (2003): 350–366. Baron, Marcia provides an excellent account of Kant’s taxonomy of duties in the contribution on Kantian ethics to Three Methods of Ethics: A Debate (Blackwell, 1997). Johnson, Robert takes a Kantian approach to duties to self in Self-Improvement: An Essay in Kantian Ethics (Oxford, 2011). Some of the more useful discussion of Kant on lying include James Mahon, “The truth about Kant on lies,” and Sussman, David, “On the supposed duty of truthfulness: Kant on lying in self-defense,” both in Martin, C. (ed.), The Philosophy of Deception (Oxford, 2009). Those seeking a deeper understanding of utilitarianism should consult J.S. Mill’s classic and widely reprinted essay “Utilitarianism,” as well as Smart, J.J.C. and Williams, Bernard’ Utilitarianism: For and Against (Cambridge, 1973) and Shaw, William’s Contemporary Ethics: Taking Account of Utilitarianism (Wiley-Blackwell, 1999).

Perhaps no topic within Kant’s ethics has received more attention from philosophers than the Formula of Universal Law. Onora O’Neil’s work has been very influential in guiding scholarly discussion of the universalization test. See Acting on Principle: An Essay on Kantian Ethics (Columbia, 1975; published under the name Onora Nell) and Constructions of Reason: Explorations of Kant’s Practical Philosophy (Cambridge, 1989), especially the essay “Consistency in action.” An equally influential discussion is Korsgaard, Christine’s “Kant’s formula of universal law,” Pacific Philosophical Quarterly 66 (1985): 24–47. There Korsgaard proposes three interpretations of the Formula of Universal Law: the Logical Contradiction Interpretation, the Teleological Contradiction Interpretation, and the Practical Contradiction Interpretation. The ‘rational contradiction’ interpretation I defended in this chapter is not identical to any of these, but most closely resembles the Practical Contradiction Interpretation. Galvin, Richard provides an excellent overview of the debates surrounding these rival interpretations in “The universal law formulas,” in Hill, T. (ed.), Blackwell Guide to Kant’s Ethics (Wiley-Blackwell, 2009). The ACE structure of maxims is well explained by Glasgow, Josh, “Kant’s principle of universal law,” in Timmons, M. (ed.), Conduct and Character, 5th edn. (Thomson Wadsworth, 2006). For a similar account of the structure of maxims, as well as some strategies for dealing with false negatives and various complicated maxims, see McCarty, Richard, “False negatives of the Categorical Imperative,” Mind 124 (2015): 177–200. Hill, ’s “The hypothetical imperative,” Philosophical Review 82 (1973): 429–450, is a good starting place for understanding the rational force of the hypothetical imperative and why Kant denied that the supreme principle of morality can be an instance of it. O’Neill, ’s “Universal laws and ends in themselves,” The Monist 72 (1989): 341–361, is a valuable discussion of the relationships between the Humanity and Universal Law Formulas.

Rosen, Michael’s Dignity: Its History and Meaning (Harvard, 2012) offers an excellent historical overview of how various religious and ethical traditions have come to shape how we understand the notion of dignity. Graaf, Riekeder and Jmdelden, Johannes, “Clarifying appeals to dignity in medical ethics from an historical perspective,” Bioethics 23 (2009): 151–160, is similarly useful. Kolnai, Aurel, “Dignity,” Philosophy 51 (1976): 251–271, is one of the first systematic philosophical attempts to make sense of dignity. Hill, Thomas is among the Kantian philosophers who have investigated Kant’s conception of dignity most thoroughly. See in particular his “Humanity as an end in itself,” Ethics 91 (1980): 84–99. Darwall, Stephen shows how dignity functions as an interpersonal or social moral ideal in “Why Kant needs the second-person standpoint,” in Hill, T. (ed.), Blackwell Guide to Kant’s Ethics (Wiley-Blackwell, 2009), pp. 138–158. Sensen, Oliver, Kant on Human Dignity (de Gruyter, 2011) is a comprehensive account of Kant on dignity that reaches different interpretive conclusions than I have in this chapter. Gentzler, Jyl, “What is a death with dignity?,” Journal of Medicine and Philosophy 28 (2003): 461–487, investigates the different notions of dignity at play in end-of-life ethics debates.

This chapter has only scratched the surface of the difficult issues raised by Kant’s understandings of freedom, will, morality, and their interrelations. Some resources that shed further light include Ameriks, Karl, “Kant’s deduction of freedom and morality,” Journal of the History of Philosophy 19 (1981): 53–79; Hill, Thomas E., “Kant’s argument for the rationality of moral conduct,” Pacific Philosophical Quarterly 66 (1985); Allison, Henry, Kant’s Theory of Freedom (Cambridge, 1990); Korsgaard, Christine, “Morality as freedom,” in her Creating the Kingdom of Ends (Cambridge, 1997), pp. 159–187; Reath, Andrews, “Kant’s critical account of freedom,” in Bird, G. (ed.), A Companion to Kant (Wiley-Blackwell, 2006), pp. 275–290; Uleman, Jennifer, An Introduction to Kant’s Moral Philosophy (Cambridge, 2010), chapter 4; and Schapiro, Tamar, “Foregrounding desire: A defense of Kant’s incorporation thesis,” Journal of Ethics 15 (2011): 147–167. Kleingeld, Pauline, “Moral consciousness and the ‘fact of reason,’” in Reath, A. and Timmermann, J. (eds.), Kant’s Critique of Practical Reason: A Critical Guide (Cambridge, 2010), pp. 55–72, is an excellent entry point for controversies about how to understand Kant’s “fact of reason.” A number of the essays in Guyer, Paul’s Kant on Freedom, Law, and Happiness (Cambridge, 2000) address Kant’s understanding of freedom. For varied views on Kant’s metaphysics and the noumena/phenomena distinction, see (among many others) Langton, Rae, Kantian Humility: Our Ignorance of Things in Themselves (Oxford, 2001); Allison, Henry, Kant’s Transcendental Idealism (Yale, 2004); and Grier, Michelle, Kant’s Doctrine of Transcendental Illusion (Cambridge, 2007).