<P> American philosopher Louis Pojman has cited Pietism, political philosopher Jean - Jacques Rousseau, the modern debate between rationalism and empiricism, and the influence of natural law as influences on the development of Kant's ethics . Other philosophers have argued that Kant's parents and his teacher, Martin Knutzen, influenced his ethics . Those influenced by Kantian ethics include philosopher Jürgen Habermas, political philosopher John Rawls, and psychoanalyst Jacques Lacan . German philosopher G.W.F. Hegel criticised Kant for not providing specific enough detail in his moral theory to affect decision - making and for denying human nature . German philosopher Arthur Schopenhauer argued that ethics should attempt to describe how people behave and criticised Kant for being prescriptive . Michael Stocker has argued that acting out of duty can diminish other moral motivations such as friendship, while Marcia Baron has defended the theory by arguing that duty does not diminish other motivations . The Catholic Church has criticised Kant's ethics as contradictory and regards Christian ethics as more compatible with virtue ethics . </P> <P> The claim that all humans are due dignity and respect as autonomous agents means that medical professionals should be happy for their treatments to be performed on anyone and that patients must never be treated merely as useful for society . Kant's approach to sexual ethics emerged from his view that humans should never be used merely as a means to an end, leading him to regard sexual activity as degrading and to condemn certain specific sexual practices - for example, extramarital sex . Feminist philosophers have used Kantian ethics to condemn practices such as prostitution and pornography because they treat women as means . Kant also believed that, because animals do not possess rationality, we cannot have duties to them except indirect duties not to develop immoral dispositions through cruelty towards them . Kant used the example of lying as an application of his ethics: because there is a perfect duty to tell the truth, we must never lie, even if it seems that lying would bring about better consequences than telling the truth . </P> <P> Although all of Kant's work develops his ethical theory, it is most clearly defined in Groundwork of the Metaphysics of Morals, Critique of Practical Reason and Metaphysics of Morals . As part of the Enlightenment tradition, Kant based his ethical theory on the belief that reason should be used to determine how people ought to act . He did not attempt to prescribe specific action, but instructed that reason should be used to determine how to behave . </P> <P> In his combined works, Kant constructed the basis for an ethical law by the concept of duty . Kant began his ethical theory by arguing that the only virtue that can be unqualifiedly good is a good will . No other virtue has this status because every other virtue can be used to achieve immoral ends (the virtue of loyalty is not good if one is loyal to an evil person, for example). The good will is unique in that it is always good and maintains its moral value even when it fails to achieve its moral intentions . Kant regarded the good will as a single moral principle which freely chooses to use the other virtues for moral ends . </P>

Which of the following is also known as the kantian tradition in ethics