Contradiction and Consent in Kant’s Ethics

Abstract

Let us examine the contradiction test for morally permissible maxims of action, which Kant associates with the formula of universal law in the Groundwork of the Metaphysics of Morals. We will not take up the details of precisely how the contradiction test should be interpreted. Instead, after considering some problems with the contradiction test, we will determine whether or not the contradiction test is needed and why Kant uses the test if it is so problematic. Could Kant simply avoid problems with the contradiction test by using the formula of humanity instead to decide what is right and wrong, as some recent writers on Kant, such as Derek Parfit and Barbara Herman, would prefer? As we will see, the formula of humanity in fact cannot be separated from the contradiction test without compromising some of Kant’s deepest commitments. In particular, Kant’s views about the nature of autonomy and happiness require him to use the contradiction test as his criterion of right and wrong, and prevent him from using the formula of humanity independently of the contradiction test.