Chapter 10 shows that Kierkegaard develops his views on faith and reason by using classical German philosophy from Leibniz to Kant. Specifically, he develops the much-discussed category of the leap by making creative use of Jacobi and Lessing. The result is an original account of the leap relevant to both philosophy of religion and more general debates concerning rationality, incommensurability, and noncommensurability. Specifically, the “leap” concerns both general transitions between different normative standards and religious conversions in particular. Even when different standards diverge and conflict, such leaps need not be blind or irrational, if one abandons standards that collapse internally, and the new standards hold up. This general approach allows Kierkegaard to sketch a Kantian reductio of religious nonbelief. However, he appears to follow Schelling in taking Kant’s critique of the ontological argument for God’s existence to show that being is not a predicate, and that thought and being, possibility and actuality, are therefore heterogeneous. Whether or not something exists is then a contingent matter that cannot be known a priori.