Kant's doctrine of the highest good is part of a broader philosophical agenda that is expressed by his famous slogan "I had to deny knowledge in order to make room for faith" (KrV Bxxx). As Kant argues in the first Critique, any attempt to gain knowledge of God, the human soul, and freedom of the will is doomed to fail. What is more, since these objects transcend the limits of possible experience, we are not even entitled to form scientific hypotheses or opinions about them. 1 However, as moral agents, we are justified in holding the Belief that God exists, that the human soul is immortal, and that we have free will. And what justifies this moral Belief is a genuinely practical consideration -a consideration about the way in which we might realize the highest good. 2 Kant's agenda is based on a novel account of the traditional distinction between opining (Meinen), Believing (Glauben), and knowing (Wissen). 3 According to Kant's rationalist predecessors, the three attitudes present different grades on an ascending scale of epistemic justification. Roughly speaking, the rationalists associate opinion with probabilistic justification, Belief with testimony, and knowledge with demonstrative reasoning. 4 By contrast, Kant's agenda presupposes that the attitude of Believing differs in a 1 See KrV A769-75/B797-803, A827/B855; KU 5:465f. 2 See KrV A810-14/B838-42, A828/B856; KpV 5:142ff.; KU 5:447ff. 3 The term Glauben, as Kant uses it, is notoriously difficult to translate. 'Faith' is too narrow since, in principle, Glauben is not restricted to matters of faith. 'Belief' is problematic as well. For one thing, it is controversial whether Glauben, as Kant understands it, involves outright belief, as opposed to what some recent philosophers have called 'acceptance' (see Chignell 2007a: 37; Chignell 2007b: 335). Moreover, Kant thinks that Wissen and Glauben are mutually exclusive. If you know that p, you cannot glauben that p, and vice versa. Thus to avoid misunderstanding, I shall follow Chignell (Chignell 2007b: 335n.) and write "Belief" with a capital B. 4