 But here is a simple objection to this three-part doctrine, borrowed from Descartes’s famous “dream skepticism” in the first of the Meditations on First Philosophy. Kant calls this form of skepticism “problematic idealism” (B274). To generate the relevant version of problematic idealism, suppose that all the sensory appearances or objects currently falling under the Second Analogy, the criterion of empirical truth, and the principle of transcendental truth are nothing but causally well-ordered parts of my inner sense alone. Then any object of experience corresponding to my currently true judgment of experience might be nothing but a very coherent dream or a hallucination. Nothing Kant has said can rule this out. Even the famous Refutation of Idealism in the first Critique, if sound, says only that “inner experience is possible only through outer experience in general” (B278–279), and Kant explicitly concedes that at any given time, for all we know, we could be dreaming or hallucinating: