 One objection to the argument from error is that another type of objective reality, some other sort of being external to one’s finite mind, might explain the possibility of error just as well. Royce took up this objection in the first volume of The World and the Individual, which was subtitled “The Four Historical Conceptions of Being.” In this extended argument Royce critiqued what he regarded as the main competing conceptions of objective reality so as to strengthen his case for idealism. The first conception of being Royce considered was realism, the view that the world exists entirely independently of our thoughts or ideas about it. The world is what it is, in short, without any reference to our thoughts. While this view has great common-sense appeal and does provide for an objectively existing sphere of being against which our ideas can apparently be measured, Royce pointed out a fundamental problem. Realism, so defined, introduces a radical metaphysical dualism. Between my ideas, and a sphere of being that by definition exists completely independent of those ideas, there is a gap that cannot be bridged. Realism posits an objective realm that is utterly independent and hence, strictly speaking, is utterly meaningless to thought. The theory of mysticism, the second conception of being Royce considered, likewise meets with problems. This view maintains that the real is the ineffable immediate fact that is present to the mind. Mysticism avoids the problem of an unbridgeable gap between idea and reality by completely denying any such gap. The difficulty here is that one cannot then distinguish between idea and reality. If reality is in the end the immediate content of my idea, then error in my idea of reality would simply appear to be impossible. The third conception of being, which Royce identified with Kantian critical rationalism, is presented as a correct but incomplete view. Royce characterized critical rationalism as the view that “What is, gives warrant to ideas, makes them true, and enables us to define determinate, or valid, possible experiences” (Royce 1899–1901 [1976, 266]). The real is that which, in conforming to given universal structures or categories of experience, is capable of validating certain ideas. The connection between my ideas and an objectively existing sphere of being is clearly established: my ideas and that sphere both conform to the same categories of experience. The independence of objective reality, and hence the possibility of error, is likewise preserved: I may form an idea of a definite possible experience (e.g., that my keys are on the table) but then discover that reality does not validate my idea (I can in fact check the table surface and discover that my keys are not there). The critical rationalist conception is inadequate, in Royce’s view, because it is restricted to describing the universal forms and possibilities of experienced reality. It cannot in Royce’s view account for the concrete, actual individual facts that impose themselves in experience. These are simply and mysteriously “given” in the critical rationalist theory.