 Wolfgang Spohn (Spohn 2002) has argued that Pollock’s system is normatively defective because, in the end, Pollock has no normative standard to appeal to, other than ad hoc intuitions about how a reasonable person would respond to this or that cognitive situation. Spohn suggests that, with respect to the state of development of the study of defeasible reasoning, Pollock’s theory corresponds to C. I. Lewis’s early investigations into modal logic. Lewis suggested a number of possible axiom systems, but lacked an adequate semantic theory that could provide an independent check on the correctness or completeness of any given list (of the kind that was later provided by Kripke and Kanger). Analogously, Spohn argues that Pollock’s system is in need of a unifying normative standard. This very same criticism can be lodged, with equal justice, against a number of other theories of defeasible reasoning, including semantic inheritance networks and default logic.