 A further problem is that the theory appears either to collapse into the causal theory or to make remembering into something quite mysterious. As Deutscher (1989) points out, there would seem to be no plausible story about what it is to retain knowledge that does not appeal to the sort of causal connection posited by the causal theory. Thus, if the epistemic theorist explicates retention of knowledge in terms of causal connection, then his theory collapses into the causal theory, and, if the epistemic theorist refuses to explicate retention of knowledge in terms of causal connection, then his theory fails to provide any real insight into the nature of remembering.