 In Pollock 1995, Pollock uses a directed graph to represent the structure of an ideal cognitive state. Each directed link in the network represents the first node’s being a prima facie reason for the second. The new theory includes an account of hypothetical, as well as categorical reasoning, since each node of the graph includes a (possibly empty) set of hypotheses. Somewhat surprisingly, Pollock assumes a principle of monotonicity with respect to hypotheses: a belief that is warranted relative to a set of hypotheses is also warranted with respect to any superset of hypotheses. Pollock also permits conditionalization and reasoning by cases.