Not irrational by their own lights. "Take the action such that an unanticipated local miracle causing me to perform that action would be at least as good news as local miracles causing me to perform any of the alternative actions" is a coherent normative principle, even though such miracles do not occur. Other principles with different miracles are coherent too. Arguments for one decision theory or another only make sense for humans because we aren't clean implementations of any of these theories, and can be swayed by considerations like "agents following this rule regularly get rich."