 While the plan version of the Conditionalization Principle is weak enough to avoid the Physics Student counterexample, it might be worried that it is too weak. There are actually two worries here. The first worry is that the plan version is too weak because it leaves open an important question: Even if one’s plan for credence change is always a plan to conditionalize on new evidence, should one actually follow such a plan whenever new evidence is acquired? For discussions of this issue, see Levi (1980: ch. 4), van Fraassen (1989: ch. 7), and Titelbaum (2013a: parts III and IV). (Terminological note: instead of ‘plan’, Levi uses ‘confirmational commitment’ and van Fraassen uses ‘rule’.) The second worry is that the plan version is too weak because it only avoids the problem of new theory, without giving a positive account as to why the student’s credence in the old theory ought to drop.