 The Principle of Conditionalization requires one to react to new evidence by conditionalizing on it. So this principle, when construed literally, appears to be silent on the case in which one receives no new evidence. That is, it seems to be too weak to require that one shouldn’t arbitrarily change credences when there is no new evidence. To remedy this, the Principle of Conditionalization is usually understood such that the case of no new evidence is identified with the limiting case in which one acquires a logical truth as trivial new evidence, which rules out no possibilities. In that case, conditionalization on the trivial new evidence lowers no credences, and thus rescales credences only by a factor of 1—no credence change at all—as desired. Once the Principle of Conditionalization is construed that way, it is no longer too weak, but then the worry is that it becomes too strong. Consider the following case, which Earman (1992) adapts from Glymour (1980):