 But Elga (2000) argues that the answer is \(1/3\) rather than \(1/2\). If so, that will seem to be a counterexample to the Principle of Conditionalization. Here is a sketch of his argument. Imagine that we are Sleeping Beauty and reason as follows. We just woke up, and there are only three possibilities on the table, regarding how the coin landed and what day it is today: