1999 年 1999 巻 50 号 p. 294-304
Among methods for representing our belief states and belief changes, Bayesianism is one of the most popular methods. Bayesianism has two features :
1. Our rational belief states can be represented by probability functions.
2. Our rational belief changes can be represented by the conditionalization of probability functions.
We can derive conditionalization from the more general principle. It is the Principle of Minimum Relative Information (PMRI). Van Fraassen shows that PMRI is inadequate as a method of rational belief changes because it doesn't give a rational solution to JB problem. On the contrary to his argument, I will prove that PMRI can give a rational solution to JB problem.