Ex ante decision analysis has other problems than ex post analysis. One of the problems is the nature of the value system of the deciding person. Mostly, it will contain different values (criteria, points of view) which are not reducible to one measure. These cases of incommensurability are one reason for the incomparability of the decision options. There are other reasons why it seems highly unrealistic that we may assume the comparability of options as a general case for a rational decision maker.