Readings: von Mises

"If it should be thought that index numbers offer us an instrument for providing currency policy with a solid foundation and making it independent of the changing economic programmes of governments and political parties, perhaps I may be permitted to refer to what I have said in the present work on the impossibility of singling out any particular method of calculating index numbers as the sole scientifically correct one and calling all the others scientifically wrong. There are many ways of calculating purchasing power by means of index numbers, and every single one of them is right, from certain tenable points of view; but every single one of them is also wrong, from just as many equally tenable points of view. Since each method of calculation will yield results that are different from those of every other method, and since each result, if it is made the basis of practical measures, will further certain interests and injure others, it is obvious that each group of persons will declare for the methods that will best serve its own interests. At the very moment when the manipulation of purchasing power is declared to be a legitimate concern of currency policy, the question of the level at which this purchasing power is to be fixed will attain the highest political significance."
Ludwig von Mises, preface to the English edition of The Theory of Money and Credit (1934)