ABSTRACT
The scrutiny of past predictions will enable us to make an inventory of the mind's natural modes of proference. A little reflection will show that people have no reason for assuming an exact correspondence between the process of proference and the process of history. Simple, naive modes of proference, which make a particular future seem evident, sometimes go wrong. The trouble with prolongation of a tendency is that the reversal of the tendency is not anticipated. This comment is not intended to condemn extrapolation, but only to serve as a warning. Analogy is more rational than extrapolation. The "railway" perspective gives no forewarning of the revolution of 1848 or of the coup detat of December 2, 1851. The United Nations graph on which different countries are ranked on a dollar scale according to their national per capita income is ideally designed to foster the "railway" outlook.
