 Reichenbach’s technical argument is an adaptation of Henri Poincaré’s results on probability functions and what have since come to be called “strike ratios” (Poincaré, 1912, pp. 148–150). By considering events collected in a histogram, in which alternate equally narrow columns are black and white, Reichenbach argues that as the number of (independent) events increases (and the width of the columns decreases) the ratio of black to white events within any interval of the abscissa will approximate 1. Reichenbach’s general idea is that if a variable X is divided into two or more classes of very small intervals of equal width (in X units) juxtaposed in a definite order and proportion, then there will be a probability for the occurrence of a value of X within any particular class that is invariant over all Riemann integrable probability distributions for X. (The Riemann integral of a function describing a curve is defined as the limit of the sum of rectangles touching the curve as their width approaches 0.)