 Reichenbach applied his strategy to a general form of “statistical induction” in which we observe the relative frequency \(f_n\) of a particular event in n observations and then form expectations about the frequency that will arise when more observations are made. The “inductive principle” then states that if after a certain number of instances, an observed frequency of \(m/n\) is observed, for any prolongation of the series of observations, the frequency will continue to fall within a small interval of \(m/n\). Hume’s examples are special cases of this principle, where the observed frequency is 1. For example, in Hume’s bread case, suppose bread was observed to nourish n times out of n (i.e. an observed frequency of 100%), then according to the principle of induction, we expect that as we observe more instances, the frequency of nourishing ones will continue to be within a very small interval of 100%. Following this inductive principle is also sometimes referred to as following the “straight rule”. The problem then is to justify the use of this rule.