“Heuristic ordinarily has the meaning of “that which leads to discovery and invention.” … The primary heuristic has two features that are worth noting. One is that it takes the logical form of induction, generalizing into the future what worked in the past. That is, the successful variants are fed back into the gene pool, where they will be available for sampling by future generations. This is the conservative, pragmatic part of the heuristic. The other is the generation of novel variants by chance processes. This is the radical, inventive component of the heuristic. It is nature’s way of injecting new components into the system in order, possibly, to make up for the deficiencies that may occur if what worked in the past no longer does so because the world has changed.”