The mental model is the arena where imagination takes place. It enables us to experiment with different scenarios by making local alterations to the model. Somewhere in our hunters’ mental model was a subroutine that evaluated the effect of the number of hunters. When they considered adding more, they didn’t have to evaluate every other factor from scratch. They could make a local change to the model, replacing “Hunters = 8” with “Hunters = 9,” and reevaluate the probability of success. This modularity is a key feature of causal models.
