Figure 1. The challenges presented by number learning.

This picture contains nine objects: one red ball, two hats, three balls and four bears; there are more bears than balls or hats, fewer hats than balls, and more balls and hats than bears. Somehow, a child must discern the cues that discriminate between appropriate and inappropriate usage of each word. Unless one assumes that children's vocabulary is innate, this problem will have to be solved even if children are granted some innate representation of number. That is, even if children have some internal concept of two, they still need to map the presence of two things in the environment to the word “2” and not to, say, “3,” which might be heard in the same context.