As a result of our investigation thus far, we have developed a view of numbers as a set of species-specific mental tools, and we have characterised counting words as verbal manifestations of this toolkit and as the first numbers our species might have grasped. In the previous chapter, identified language as that human faculty which gave us the mental background to develop a systematic number concept. I suggested a route to number in human evolution which started from iconic representations of cardinality, went via finger tallies and iconic sequences of words, and led to cardinal number assignments as the first context in which counting words might have been used as genuine numerical tools. Let us now have a look at the emergence of number not in human history, but in the individual development of children. What does the picture look like here? What route do children take when they acquire a systematic concept of number?

The present chapter is dedicated to these questions. In particular I will discuss the acquisition of cardinal number assignments, relating our view of counting words and number contexts to the psychological evidence for their representation in individual development. I show what role the numerical status of counting words plays in their acquisition, and how children learn to apply them to empirical objects for the first time. Again, we will find initial stages of iconic cardinality representations, and will see how the development of the language faculty supports the emergence of genuine number assignments.