ABSTRACT
Let us begin by declaring two assumptions. We assume that (1) there is genuine cognitive development and (2) the process is psychological in nature. To some these hypotheses will seem bold, if not fanciful, since it is far from clear that there can be a psychological account of cognitive development. To others the assumptions will appear nebulous because there are no secure criteria for discriminating what is cognitive and what is psychological. Despite the broad range of opinion, there would seem to be a certain underlying consensus. It is generally accepted that the problem of cognitive development, no matter how it may be resolved, can only be understood in terms of concepts. If anything develops, it must be concepts; they are the natural measure of development. Accordingly, it is felt that the process of development, if there is such a process, must be interpreted as a process of concept learning.
