Piaget's theory has recently been criticized by Wartofsky (1983) for failing to adapt to new information and ideas in the field of cognitive development: there has been too much assimilation and not enough accommodation. This amounts to a criticism that the theory is no longer capable of growth. Wartofsky calls for a historical epistemology, rather than a genetic epistemology, because phylogenesis, in cognitive terms, can no longer be seen to be biologically fixed. It is historical, cultural and it continues. From this it follows that ontogenesis is not the socialization of child-thought to a fixed adult world, but to a changing world. Thus, Piaget cannot determine those universal and necessary features of the growth of knowledge, because this assumes a fixed species as the norm. What is needed, according to Wartofsky, is an evolutionary theory of the history of cognition. Implicit in this is the need for Piagetian theory to accommodate to new ideas and theories in order to develop and progress, and there is an implied criticism that this has not occurred.