 Even if there is not something radically new here regarding scientific explanation, the kind of understanding provided by chaos models is challenging to clarify. One problem is that this “dynamic understanding” appears to be descriptive only. That is, Kellert seems to be saying we understand how chaos arises when we can point to a period doubling sequence or to the presence of a strange attractor, for instance. But this appears to be only providing distinguishing marks for chaos rather than yielding genuine insight into what lies behind the behavior, i.e., the cause of the behavior. Kellert eschews causes regarding chaos explanations and there is a fairly straightforward reason for this: The simplified models of chaos appear to be just mathematics (e.g., one dimensional maps) based on the original nonlinear equations. In other words, it looks as if the causes have been squeezed out! So the question of whether causal, unificationist or some other approach to scientific explanation best captures chaos research remains open. 