In the last chapter, we saw how empirically observed period-doubling leading to apparent chaos might be explained (or at least, be partially explained). For we can show why period-doubling is endemic in a wide class of cases where other marks of chaos are also present. The relevant mathematics is intriguing; but on the face of it there seems nothing exceptional about the way that it may be brought to bear in explaining the phenomena. True enough, the modellings we are working with are often very partial and extremely idealized and perhaps (at this stage in the game) rather lacking in detailed physical motivation: but then, that's common enough in frontier science.

What goes for the explanations of period-doubling goes too, I claim, for other explanations in applied chaos theory. The new mathematical models may be distinctive; but the sort of explanations which their application yields is not. However, philosophers writing on chaos have repeatedly argued otherwise – they have claimed that there is something rather special about the explanations delivered by chaotic dynamical theories. Such explanations have variously been described as being characteristically ‘ex post facto’, ‘qualitative’, ‘holistic’ (or ‘anti-reductionist’), and ‘experimentalist’; it has also been suggested that we should recognize here a rather distinctive ‘Q-strategy’ of explanation. But why so?

Suppose it is maintained, first, that prediction and standard modes of explanation go together – roughly, a standard explanation after the event deploys materials that, before the event, could have been used to frame a prediction.