The philosophy of social science is more heavily intertwined with actual social science than in the case of other subjects such as physics or mathematics, since its question is centrally whether there can be such a thing as social science. The idea of a ‘science of man’, devoted to uncovering scientific laws determining the basic dynamics of human interactions was a cherished ideal of the Enlightenment and reached its heyday with the positivism of writers such as Comte, and the historical materialism of Marx and his followers. Sceptics point out that what happens in society is determined by peoples’ own ideas of what should happen, and like fashions those ideas change in unpredictable ways as self-consciousness changes. They also point out that this self-consciousness is susceptible to change by any number of external events; unlike the solar system of celestial mechanics a society is not at all a closed system evolving in accordance with a purely internal dynamic, but constantly responsive to shocks from outside.