Elster's account was an exhaustive trawl through Marx's texts in order to ascertain what could be salvaged out of Marxism employing the tools of rational choice theory and methodological individualism (which Elster defended as the only form of explanation appropriate to the social sciences). His conclusion was that – contra Cohen – no general theory of history as the development of the productive forces could be saved. Like Roemer, he also rejected the labour theory of value and, going further, virtually all of Marx's economics.