 The driving force of history, in Cohen’s reconstruction of Marx, is the development of the productive forces, the most important of which is technology. But what is it that drives such development? Ultimately, in Cohen’s account, it is human rationality. Human beings have the ingenuity to apply themselves to develop means to address the scarcity they find. This on the face of it seems very reasonable. Yet there are difficulties. As Cohen himself acknowledges, societies do not always do what would be rational for an individual to do. Co-ordination problems may stand in our way, and there may be structural barriers. Furthermore, it is relatively rare for those who introduce new technologies to be motivated by the need to address scarcity. Rather, under capitalism, the profit motive is the key. Of course it might be argued that this is the social form that the material need to address scarcity takes under capitalism. But still one may raise the question whether the need to address scarcity always has the influence that it appears to have taken on in modern times. For example, a ruling class’s absolute determination to hold on to power may have led to economically stagnant societies. Alternatively, it might be thought that a society may put religion or the protection of traditional ways of life ahead of economic needs. This goes to the heart of Marx’s theory that man is an essentially productive being and that the locus of interaction with the world is industry. As Cohen himself later argued in essays such as “Reconsidering Historical Materialism” (1988), the emphasis on production may appear one-sided, and ignore other powerful elements in human nature. Such a criticism chimes with a criticism from the previous section; that the historical record may not, in fact, display the tendency to growth in the productive forces assumed by the theory.