"Regarding social order, Fukuyama writes, "The systematic study of how order, and thus social capital, can emerge in spontaneous and decentralized fashion is one of the most important intellectual developments of the late twentieth century." He correctly attributes the modern origins of this argument to F.A. Hayek, whose pioneering contributions to cognitive science, the study of cultural evolution, and the dynamics of social change put him in the forefront of the most creative scholars of the 20th century. But Hayek's views about the "spontaneity" of social order remain controversial. In their extreme form, they imply that all deliberate efforts to manipulate social order — social engineering — are doomed to failure because the complex nature of our cultural heritage makes a complete understanding of the human condition impossible. Hayek was certainly correct that we have, at best, a very imperfect understanding of the human landscape, but "spontaneous" it is not. What distinguishes human evolution from the Darwinian model is the intentionality of the players. The mechanism of variation in evolutionary theory (mutation) is not informed by beliefs about eventual consequences. In contrast, human evolution is guided by the perceptions of the players; their choices (decisions) are made in the light of the theories the actors have, which provide expectations about outcomes."