The theory of cultural evolution proposed by economist Friedrich August von Hayek is without doubt the most harshly criticized component in his highly prolific intellectual corpus. Hayek depicted the emergence of the market order as the unintended consequence of an evolutionary process in which groups whose rules of behavior led to a comparative increase in population and wealth were favored over others. Key to Hayek’s theory was the claim that the rules of the market, on which modern civilization relies, evolved (...) at the meta-individual level and therefore surpass human reason. Hayek believed that his theory provided scientific explanation for the superiority of the market order over rational planning. In this article, I conduct a selective comparison between Hayek’s and Darwin’s theories of cultural group selection and analyze the role that demographic growth and reason play in their respective accounts. I first present Hayek’s theory of cultural group selection, its sources of inspiration, and its important place in his intellectual legacy. I then compare Hayek’s claims to Darwin’s views and highlight fundamental differences in their evaluation of the role of reason in moral evolution. Finally, I offer some comments concerning the place assigned to demographic growth in Hayek’s theory and his over-reliance on economics in explaining cultural evolution. (shrink)