Although they lived a century apart, Hayek might be considered as the liberal counterpart of Marx: not only both carried out transdisciplinary studies but they also used a dialectic approach. According to Hayek, the evolution of human societies cannot remain under control because the "spontaneous social order" is opposed to "organisations", an opposition that rests upon a conflict between two kinds of rationality set at the epistemological level (I). That can only be overcome through the fine tracking of "abstract rules of just conduct" in the legal order (II). However Hayek's pessimistic view holds ground and this is the result of the divergence, in the field of economics, between the rules necessary for market order and a conception of justice within society that is too ambitious and can even be so corrosive as to destroy it (III). To conclude, we shall ask the question what act as safeguard nowadays so as to allow liberal societies to survive, as Hayek sought to guarantee.