Economists have sometimes posited that there is such a being as the 'Economic Man', the implication being that we are all economically rational creatures. Modern economic concepts are largely foreign to non-industrialized societies whose rudimentary economies have a peculiar rationality of their own. For instance, the modern emphasis on efficiency of production per unit output is difficult to apply to a kin-based economy. The particular feature which vitiates the economic arrangements in both simple and complex pre-industrial societies, and which more than anything else demonstrates a difference of mind-set between them and modern post-industrial society is that of religious ideology. Fundamentalist Islam is nothing if not pragmatic about anything that serves its interests as recent events in Egypt and Algeria have borne out. But it is not alone. Ideology can be flexible when the situation demands it. Similar kinds of opportunism are also the mark of many left-wing Marxist-inspired movements.