Educational systems tend to remain the exclusive preserve of an intellectual elite, the product of the bourgeois class which built the system and continues to dictate its law and moral values. Such systems do not aim to exclude people on the grounds of their social background, but co-opt the best, as defined by the existing social elite. Hence the school acts as a sieve, starting in the elementary classes and operating through successive stages of filtering with an eye to selecting the future elite. And if social mechanisms inevitably favour the academic success of children from privileged social and cultural backgrounds, this is seen as a consequence and not as an aim of the system.
This conception of social advancement through education is typical of blocked societies whose sole purpose is their own perpetuation, but it also affects societies in evolution, both in developing and developed countries.