The main objection to functional type of reasoning is that it treats an effect as a cause. Thus Davis and Moore’s theory of stratification outlines the positive effects or functions of social stratification and then proceeds to argue that these effects explain its origin.
But an effect cannot explain a cause since causes must always precede effects. Therefore the effects of stratification cannot occur until a system of social stratification has already been established. It may be argued that members of society unconsciously respond to social needs and so create the institutions necessary for the maintenance of society. However, there is no evidence of the existence of such unconscious motivations.