Social closure refers to the phenomenon by which groups maintain their resources by the exclusion of others from their group based on varied criteria. Closure is ubiquitous, being found in groups all over the world at all sizes and classes. Some examples of social closure include, “Access to private schools follows explicit rules and depends on financial capacities; access to university depends on a certificate or diploma, eventually from certain schools only; membership in a highly prestigious club depends on economic and social capital and the respective social networks; and finally, in the case of migration, people will have to be eligible for citizenship and pass the thorny path of naturalization.” Mechanisms of social closure Blacklisting In employment for example, blacklisting refers to denying people employment for either political reasons (due to actual or suspected political affiliation), due to a history of trade union activity, or due to a history of whistleblowing, for example on safety or corruption issues. Blacklisting may be done by states (denying employment in state entities) as well as by private companies. Theoretical framework Frank Parkin's closure theory Frank Parkin most fully laid out his social closure theory in Marxism and class theory: A bourgeois critique. In quite sharp tone, Parkin argued that Marxist theories of social class were marked by fundamental deficiencies, particularly associated with the ambiguous status of their central explanatory concept, mode of production. He attacks the Marxists' overemphasis on deep levels of structure, at the expense of social actors, and suggests a radical recasting of the theory of class and stratification. He proposes to do this by centering theory around the concept of social closure. Parkin follows Weber in understanding closure as:Parkin goes on to elaborate this concept, by identifying two main types, exclusionary and usurpationary closure. 'The distinguishing feature of exclusionary closure is the attempt by one group to secure for itself a privileged position at the expense of some other group through processes of subordination'. He refers to this metaphorically as the use of power downwards. Usurpationary closure, however, is the use of power upwards, by the groups of subordinates created by the exclusionary closure, aimed at winning a greater share of resources, threatening 'to bite into the privileges of legally defined superiors'. Arguably, the most novel aspect of Parkin's contribution was that he wanted to define classes in terms of their closure strategies, as opposed to defining class with