According to Weber, political legitimacy is the support that power can mobilize for its reign among the population. Roughly speaking, one might say that an ideology attempts to convince suppressed people that their poverty is sacred, rational, just or necessary. Power legitimizes itself perhaps primarily by showing itself to be "necessary", by implying, rather than stating, that "there are no alternatives". See hegemony. More generally, "legitimacy" is used about any confirmation of phenomenon's conditions of being. When fieldworkers "legitimize" themselves in the field, they make it seem probable to their informants that the anthropologist has a valid reason for being with them. Østerberg (1963) says that one legitimizes one's own acts by describing the motive that supposedly preceded them, although in fact there may not have been a clear motive.

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