Knowledge is a social institution, a social activity, as well as the product of that social activity. All known societies incorporate several modes of hierarchical knowledge. Three styles of knowledge co-exist in the transitional societies of the third world in general and of contemporary Africa in particular (even though in each of the latter, only one style tends to predominate). The first are initiation societies - where power is conferred on the initiated; the second are learned societies (or academies) - which handle science and technologies; and the third are industrial societies - whose enterprises apply the technologies in order to improve humankind's material and cultural condition. The initiation, learned and industrial societies were developed in a pre-modern, pre-industrial context which was monarchic, sacred, anti-democratic or endowed with a tribal democracy. A gradual opening can be seen in the passage of initiation societies (where power is the perquisite of the initiated) towards learned societies and then, later, to industrial ones. Here, the problem is knowing whether and how to bring into play a fourth style of society - cognitive society - which requires relatively advanced conditions of democracy.