There is a line of thought starting with the ancient sceptics, revitalized by Montaigne, and appropriated by certain modern thinkers, including Max Weber, which points to the root-incapacity of human reason and all theory to articulate an absolute conception of reality. Whether the argument starts with the divergence and variegation of sensory awareness, whether it points to the contingency of all human experience and its interpretation, or whether, in modern form, it advocates positions with respect to the Real instead of univocal solutions, the central direction of this theme is clear: it posits an alienation of the intellect from the grounds of assurance and certitude. The latest turn given this development is its historicization through the categories of sociology, and the clearest and most forceful expression of this style of analysis is Karl Mannheim's sociology of knowledge. I propose to take it as the framework for my remarks and to restrict myself to the epistemological aspect of Mannheim's work. What I have to say does not refer to his so-called substantive sociology.