Search engines must be understood from the perspective of their relation to knowledge and understanding. The term does not merely refer to Google or Yahoo!, but to the 'extended mind' that challenges our very understanding of knowledge and is made possible by the convergence of different disciplines across computer science, such as semantic web, AI, or ubicomp. The ubiquitous availability of information seems to ease the access and accumulation of knowledge. On the other hand, knowledge conditioning access itself is becoming universal and absolute: what matters now is probably not the problem of access, but rather the conception of knowledge and understanding through the extended mind. First, Kant's opposition between rational knowledge and historical knowledge, and the positioning of algorithmatic knowledge in such an opposition must be re-assessed. Second, we must re-access Durkheim's "social categories" that are now becoming synchronized in favor of a unified, transcendental knowledge in its becoming, especially today when web ontology becomes the key to information retrieval. These two reassessments attempt to reinterpret our understanding of knowledge, with respect to cognition and sociality in the critique of search.