Much anthropological literature regards ‘knowledge’ as an unproblematic accumulation of what people claim to know about the world, their social relations, cosmology, and practices. The flip‐side to knowledge, namely ignorance, however, is rarely considered. To speak of knowledge deprived of its relation to ignorance is like speaking of velocity devoid of a notion of distance. The paper explores what an anthropological conception of ignorance might look like. It reflects on the problem of ignorance in anthropological theories of knowledge, and illustrates the issues with a case study of the knowledge practices of Senegalese craftspeople and French colonial officers and administrators in West Africa.