Most of the chapters in the present volume discuss concrete cases in which ignorance is willfully created, strengthened, or deepened by actors seeking to further their own particular interests.1 My aim in this chapter is at first sight different. I seek to analyze the nature of ignorance and distinguish between important kinds. My approach in doing so is to focus on the role of ignorance in the search for knowledge. While ignorance can have obvious harmful aspects, the part it plays in research exposes also its constructive potential. The analysis will show that from a philosophical perspective, our ignorance ought not to be regarded as one huge, structureless absence but rather a varied realm structured by our varying abilities to articulate and pursue questions. Such an analysis will, I hope, help us to better understand the conditions under which ignorance plays out its positive or negative influence on our intellectual well-being too.