Designers employ a range of tools in most design projects, yet there are few frameworks for understanding how and why they work. On the basis of a well-established school of thought, pragmatism, this paper contributes with a coherent conceptualisation of tools in design, which I label instruments of inquiry. This perspective underscores the crucial role that instruments play in design, and the ways in which they scaffold design creativity and exploration. In particular, it highlights that instruments not only augment our capabilities for carrying out intended actions, they also guide our perception and understanding of design problems and solutions. I present and discuss a framework consisting of five qualities of instruments of inquiry, which make them valuable in designerly inquiry: perception, conception, externalisation, knowing-through-action, and mediation.
