Measurability

We discuss measurability, intended as the fundamental problem of assessing what can be measured.We review some of the main ideas that have been historically proposed on this subject, including the positions of Helmoltz, Campbell and Stevens, the representational viewpoint and some criticism of it.Then we propose an approach that attempts to combine scientific rigour with openness to innovation and we discuss its applicability to both fundamental and derived quantities, in virtually any scientific domain.Such an approach may be particularly suited for addressing the measurement of quantities related to human perception.