 As noted earlier, philosophical interests in dispositions principally centre around the issue of how to explain them in more readily understandable terms. This issue came to the prominence in the early 20th century when philosophers aspired to construct an empiricist language in which all meaningful sentences including dispositional sentences can be analyzed in observational and extensional-logical terms. One early attempt at analyzing disposition ascriptions on the empiricist program is made by Carnap (1928, 1936–7) who considers the so-called reduction sentences as a way of introducing dispositional expressions into our language: