 The linguistic turn framed the examination of the controversial role of experience. In that respect the discussions of protocol sentences, the so-called protocol sentence debate, addressed their linguistic characteristics and their epistemological status (Uebel 1992). It was another dimension of their examination of both the source of human knowledge and the rejection of metaphysics as nonsense—often dangerous nonsense (Carnap, Hahn and Neurath 1929/1973, and Stadler 2007).