What exactly do we mean when we refer to disability as a social construction? How viable are the justifications for this? These questions are explored in this paper. To this end, various theories that are influential in German-language disability studies are examined and criticised. These include Oliver's social model, furthermore the "Thomas theorem", Berger and Luckmann's sociology of knowledge, Foucault's discourse theory and Waldschmidt's theory. Subsequently, social constructivist approaches of Watzlawick and Gergen and Gergen are discussed. It is shown that (...) a relativistic understanding of social construction can be used to deny facticity and thus undermines the foundations of scientific knowledge. This danger must be taken seriously when defending the scientificity of disability studies. (shrink)