Critical Realism (CR) is a philosophy of science that is based around a number of ontological principles. Epistemologically, CR provides principles that can be applied by researchers developing theoretical explanations about phenomena in the world. It therefore functions at a level similar to that occupied by such philosophies as Positivism and Interpretivism. Because CR principles are usually used to underpin the development of theoretical explanations it is more accurately considered a "metatheory", rather than a "theory".