Basic a assumption that scientific descriptions of phenomena are objective representations of a reality that is 'out there'. 100% accurate, derives from observation. Involves a progressive notion of science.
Cultural beliefs have no impact on science because it proceeds according to universal reason. Proper knowledge is only that which can be empirically demonstrated or analytically proven.
Positivists might not accept qualitative methods.
Positivism A philosophy of science which bases the latter on the observation of data. The observation of data should be separated from the interpretation of their meanings. Truth is to be found by following general rules of method, largely independent of the content and context of the investigation. (In Flick, Uwe. (2014). An Introduction to Qualitative Research: Glossary, p. 541). (–Paola)