Purpose: The article discusses selected methodological issues of natural and social sciences with particular consideration of behavioural economics to highlight the significance of experimental research. Design approach: The order of the issues covered is as follows: (a) science as a product of a research community, (b) basic cognitive activities in science, (c) a short description of social sciences, (d) a discussion on the methods applied in behavioural economics. Findings: The article offers a description of research procedure, its objectives and the methods applied therein; it has been stressed that testing theories and hypotheses involves exposing them to falsification; it has been emphasised that research conducted within the framework of social sciences is more difficult than in the case of natural sciences because of the large number of independent variables and the possible interaction between the researcher and research participants. Practical implications: The content presented in the article highlights the value of scientific findings as opposed to common-sense knowledge adopted with the disregard of the principles of proper methodology. Value: The authors believe that the emergence of behavioural economics was an attempt to overcome certain deficiencies in the methodology of classical economics by means of experimental research.