The Demarcation Problem Description One critical issue facing philosophers of science is how to define science, as opposed to pseudoscience. This is a serious question that should not be oversimplified, and there is much to learn about the practice of science in the attempt to construct a definition which simultaneously admits all legitimate scientific pursuits while omitting all nonscientific ones.
Positivism is the concept that what defines science is the requirement of verification.
Therefore, the hypothesis that all swans are white is scientific because it can be verified by observing swans to see if they are white. If even a single black swan is observed, however, the hypothesis will have been falsified. He therefore argued that it is falsifiability which defines a scientific hypothesis. This definition is still useful, but it is now felt that falsifiability is an essential, but insufficient, criteria for science. Many disciplines, such as some astrologers, do pose falsifiable hypotheses, but this does not rescue them from practicing pseudoscience.