" The failure of Popper's demarcation criterion throws up an important question. Is it actually possible to find some common feature shared by all the things we call 'science...'? It may be that they share some fixed set of features that define what it is to be science, but it may not.... If so, a simple criterion for demarcating science from pseudo-science is unlikely to be found. "

― Samir Okasha , Philosophy of Science: A Very Short Introduction